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April, 1943 NEWNES PRACTICAL MECHANICS 217

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ENGINEERINGWORKSHOP PRACTICE

Recent developments in engineering workshop practicehave been so rapid that it has been found necessary toproduce a new and revised edition. This new editiondeals with the underlying principles, craftsmanship,machines, tools, measuring processes and machiningmethods of to -day, and it, will prove indispensable tothe engineer, draughtsman, mechanic, apprentice andengineering student. Its scope extends from simplehand tools and machines to the latest elaborate machinesand methods employed for mass -production purposes.

SOME OF THE SUBJECTSFiles, Chisels, Scrapers, Shears, Punches, Burnishers, Hand

Screw -cutting Tools, Spanners, Vices, Various Measuringmethods. Verniers, Micrometers, Gauges, Optical Devices,Fluted and Twist Drills, Grinding Angles, Drilling Data,Small and Large Drilling Machines, Electric Drills, PracticalLathework 40 all its branches. Machining of Metals andSynthetic Materials. Tungsten -carbide and Diamond Tools.Lapping, Honing, Cleaning, Polishing and Rust -protection

- of various metals. Grinding Operations and Machines,Milling Operations, Cutters and Machine?;. Planing, Shaping,Slotting and Broaching Operations. Special Machines forProduction Purposes. Plate and Bar Machines. Gears andGear Cutting Methods. Templates, Jigs and- Fixtures,Overhauling and Adjusting Machines, Millwright Work.Welding, Brazing and Soldering Metals. Forging Work.Sheet Metal Work. Foundry Work. Patternmaking Practice.Press Work. Engineering Steel and other Metals ; theirProperties, Testing, Hardening, Tempering and Annealing,Engineers' Drawings. Workshop Calculations, , Data, Hintsand Recipes. British and Foreign Screw -thread Tables.

THE ILLUSTRATIONSThe book is lavishly illustrated so that the explanations

are rendered 'very clear with examples taken up from actualworks practice in many instances. There are 24 -full-pageplates and 1194 line and photographic illustrations in the text.

ENGINEERING POCKET BOOKIn order to make the work even more comprehensive we

have brought out a pocket book, which is supplied free to allpurchasers. It contains many useful tables of Screw Threads,Tapers, Angles, Drill Speeds and Sizes, etc.

A FREE BOOKLETTo The Caxton Publishing Co., Ltd.,

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Please send me, tree of charge, Illustrated Booklet describing"Engineering Workshop Practice."

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218 NEWNES PRACTICAL MECHANICS April, 1943

AMB TIOUS ENGINEERSHAVE YOU HAD YOUR COPY OF

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PRACTICALMECHANICS

Owing to the paper shortage " The Cyclist," "Practical Motorist," and "Home Movies " oretemporarily incorporated.

Editor : F. J. CAMM

VOL. X. APRIL, 1943 No. 115

BY THE EDITOR

Civil Aviation After the WarTHE Government has decided that plans

may be prepared for post-war civilaviation and designs for suitable types

of aircraft put in hand at once. The Govern-ment intends to 'back this project, and hasstated that it cannot be left to private enter-prise. As far as international airways andcommercial aviation are concerned it makesthe broad hint that it is prepared'to co-operatewith other nations to mutual benefit asdistinct from cut-throat competition, but thatif other nations prefer competition GreatBritain will be equal to it, with the bestmachines in the world. The desire is to linkup the Empire by air, in the first place, butobviously air communications with othernations will fall into a general scheme.

The development of air travel must not takeplace too suddenly after the war, for therailways and shipping companies will needtime to accommodate themselves to thisnewest rival. We do not need to solve oneproblem, that of rapid international travel, atthe expense of another. Here is one of thebeneficial services ,of war. It developsparticular inventions and discoveries to apoint which it would take. 5o years of privateenterprise to attain, In the debate in theHouse of Lords Lord Londonderry said thatthe Government desired this branch of aviationto be separated from the Air Ministry, and thata monopoly should -not be given to anyaviation company. At the same time thesecompanies should be told the Governmentpolicy so that they could make plans andprepare designs for aircraft production. Thefuture of air transport depends primarily onthe arrangements made about militaryaviation after the war. Fmedom of theair must be established by rules and regula-tions internationally agreed and administeredby the United Nations with an internationalpolice force. It is known that America isthinking and planning for post-war commercialaviation, and it is essential that this countryshould notbe behind the times. Of course, inAmerica there are efficient privately runair -lines as there were in this country beforethe war. After the"war transport 'planes willbe needed in tens of thousands to fly food toareas which cannot be reached by sea, and totransport, war supplies in the expected waragainst the Japanese.

Careers in Aviation

NOW that the Government has announcedits plans, interesting opportunities are

opened up for careers in aviation-a point wehave so often stressed in this journal: But whilstthe Government is to control the developmentwe must not be unmindful of the fact that the

Government did not create the aircraftindustry in this country ; it was built upby private experimenters, backed by thosewith long vision who saw no immediateprospects for the return of their money, andwho thus can claim some credit for remainingin the industry at .a time when they receivedno encouragement whatever from the Govern-ment.

The DebtVERY few aviation companies ran at a profit

prior to the war. Few; if any of them,are able to make much out of the war owingto the excess profits duty. This country owesa great debt to the small and strugglingindustry which remained alive and was a goingconcern when this war started. Withoutaircraft we should have lost the war, foraircraft staved off the German attacks andgave us breathing space to rearm: We haveample evidence now of the important part itplays in warfare. It can equally play animportant part in peace, when commercegets' going again. Sea travel is slow, thoughreliable, and it is not suggested that aircraftshould entirely replace ships. In the firstplace the pay load of an aeroplane must alwaysbe considerably less than a ship of comparablepower. An aircraft to carry 50o peoplemust necessarily be large dud highly powered.It will be some years, no doubt, before we candevelop the large transcontinental air liners.The War Cabinet has taken the decision thatthe design of a limited number of types ofaircraft shall proceed with the assistanceof the Government as and when it can bearranged without. interfering with aircraftrequired for the war.

Much will depend on how this present warends, and the sort of agreement reachedbetween the Allied Nations.

A Young Man's Job ?FLYING is essentially a young man's job,

and if commercial aviation is to be'established on a large scale, there must bea constant influx of new pilots and otherpersonnel who actually take the machine intothe air, or, alternatively, the flying life of thepersonnel' must be raised. The presentstandard of physical and mental fitnessrequired for pilots is severe, because of thehigh speed. But then a commercial 'planeof any weight will not ccnzeivably have a speedmuch lower than a fighter, so it may not befound possible to lower the medical Standard.This will create employment problems.If a pilot's flying life is found . to be, say, atmost, five years, what is to happen to him

after that time ? Is he to be demoted to ,aground staff job ? Obviously the design sidecould not absorb so many who would bereleased froth flying duties. However, a newindustry has been born, and only practicalexperience when it gets going will solve thedifficulties. In any ease, the aircraft factorieshave by the Government statement of policyreceived an assurance that they will not becast aside as they were after the last war andleft to peddle around in foreign markets tokeep their factories running. Aircraft workers,too, will be reassured that they are not to bethrown on the unemployment market whenorders for military aircraft do not flow sofreely as at present.

There can be no doubt that when this waris over we shftll continue to buildaircraft, for we shall have the task with theUnited Nations of policing Europe, and ensur-ing that the world does not again suffer fromHitlers, Mussolinis, and all the other pocketNapoledns and imitation jack -booted Cxsars.

QueriesWE continue to receive a very large number

of qtieries of a highly involved nature,occupying far more time than. the TechnicalStaff is able to spare during the war when thereare so many other calls, official and otherwise,upon their time. We ask our readers, there-fore, to limit.their queries and to refrain fromasking non -essential questions such as those" to settle an argument," mathematicalpuzzles, and the more idle questions such aswho first invented gunpowder. -

We do not undertake to answer queriesrelating to legal matters, and in certaincircumstances we may not answer queStionsrelating to military aircraft owing. to thecensorship. Owing to staff shortage we cannotguarantee to reply by return of post ashitherto.

All of this means that we are asking for theco-operation of our readers in reducing thenumber of queries submitted and to keepthose which they do submit as brief as possible.

IndexesINDEXES for Volume 9 are now available ;

they cost 9d. each, or told. by post fromThe Publisher, George Newnes, Ltd., TowerHouse, Southampton Street, London, W.C.z.Every reader should obtain a copy of theindex if ,he keeps back copies, and we suggestthat he should. If readers before submittingqueries consulted the indexes they wouldfind most probably that their particularproblem has been dealt with in pastissues.



Aero-en

THE function of the igtfition system is toprovide a series of sparks with whichthe combustible mixture of air and

petrol vapour inside the cylinders is fired.With present-day engines running at 3,000r.p.m. and having up to 24 cylinders with 48sparking plugs, it will be seen that very greatcare is necessary in the design and con-struction of the various detail parts.

There are two main methods of producingsparks, i.e., coil ignition andmagneto ignition. For aircraftpurposes the coil system is notgenerally used, and systems in-volving the use of magnetos are.the general rule. The reasonsfor this choice are as follows.Firstly, the magneto can supplysparks at a greater rate. Secondly,the fire risk in the event of acrash is higher where a coilignition system is fitted due tothe necessity of installing bat-teries and the attendant wiring.Thirdly, the effect upon the radioreception when the main air-craft batteries are used to supplycurrent for the coil is verymarked and renders good reception im-possible due to the interference. On theother hand, however, there are severaladvantages on the side of coil ignition. Nohand -starter is required as the sparks producedat low engine speeds are as good as thoseproduced for normal revolutions due to thefact that the current is supplied from a battery.Magnetos are not efficient at low revolutions,

the ,TAnition SystemsTheir Function and Development

By T. E. G. BOWDEN, M.I.E.T.

each other, usually by means of shellac varnish.Round this core are wrapped the primarywinding, consisting of a number of turns of acomparatively thick copper wire, and thesecondary winding. This outer layer is builtup of very much finer gauge wire than theprimary winding and the number of turns isanything up to 4o times as great. The twowindings are insulated from each other. Atposition (a) in Fig. 2 the magnetic flux through

r-EARTN/N6 SW/TCl/

" r r.- I SAFETY OAP

EARTH?

0/STR/51/TORCONDENSER. /RON CORE

CONTACT BREAKER RR/NARY 11/ND/NtS

Fig. L-Diagram of an aircraft ignition system.

the armature is a maximum, and the rate ofchange of flux is obviously zero. Whenposition (c) is gained, the flux is a minimum,but the rate of change is maximum and atthis point the generated current is also amaximum. This current is induced in theprimary winding due to the fact that when aconductor moves in a magnetic field in such amanner that the lines of force are cut, a current

HORSE SHOE MAGNET

L/NESDITORCE--,,x.

c

N SFLUX MAX//11/11RATE OTC/ANS/W/4f:

Fig. 2.-Rotating

and require an additional hand -operatedbooster magneto which turns at a far greaterspeed than the engine, thus supplying asufficiently strong spark. Coil systems arecheaper to produce and easier to manufacturedue to the fact that there is no complicatedmagneto.

Magneto Ignition SystemsA typical ignition system is illustrated in

Fig: r, on which are indicated the relativepositions of, the main items of equipment.These include :

(r) Magneto.(2) Condenser.(3) Contact breaker.(4) Earthing switch.(5) Distributor.(6) Sparking plugs.

A description of these details is of interest.Several types of magneto are available at the

present time, each with its own advantagesand disadvantages. Firstly, there is the rotating

.armature type, illustrated in Fig. 2, whichoperates,as 'follows. The rotating portionconsists of an iron core constructed from aseries of H -sections which are insulated from

FLUX frI/M/11/frlRATEOFCHANGEMAX:

armature magneto.

is induced in the conductor or wire providedthat the circuit is closed.

The contact breaker, a description of whichwill be given later, is adjusted so that theprimary current is broken when position (c)is reached. By this sudden collapse andreversal of the magnetic field a high voltageis induced in the secondary winding due toclectro-magnetic induction. The collapsingmagnetic lines of force cut both the windingsand generate a flow of electric current. .Thiscurrent is passed to the sparking plugs and

aFig; 3.-Th'agratils illustrating the operation, of a polar inductor magneto.

SRAR/17/Y6 fr1/63

thus the combustible mixture in the cylindersis fired.

The main disadvantage of the rotatingarmature type is the fact that only two sparksperjevolution are obtained and a high speedrotation is required when the number ofcylinders is excessive, e.g., in the case of a14 -cylinder engine the magneto must turn at

x engine revolutions. One spark is2 X 2

required for every two crankshaftrevolutions per cylinder, i.e.,taking an engine turning at 3,000r.p.m. the magneto must revolve

14231'

2000at-10,5oo r.p.m.

. XTo increase the number of

sparks per revolution, the in-ductor type -of magneto has beendeveloped and this is illustratedin Fig. 3. In this design thecoils remain fixed and only theinductors revolve. At position(a) the core flux is maximum,in position (b) zero, and inposition (c) it is reversed and isagain a maximum. Thus it willbe seen that four sparks per

revolutiori may be obtained and consequentlythe speed of rotation may be halved whencomparing with the rotating armature type.By varying the arrangement of the magnetoit is possible to obtain 12 sparks per revolutionand by using this design a very light systemmay be evolved, at the same time reducingthe amount of space required.Rotating Magnet Type'

A modern development in magnetos is therotating -magnet type. The permanent magnetrotates and the pole pieces are stationary.The electrical system in this method isextremely efficient.

At one time safety spark gaps wereincorporated in all magnetos to preventdamage to the windings should the voltageexceed the safety limit. If there is abreakdown in the electrical distributingcircuit the voltage may reach as high afigure as 15,000 volts, and when this occursthe current is allowed to short-circuit toearth. At the present time spark gaps arenot being fitted to several types of magneto,due to the fact that many aircraft are operatingat altitudes above 25,000ft. Owing to thereduced density at these heights the gapbreaks down at a much lower voltage thandesigned for, e.g.,the current at 25,000ft.may be short-crcuited at zo,000 voltsinstead of z5,000. The disadvantages incurredby this premature earthing are obvious, asthe engines will misfire and finally ceasefunctioning. Where a spark gap is fitted itusually takes the form of two metal points,

SECONDARY W/ND/N6PR/MARY W/ND/N6



one of which is secured to the magnetoframe, i.e., it is earthed, and the other to theelectrical connection between the secondarycoil and the distributor. As an alternative totwo fixed points, some magnetos have arotating safety spark gap. This retardsionisation owing to the fact that the airbetween the two points is constantly beingchanged.

Ionisation occurs when an electric currentjumps the gap and the air is split up into ozoneand other chemical components. When thisoccurs, the electrically charged particlesreduce the normal resistance of the gap andcurrents lower than designed for will beshort-circuited. Also, should there be anydampness, nitric acid is formed and corrosionis probable. By constantly changing the air,this danger is reduced.

Contact BreakerThe next item of equipment is the contact

breaker, a typical design being illustrated inFig. 4. The function of this particular item,

CONTACTS

this means the primary circuit is interruptedearlier, consequently advancing the sparks.

As modern aern-engines turn over at3,000 r.p.m. and require 40,000 sparks perminute, it will be seen that very carefuldesign and construction is needed in the caseof the contact breaker. One trouble oftenexperienced is the transferring of metal fromone contact to the other, causing unevensurfaces and consequently inefficient operation.

Condenser DetailsA condenser is always incorporated in the

magneto and the construction of a typical oneis illustrated in Fig. 5. Its main function isto reduce the possibility of arcing betweenthe two contact points when they are open.It consists of several tinfoil plates separatedby layers of non -conducting material calledthe dielectric. One set of sheets is connectedto the positive and the other to the negative.The condenser operates as follows. As theprimary current is built up the condenser ischarged and absorbs current, as the tendency

TENO/N670KEEP CONTACTS

.1111MICIOSEDFIBRE 810CHOPERAT/NG CAM.

Fig. 4.-Contact breaker.

as explained in a previous paragraph, is tomake and break the primary circuit so that ahigh voltage is induced in the secondarywinding. The operating cam is usuallyincorporated as part of the magneto shaftand moves a hinged lever, which in turncauses the two contacts to part, thus breakingthe circuit. These contacts are arranged 'toopen at definite times so that the maximumcurrent may be obtained, i.e., when the rateof charge of flux is maximum. The materialsused for the contact points are either tungstenor platinum -iridium, both tough metals whichcan stand up to the continuous making andbreaking. From the shape of the camillustrated in Fig. 4 it will be seen that thecurrent will be interrupted four times perrevolution, i.e., the magneto is a polar inductortype. The gap between the two contactsmust be set accurately and is usually between.ot tin. and .ot4in.

Double -contact BreakerA development of the simple contact

breaker is the double -contact breaker, whichallows the sparks to be advanced or retardedeither automatically by being connected tothe throttle lever, ,or independently by thepilot of the aircraft. This type of contactbreaker incorporates two sets of levers andtwo sets of contacts operated by the same cam.A switch is installed which allows the currentto flow to either the retarded or the advancedbreaker. This switch is usually operated bymeans of a cam which in turn is moved by alever connected to the throttle linkage. Athigh cruising engine speeds the spark requiresto be advanced, and when the speed is reducedthe spark is automatically retarded. Atmaximum engine revolutions the spark is alsoretarded to reduce the tendency to pre-ignitiondue to the high boost pressures.

The above design of contact breaker isusually fitted in combination with anotherautomatic retarding and advancing mechanism.This device operates centrifugally, the drivingshaft from the engine being separated from themagneto shaft by means of several springs andweights. As the engine speed increases theweights are forced outwards due to centrifugalforce, and the position of the magneto shaftrelative to the driving shaft is altered. By

TIMM& SHEETS

Fig. 5.-Condenser.

is for the current to flow into the condenser,following the path of least resistance. Whenthe contacts open the current induced in theprimary winding also follows the easiestroute and passes to the condenser instead ofjumping across the air gap between. thecontacts. Another advantage is that the rateof collapse of the primary magnetic field isquickened, thus increasing the voltage in thesecondary winding.

In order that the engine may be stopped,an earthing switch is installed, positioned asshown in Fig. I. When closed the switchearths the primary current before it reachesthe contact breaker, thus preventing anyinduced current in the secondary winding.

DistributorThe high tension current is ,4pRox..300

conveyed from the magneto tothe distributor, which,, as itsname implies, distributes thecurrent to the sparking plugswhen and where required. Abrass ring is usually fitted to themagneto shaft and a carbon brushcarries the current to the dis-tributor, a typical design of whichis illustrated in Fig. 6. A series ofmetal segments, all insulated from eachother, are fitted into a case and connectedwith electric leads to the plugs, i.e., if thereare 12 sparking plugs, there are 12 segments.The high tension current is passed to eachplug in turn by means of a rotating armdriven by gears from the magneto drive.These segments are usually manufacturedfrom nickel or gun-metal and the case froma non -conducting material.

The rotor brush does not actually come intocontact with the segments as a rule, but isgiven a clearance of approximately .o15 in.This gap is incorporated for the followingreasons. Firstly, there is less wear as norubbing contact occurs. Secondly, the maxi-mum current is passed to the sparking plugs,due to the fact that the air gap insulates thesecondary winding until the maximumcurrent is available. Another factor is thatas, the segments are not flush with the casingthe jumping of the current from one segmentto another which is likely to occur when

STARTERBUSH

actual contact is made due to particles ofcarbon becoming detached, is reduced.

A trailing brush is often attached to themain distributing brush being set at anangle of approximately 3o deg. When a handstarter magneto is used the current producedis passed to the trailing brush. The reason forthis is to ensure that the spark occurs late,so that pistons will be over top dead centrebefore the mixture is fired. This preventsany possibility of backfiring and consequentdamage to the engine.

Sparking PlugsAfter passing through the distiibutor the

current flows to the sparking plugs, the designof which has reached a high standard ofefficiency Their function is to provide aspark at regular intervals, and at the correcttime. H.T. current is passed down a centralelectrode constructed of steel and surroundedby an insulating material. At the lower endof the electrode is the firing point, at whichthe current jumps across a gap, thus givinga spark, and passes to the outer casing, i.e.,to earth. Sparking plugs have to stand up toextremely hard conditions, due' to, the hightemperatures in which they work and theirliability to be oiled up. The deposition ofcarbon must be resisted and overheatingavoided, if pre-ignition is not to take place.Most aircraft engines have two plugs percylinder, each supplied with current from adifferent ignition system.

Various developments in plug design havetaken place in recent years, but still moreare required before they can be said to beabsolutely reliable.

From the above .description of the variousdetails and the path of the current, a goo.didea is gained of the arduous conditionsunder which the ignition system functions.The main difficulty that requires overcomingis the reduction in efficiency which occurswhen flying at high altitudes. An importantfactor when dealihig with this problem is thatsparking plugs, when set at the correct gap,allow a greater altitude to be gained thanwhen the gap has widened due to erosion.Another serious disadvantage is the leakageof the current from the brush to incorrectsegments in the distributor due to ionisation.

Fig. 6.-Diagram

SEGMENTS CONNECTEDTO SPARKING PLUGS

/MN BRUSH

ROTATING PORT/ON

of the distributor.

Future DevelopmentCoil ignition will undoubtedly be utilised

when further development has taken place,and interference with radio reception avoided.Sparking plugs using mica as the insulationare being superseded by plugs using syntheticmaterials. Mica tends to become pinholedand leaded fuels cause deposits which lead topre-ignition troubles. Sintered aluminiumoxide has been found to possess very goodinsulating properties..

All the ignition system should be screenedto prevent bad radici effects, and most mag-netos and sparking plugs are enclosed in metalcasings for this purpose. The electrical leadsare also metal covered (see inset on cover).

Summing up the position as to the futuretype of ignition system, it will be seen thatfirstly, magnetos using rotating magnets willbecome the standard ; secondly, that coilignition will be developed ; and thirdly, thatsparking plugs, with further research, willneed less attention than at present.



THE planning of engineer pre -built housesrepresents the fundamental basis andthe starting point in the design and

detailing of the various units to meet domestic,structural and aesthetic requirements. Thereis a tendency for enthusiasm in new methodsof construction to override common-senseprinciples and requirements. This tendencyreally must not exist if a full measure of successis to be attained. The chief fundamentarandessential requirements in any house are : (1)good planning to provide the requirednumber of sufficiently large and well locatedrooms and other compartments to ensurecomfort to the inhabitants ; (2) the dispositionof windows, doors and fireplaces in 'the roomsso as. to allow furniture, beds, furnishings,curtains and all other domestic articles to beplaced, and used, so as to obtain the maximumcomfort and comply with hygienic essentials ;(3) the provision of well designed andconstructed equipment to case the housewife'sduties, and to contain thosemany articles and thingswhich are so necessary andvalued by all home -lovers ;(4) a house which iseasily kept clean ; (5) and,although not closely con-nected with actual planning,may at this stage be men-tioned the important matterof thermal and acousticalinsulation of floors, walls,partitions and roofs. If thesefive essentials are borne inmind by the structuralexperts in pre -building, thena good moiety of the battleof engineers versus jerrybuilders will have been won.

One of the cries of oppo-nents to pre -building is thatthe widths, depths andheights of houses, and thesizes of rooms, must begoverned by the size of theunits, or, in other words,there will not be such dimen-sional fluidity as to avoid afew simple mathematical cal-culations to get the bestnumber of houses in a givenfrontage or acreage. Mycomments to this cry, pre -ambled with " rot ! ", are :strip, undersize and oversizefiller units will permit dimen-sional fluidity to meet themost fastidious and practicalrequirements. Does themodern householder and hisfamily care whether a houseis a few inches under or overin frontage, depth from frontto rear, height or size ofrooms if all comfort condi-tions are provided ? Certainlynot. Are the stereotypeddesigns and dimensions ofthe pre-war houses a criterionof dimensional fluidity ? No.Of paramount importance

EnAineer-built Houses ofd.1.r ritt; the Future -3

Planning, Building By-laws, Advantages of Pre -built Houses

By R. V. BOUGHTON, A.I.Struct.E.

to the householder, the housewife andtheir family are much more vital matters;those which allow choice, freedom and ease infurnishing, colour schemes, warmth and theeconomical enjoyment of home- as apart from -business life.

Figs. 7, 8 and 9 provide only a very smallproportion of the great range of planning tosuit post-war requirements. The key plansat the foot of this page are only a small varietyof general layouts. Architects will undoubtedlyprovide many other types of layouts, and wellproportioned elevations to assist the engineersin the manufacture and supply of pre -builtunits and sets to suit the New Order.

Fig. 7 may be taken as the basis forexplaining many principles of good planning.It typifies one of the most popular pre-warlayouts for the ordinary six -roomed semi-detached house. The main rooms of thepair of houses are adjoining the party wall,this arrangement giving the minimum amount

f/R5T STOREY

GROUND -STOREY:"

Fig. 7.-A 'popular type ofplanning for a 6 -roomed house.

F/55T _5TOR'e)

GROUP1D STOREYFig. 8.-A 6 -roomed house,with unique planning havingseveral advantages over that

of Fig. 7.

of external wall to each room, therebyproviding thermal advantages, the staircaseand main door to each house are not closetogether, thereby giving privacy, thefireplaces and chimney stacks are well groupedtogether, which is an advantage in keepingthe flues warm and with a good up -currentand the disadvantage of neighbours' noisesbeing a nuisance may be avoided by properacoustical insulation. An alternative to thisplanning is to place the stairwell and kitchenof each house next to the party wall, and themain rooms adjoining the flank walls ; Fig. 8,although of different planning, depicts thegeneral idea : The ground storey, as inFig. 7, comprises a lounge and dining roomof reasonable size, each having built-incabinet fittings, ample window space, andheating stacks for -coal, electricity or gas, or acombination of coal and one of the otherheating mediums ; a kitchen of suitablesize, well equipped ; a hall and stairwell of

fl25T STOREY.

GROW YD _5701?frFig. 9.-Planning of a garage type

6 -roomed house.

Fittings and equipment: A.-Cabinet ; part of the specially -designed structural and utility equipment. B.-Hallcabinet. C.-Larder. D.-Sink and draining hoard. E.-Boiler. F.-Cooker. G.-Bedroom wardrobe.H.-Linen cupboard. .7.-Bath. K.-Lavatory basin. L.-Bulkhead. 'M.-Built-in dressing -table. N.-Beds.

O. Fireplaces. P.-Electric or gas fire, in smallest bedroom. Q.-Shower. R.-Refrigerator.


April, 1943

good width- and length is provided witha tradesmen's and garden door,- plenty ofspace for a baby -carriage, and a clothes cabinet.The first storey contains two large bedrooms,suitable for beds as shown, each room havingdouble built-in wardrobe cabinets, alsodressing -table cabinet by window, and firestacks situated in sensible positions, assuggested in our Women's Column, at the

Fig. to.-.1 typical pre-warground plan of a 6 -roomed house.

end of this article. There is a small bedroomwith a single wardrobe, The bathroom andW.C. are in separate compartments. Theupper hall is spacious and well lit, containsthe stairs leading to ground storey and alsoroof garden, also a linen cupboard whichhouses the hot water tank with cold watercistern over in roof stairwell.

The plans, as Fig. 8, are departures fromthe common pre-war type of planning, andhave a few advantages when compared withFig. 7. The hall and kitchen adjoin the partywall, and the absence of any stairs in the formerallows for spaciousness. The stairwellsituated between the front and back mainrooms in each storey permits the ,width of

NEWNES PRACTICAL MECHANICS

the use of standardised units, and anyparticular variation or requirement may bemet with " filler units." The block planlayout will indicate to the designer manypossibilities in planning.

The effect of thin walls plays a ratherimportant role in the allocation of frontageto houses, especially if land is expensive.As an example, if a pair of semi-detachedhouses require a frontage for actual building(not including side passages, etc.), of. 4oft.,the two flank and one party wall, if one brickthick brickwork, takes eft. Sin. of the 4oft.With scientifically designed pre -built workthe flank walls will not exceed 4in. thick, theparty wall either the same, or 6in. if anyspecial sound insulating principles are adopted,and therefore the three walls will total Ift.or sit. 2in. This reduces the frontage ofeach house by about 6in., and, with land at,say, £5 per foot, this is certainly a considera-tion. Engineer -built houses will certainly nothave fireplace breasts, mantels and hearths,taking up such a valuable amount of space of

223

living and bedrooms, and in this respect it isright to conclude that any reduction of floorspace caused by using lesser lumps of brick-work, etc., may cause a little reduction in thewidth of rooms and thereby in the frontageas well.

By-lawsBuilding by-laws have received much

attention by the authorities in the interim ofthe last and the present wars, and particularlyduring the few years preceding 1939. I feelsure it is the intention of the authorities tomodernise and augment existing by -lays toallow rull scope for the great advancement inbuilding. It is almost certain that waiversfrom existing rules will be readily and freelygranted in the case of all applications whichare substantiated by evidence, which I submitcan be incontestable, as to the adequacy instrength and fire -resisting qualities of engineerdesigned and built houses, which will beexplained in detail in this series of articles.

(To be continued.)

The Woman in the Home(This Month It, is by Mrs. R._ V. BOUGHTON)

MUST confess a little timidity when Iwas asked to approach the Editor of this

journal for permission to place women'sideas on how their homes should be designed,and not leave all matters to " mere man."You see, I had never written an article before,and I feel that there are many women likemyself who know only too well what is wantedin a home, but cannot express themselvesjournalistically. The success which I haveachieved with the Editor J am sure otherwomen can do as well, and a particular appealis made by me to all men readers to discusswith their womenfolk some of the homematters which affect the designing andequipment of the home. Don't say youcannot draw or put into words your idea. Icannot draw, so just do what I did-make a

THE ROOMFURMISHED 70.501T Mkt PL/144MO.ONL-SiDED AMMOD oPCARPET TO RED Afroor ROOMCARPST

FIREPLACE.Ito DEAR RED,WAROROM,DRESS/MC TA01.E.

and I said it could be better, and that somethings were the silly results of men's andnot women's brains. Of course, it was allsaid very nicely, but I knew I was gettingmy way. Well, as there was no basement tothe house, I suggested it would be as wellto have a look at the bedrooms upstairs.

' Fig. 11 is a plan of the " best bedroom,into which we wandered, with the builders'salesman, " tub -thumping " his usual dopeabout the chromium plated fittings and aboutthe proof that the house must be good becausethe building society would advance 95 percent. of its value (questionable). It wasmutually agreed that the great lump ofbrickwork sticking out into the room to takea small fire, and, so I was told, a flue fromthe room underneath, together with the

THE fiREFur_eTo Su/Ts THEFURNISHINGBED.CARPET EALDACEoOr ROOM ADO DEO

ELECTRic OR GASPAM Dr GOOD 012.5incovCART w ee commknowSPACE In nirwr OPP,

--WARDROBE

DRESS/DC TABLE

Figs. It, 12 and 13.-A typical bedroom plan, and diagrams showing how a .better furnishing arrangement is obtained.

hall to be less than if it contained the stairs,the space under stairs is utilised for cabinetsas shown, and the lower and ,upper hallsare well lighted. The planning ox the firststorey does not permit quite such large mainbedrooms as indicated in Fig. 7, unless thedepth of house is incitased ; but they are ofa size preferred by many people., The smallbedroom is of very, comfortable size. Thebathroom may, if desired, be varied to permita separate W.C. ,

Fig. 9 depicts the plans of a very goodgarage type house, which requires a frontagegreater than the other types ; but, whenconsidered in, relation to houses having" garage -spaces," such extra frontage is ofteneconomical. '

Fig. to is of a pre-war type of plan.Planning detached and other houses presents

no difficulties as regards pre -building, and

I

shor at it and get your husband, or anotherof your menfolk, to do the necessary ; if theycannot, then send your little sketches, boweverrough they be, to the Editor, who, if hethinks the subject good, will have a drawingprepared, your written matter, if necessary,licked into shape, the subject published underyour name, and paid for at usual scale ratesfor non -assisted or assisted short articles.

It happened like this ; just before thepresent war my future husband and I lookedover quite a number of houses with a viewfon his part, of living in, and with my vjew ofmaking a home-two' that can be quitedifferent things. He thotight he knew a lotabout building, and I felt convinced be didn'tknow enough, so that started it. We com-menced on the ground floor (he calls it" groynd storey " which is perhaps correct),called everything well planned and convenient,

projection of mantel and hearth, meant, withthe normal and only practical way of arrangingthe furniture and bed' (as Fig. 12), that thebed would be roasted, and no one could sitor robe or disrobe in front of the fire. Unlessthe carpet (if used) was cut (and therebypartly spoilt) around the hearth, it would haveto be placed one-sided on the floor with mostof it under the bed and none, or little of it,on the fire -side of the bed for feet to restupon. I was told these great disadvantageswere due to a belief that the great lump ofbrickwork looks nicer in the centre of thelength of a wall, and that it is easier andcheaper to place the brickwork where itis usually placed. What all this means to thepractical housewife is of no importance, butan arrangement as shown in Fig. 13, whichis self explanatory, is of much more interest.

(To be continued.)

Outlines of a -few of the many layouts obtainable with pre -built houses.



About AsphaltNature's Own Plastic, and Its ROle in

Modern TimesBy J. F. STIRLING

THE history of asphalt and bitumen takesus back almost to the beginnings ofthe biblical era, to the days when

Noah built the Ark and caulked it with amaterial which, in the written record of theevent, is termed " pitch," but which, clearlyenough, refers to bitumen.

The Tower of Babel record in the Bible isalso associated with bitumen and asphalt, for" slime had they for mortar " (says Genesis),this material, too, constituting a naturalbituminous deposit which was found in thelocality.

The Egyptians were well aware of theproperties of bitumen and asphalt. Amongother things, they used it as a preservativeand a damp-proofer for the mummy -wrappings of their dead. Indeed, the veryterm " mummy " is derived from the Arabicword Mumija, which was a term meaning" asphalt."

It is only within comparatively recent timesthat economic advantage has been taken by

The finished product. Asphalt blocks beingloaded into railway waggons for quick despatch

to factory and other building sites.the nations of the almost unique propertiesof asphalt and bitumen. True it is that the oldRomans knew of bituminous substances, butthey never used them for their constructionalworks. We have, in fact, to travel throughhistory until we arrive at the year.t7i2 beforewe are able to discern the first dawn of thepresent-day world-wide asphalt industry.

In that year ra certain Dr. Eitini d'Eyrinys,a Greek professor living in Berne, discoveredon the Swiss border a peculiar sort of mineralwhich actually burned when it was placed ona fire. This natural product was found toconsist of limestone impregnated with aboutto per cent. of bitumen, and its discoverer wasable to distil a natural oil from it from whichhe afterwards' prepared a mortar -like sludgewhich could be used for cementing purposes.

Considerably more than another centuryhad to elapse before the asphalt and bitumenindustry arose, first in France and then inEngland. At first, artificially processedbituminous products were used in France

for the surfacing ofpavements and forwaterproofing p u r -poses. Gradually theidea of employing oneor more of the manynatural forms ofasphalt and bitumenspread to this countryand, with its eventualacceptance by civilengineers, wasfounded the asphaltindustry of moderntimes.Rock Asphalt

The commencement of manufactUre. Native Cuban asphalt beingcollected from a stock pile for processing.

Bitumen, which is the essential rawmaterial of all our present-day manufacturedasphalt, is a material which occurs naturallyin several forms, and in many different areasof the earth. It is present in the so-called" rock asphalt " which is mined in large

quantities in Sicily,France, Switzerlandand Germany, andwhich, before thewar, was importedextensively into thiscountry, This"natural rockasphalt," as we havealready seen, consistsmerely of limestonerock which, at somefar distant epoch ofthe world's history,has been exposed tothe over -running ofliquid .bitumen(probably ejectedvolcanically from theearth) and which, asa result, has absorbed

a considerable amount of the naturalbitumen. Rock asphalt may contain anythingfrom r to 15 per cent. of extractable bitumenof very high quality.

Another source of 'natural bitumen whichis made much use of at the present day arethe " natural asphalts," as, for example,Cuban asphalt, a black, earthy materialcontaining more than 5o per cent. of naturalbitumen. There is, too, the American" Gilsonite " (named after its discoverer,S. H. Gilson) which is practically zoo percent. hard bitumen, and there is, also," Trinidad Lake Asphalt," a product of aremarkable natural lake in Trinidad which,instead of containing water, contains a specialkind of natural bitumen mixed with clayeymatters and earthy debris. The Trinidadasphalt lake was known to Sir Walter Raleighin Queen Elizabeth's time, it being on recordthat this patron of the tobacco industryactually used Trinidad asphalt for the caulkingand waterproofing of some of his ships.

Millions - of tons of native asphalt have,during the last half -century, been taken fromthe Trinidad Lake. Yet the level of the lakeremains much the same as it originally was,this remarkable lake comprising quite anexcellent example of the " ever -filled purse."

An asphalt manufacturing plant in operation.



A revolving tube

A third class of bitumen of which enormoususe is made in present-day asphalt manufacturecomes from the distillation of crude petroleum,this black, sticky material being the finalproduct of the refining of petroleum. Forthis reason it is known as " residual "bitumen-the bitumen of petrol residues-or else as " petroleum bitumen."

Manufactured AsphaltManufactured asphalt is nowadays used the

world over on account of its truly excellentwaterproofing qualities and, also, in view ofthe cleanly, hygienic, durable surface whichcan be obtained with it either on roads or onfloors or roofs.

Unlike the hard and unyielding concrete,asphalt is " kind " not only"to human feet butalso to the wheels of motor vehicles. Asphalt,besides being absolutely non -penetrable bywater, is thermally and mechanically resilient.That is to say, it is able to take the strains andstresses of heat -expansion and contraction,as well as the varied stresses due to -blowsand mechanical impacts and to vibratorymovements of all kinds.

For these reasons, and for many others,asphalt is nowadays universally in demandfor the making of factory floors, for theconstruction of damp -courses, for the surfacin g

of flat and slopingroofs, for the water-proofing of basementsand foundations, forthe building of A.R.P.shelters and forliterally hundreds ofother vital purposes,in addition to itswidespread employ-ment in roadconstruction.

Asphalt MasticManufactured

asphalt - known i nthe building trade as" asphalt mastic " -comprises - essentiallytwo main ingredients,viz, the asphalticcement " and the

mill in which limestone for asphalt manufacture is " aggregate." T h ereduced to fine powder. asphaltic cement

usually consists. of ablend of bitumens, as, forexample, Cuban bitumenand petroleum bitumen,whilst the " aggregate "comprises merely adefinite amount of min-eral matter, usually Eng-lish limestone and mineralgrit with which the bitu-minous matter or" asphaltic cement " isintimately incorporated.

The process of asphaltmanufacture.. is usuallycarried out in large-mechani cally-stirred,coke -fired iron "pots " or" mixers" which mayhold a charge of anythingup to to or 12 tons ofmaterial.

The carefully blendedmixture of natural bitu-mens is run into themixer, and, subsequently,the various ingredients ofthe mineral " aggregate "are added slowly andin the right proportions.The whole is then

The making of an asphalt road. In the foreground, natural rock asphalt powder is beings,:attered on the road " bed." The illustration shows the'asphalt being raked and tampedinto position,- whilst in the background is seen the mechanical rolling of bitumen -coated

granite chippings on the asphalt surface in order to.Provide, a non -slip surface.

" cooked " for a definite time at a pre-determined temperature, after which themixer is :` discharged " by the simpleprocess of allowing the thoroughly mixedmaterial to run out into a series of cast -steelmoulds of round, hexagonal or triangularshape, in which, it slowly solidifies.

Such material constitutes the asphalt blockswhich are to be seen near the site of buildingand road -constructional operations.

ApplicationsFor use, these blocks are broken up by

means of a heavy hammer and arc flung upinto the " road pot," which is merely asmaller edition of the mechanical asphaltmixer employed during the process of makingthe blocks. From the " road pot " the moltenasphalt is run out into buckets, the contentsof which are flung out on to the floor, roofor other surface which is to be coveredwith asphalt, the hot material being thenspread evenly over the surface by means cfa flat piece of wood provided with a handleand known as a " float." A skilled asphalt -

Asphalt mastic being run out from a mechanicalmixer and cast in steel moulds.

spreader, by means of his wooden ` float,"can bring up an asphalt surface to a perfectlysmooth, satin -like texture which retains itscharacteristic lustre when cold.

Usually, asphalt surfaces arc made up oftwo " coats," each from kin. to yin. thick,the first coat being allowed to cool offcompletely before the second one is spreadon top of it.

Modern research his devised special typesof " acid -resisting " asphalts which arcnowadays extensively employed for the layingof floors in chemical wor cs and in otherindustrial factories. Such asphalt surfacesresist cheirAcal attack to a high degree andremain strong, smooth and durable over longperiods.

Coloured AsphaltPerhaps the most spectacular triumph of

the modern asphalt industry is to be seen inthe introduction and the very extensive use


226

of coloured asphalt. This was the inventionof a young Manchester scientist. Theintroduction of coloured asphalt has broughta new era into the annals of asphalt, for, bymeans of suitable treatment with mineralpigments, the normally black asphalt masticmay be converted into brightly colouredmaterial which is at once fadeless and durableand which, in addition to its pleasing anddecorative appearance, partakes of all theexcellent qualities of the normal blackasphalt.

There are several different methods ofapplying asphalt to roads. A favouritemethod for the asphalt surfacing of busytown thoroughfares consists in grinding upnatural asphalt rock and then running thisout to the road site in specially constructedvehicles which enable the material to bedelivered in a warm condition.

The powdered asphalt rock is quicklyshovelled and raked over the prepared road" bed," after which it is " tamped " downfirmly by means of heavy metal weightsattached to the ends of long poles. Thiscompressive treatment consolidates the warmasphalt rock powder into a firm, homogeneouslayer, which, when cold, provides an enduringwaterproof surface of natural asphalt materialon top of which a light layer of flint or granitechippings, previously coated with bitumen,may be scattered. The surface of the road isthen mechinically rolled, whereupon the" pre -coated " granite chippings sink slightly


into their bed of consolidated rock asphalt, inaddition to adhering firmly to one another.In consequence, a very enduring road surfaceis brought into being, a surface which, inthese days of fast-moving motor traffic, hasthe very decided advantage of being non-skid,even in wet weather.

Natural bitumen, in its many forms, entersinto the composition of a multitude of variedproducts. The ink wjth which these words areprinted contains a little Gilsonite or otherhard natural bitumen to give it " body "and adhesion. Numerous electrical insulatingmaterials are compounded from one type ofbitumen or another. Natural asphalts andbitumens are made up into various water-proofing paints and varnishes. Many kindsof enamel have bitumen or a natural asphaltin their make-up. It is even possible tomanufacture bitumen emulsions, that is tosay, stable mixtures of bitumen and water,which are capable of being sprayed cold. onsurfaces, the bitumen consolidating itself intoa thin film after the water content of theemulsion has evaporated.

Nature's Own PlasticsBitumen and asphalt are truly Nature's

own plastic materials. They have propertieswhich are not to be found in the artificialplastics of our modern era. Yet it is possiblethat bitumen and asphalt will, in post-wartimes, find their way into a number of

April, 1943

these synthetic plastics and, also, into thecomposition of various rubber -like materialsin order to modify and improve theproperties of such substances.

Chemically, bitumen is a mixture ofhydrocarbons ; that is to say, of materialscontaining only hydrogen and carbon. Theprecise composition of the various bitumensis far too complex to permit of chemicalanalysis. For this reason, the technical controlof modern asphalt manufacture is enforced bymeans of physical rather than chemicalmethods.

As a result of the inevitable restrictionof shipping space, the amounts of bitumenimported into this country during the warhave necessarily been diminished. Inconsequence, attempts are being made toproduce manufactured asphalt from thevarious coal -tar and other pitches instead offrom the natural bitumens. Pitch mastics(" British asphalts," they arc sometimescalled) have met with varying degrees ofsuccess. Most probably they will be improvedin the future, yet there is little doubt thatfor the purpose of modern asphalt manufacturethe various natural bitumens reign supreme.There is, therefore, little likelihood thatasphalt and bitumen will ever be oustedfrom their traditional usages by pitchcompositions which, for these purposes, aremerely substitute materials, possessing fewof the durable and resilient -properties of thenatural bituminous substances.

A Synchronous Electric Clock _MotorAFTER a little practice it was found that a

winding speed of about r,000 turns inro minutes could be averaged. It is not,

of course, necessary to count the turns. Thefigure 19,000 turns given earlier was calcu-lated from the length of the average turn andthe total length of wire on the bobbin, this inturn being calculated from the resistance.The winding was found to be asomewhat tedious process but waseventually accomplished after foursittings of approximately an houreach. The end of the winding was

Fig. 9.-A simple form of w

soldered to a connection lead in a similarmanner to the commencement, and anchoredto the coil by binding round with several,layers of the insulating paper firmly fastenedwith Seccotine. Finally a layer of blackvarnished silk insulating cloth was put onand fastened by the same means, giving thecoil quite a professional appearance.

It is not essential to use silk -covered wirefor the coil ; enamelled wire would doequally well, but if this is used it is advisableto insert the insulating paper between thelayers at more frequent intervals. Enamelledwire of this size can often be obtained fromold radio transformers and is quite suitableproviding the enamel covering is in goodcondition.

inder.

By L. F. ROWE

(Concluded from page 187, March issue)Alternative Low -voltage Coils

For those readers who lack the patience towind the coil described above, or do notconsider it worth while, there is the alternativeof operating the clock from a bell transformeror one of the miniature lighting transformerswhich have recently been placed on themarket, and are used for lighting a small bulb

of the flashlamp typefrom a mains lampsocket.

In this case thebobbin can be madesmaller in accordancewith the alternativedimensions given inFig. 8, and is woundwith fewer turns of aheavier gauge wire.If the small bobbinis wound to capacitywith 42 S.W.G.enamelled wire it willoperate the motor oneight volts. Theresistance should bein the neighbourhoodof 725 ohms. Thewriter has not experi-

mented with .coils suitable for lowervoltages, but using the above coil as abasis, . it is suggested that 4o S.W.G. wouldbe suitable for six volts and 38 S.W.G. forfour volts, as many turns as possible beingwound on the bobbin in both cases, usingenamelled wire. When used on voltages ofthis order no insulation is required betweenthe layers, providing the enamel insulation isin good condition.

The WinderThis is of the simplest form, consisting

essentially of two bent -up strip -metal bearingbrackets for the wire -reel and bobbin, screwedto a wood base. The arrangement is shown

in Fig. 9. The handle was cranked to give a'in. throw so that with the forearm resting onthe table the winding spindle could be turnedwith a wrist movement only, thus enabling ahigh speed of winding to be maintainedwithout discomfort. Care was taken to makethe spindles for reel and bobbin a goodbearing fit in the brackets so as to obtain asmooth action, which is essential to avoidfrequent breaking of the wire. The spindlefor the bobbin was made diameter,one end being cranked to form a handle, therest being filed flat each side until it justfitted into the bobbin, which was wedged intoa central position by means of a matchstickeach side between bobbin and spindle. Inorder to provide the necessary slight tensionin the wire, the reel was made a tight fit onits spindle by the use of suitable bushes eachend, and an elastic band was slipped over thespindle and hooked over a screw in the base,

Fig. io.-The com-plete motor after

asseinbly.



the position of the screw being adjusted togive the required braking effect Withoutthis the reel was inclined to overrun andcause the wire to kink and form loops-witha consequent risk of breakage.

AssemblyBefore being assembled, the metal parts a

the motor were polished with fine emery clothand given a coat of colourless celluloselacquer to prevent oxidation. The parts,together' with the coil, were then assembledas shown in Fig. so, and the positions of thepole pieces were carefully adjusted until theminimum air gap was obtained which wouldallow the rotor to spin freely. A trace of lightoil was then put on the arbour bearings, andthe unit was ready for its trials.

With a coil of such small dimensions it isnot possible to obtain sufficient resistance tolimit the current to the desired value whenused on 230Lvolt mains, and therefore aone -watt resistor of the radio type, having ,a value of zoo,000 ohms[ is connected inseries with it. The value of this resistancemay be' varied over wide limits to suit therequirements of the motor, which will varyaccording to the care with which it has beenconstructed. If insufficient trouble has beentaken over the truing of the rotor so that it isnecessary to have a fairly large air -gap, theresistance may have to be reduced to 75,000or even 50,000 ohms so as to allow of theincrease in current needed to produce therequired field strength. If, on the other hand,the air -gap can be adjusted to something inthe order of to -thousandths of an inch, theresistance may be increased in value, and theconsumption reduced, although there is notmuch to be gained by this, as the consumptionis already of negligible proportions.

Current ConsumptionIn the case of the motor described it was

found that satisfactory operation was still

obtained when the resistance was increased to525,000 ohms. Including the resistance ofthe coil (12,600 ohms), the total resistance inthe circuit was then 537,600 ohms, and thetotal consumption less than .4 watt. Thisis the total consumption of motor and resist-ance, and since dr, consumption of each isproportional to its respective resistance, it_will be seen that the energy actually consumedby the motor itself is only 'ft, of the total,

Fig. IL-Details of the starter.

i.e., approximately .04 of a watt, a rathersurprising fact leading one to conjecture asto what microscopic proportions the consump-tion could be reduced if the motor Wereprecision built and provided with needlepoint or jewelled bearings.

While the motor would Ain quite satis-factorily with this high value of resistance incircuit the torque developed was insufficientto stand the jars and shocks sustained whenthe clock was moved (often none too gently)for dusting, etc., which often stopped themotor. Accordingly, the resistance wasreduced to too,000 ohms, at which value thetorque is able to stand normal usage withample margin, the total consumption thenbeing less than half a watt.

If a low -voltage coil is used it is, of course,not necessary to use a series resistance, as itis comparatively easy to provide sufficientresistance in the coil itself.

The StarterWhen the motor was fitted in the clock case

a simple starter was provided, so constructedthat it is impossible to start the motor in thewrong direction. Details are shown in Fig. 1t.It consists of a spring -loaded spindle with anarm arranged to engage in the teeth of thewheel driven by the motor pinion whenthe starting knob is turned. On releasing theknob, the arm on the spindle drives the rotorvia the pinion and gearwheel, until the armreaches the end of its travel, when it disengageswith the teeth of the wheel, leaving it free torotate under the action of the rotor, which hasby then dropped into its synchronous speed.The strength of the spring is adjusted untilit is sufficient to bring the rotor up tosynchronous speed without giving a violent" kick." The driving arm which engages with'the teeth of the gearwheel consists of a shortlength of spring steel wire bent to the requiredshape and held in position by threadingthrough two small holes drilled in the spindle.The end of -the wire was bent over as closeto the spindle as possible, to secure it firmlyin place. The starter was screwed to the woodcase of the clock, as can be seen in Fig. 2, but

s it can, if desired, be mounted in a positionconvenient to the gear train by means of ametal bracket attached to the clock frame ifnecessary.

Fig. 2 also shows the miniature two -pin plugused for connecting up. This is a Belling -Leeclock connector, although any small two -pinplug would do. The back plate of the clockwas drilled to suit the plug and arranged sothat it was necessary 'to withdraw the plugbefore the back plate could he removed, thusproviding a safety feature. The terminalblock seen above the plitg was only providedfor convenience of connecting up whenexperimenting with various coils, and may hedispensed with, the coil leads being connectedstraight to the two connector_ pins via theseries resistance if the mains coil is used,the resistance also being housed in the clockcase.

RA.F.'s New Twin-engined BomberThis illustration of a Mosquito in flight shows the sturdy appearanceof the R.A.F.'s new light bomber. It is powered by two Rolls-Royceengines, driving' de liavilland three -bladed hydromatic propellers.The aircraft has a surprising speed, and a range probably exceeding .athousand miles. The armament consists of four 20M.M. cannon, and

four .303 machine-guns.


228 NEWNES PRACTICAL MECHANICS ApriI, 1943

The

Early' Electric Supply InstallationsIN the first lecture reference was made to

some of the early installations of arclamps for lighthouse work and for street

lighting. As these lamps were not suitable forinterior use, progress in the field of electriclighting generally was hampered ; and soinvestigators then sought to " divide theelectric light." This problem was solved in1878 by making use of incandescent glow

' lamps, connected in parallel. This madepossible the electric lighting of domesticpremises and the interiors of public buildings.

Many installations using Swan lamps weresoon in being ; among them was the lightingof the Savoy Theatre, London, in 1881. Thecurrent Vas obtained from Siemens alternatingcurrent generators. In the same year a smallgenerating station was installed and operatedby Siemens Bros. and Co., at Godalming inSurrey. The power was developed by makinguse of a waterfall on the River Wey. Certainstreets were lit by both arc and incandescentlamps, which were connected to cables laidalong the street gutters. As there seemed tobe no prospect of a demand for electric lightingby the householders in the district, the supplywas discontinued in 1884.

At the end of the year 1881, Mr. RobertHammond went to Brighton to stage anexhibition of the Brush arc lighting system inthe town ; this proved a success and resultedin the formation of the Hammond ElectricLight Co.," which, in February, 1882, was'giving supply to 16 arc lamps for illuminatingthe premises 'of certain shopkeepers. At thesame time, the company were offering tosupply current to any prospective consumers.

In January, 1882, Edison's agent in Londonobtained the permission of the city authoritiesto undertake the lighting, of Holborn Viaductand some of the neighbouring streets bymeans of Edison incandescent lamps. Steam -driven dynamos generating at 110 volts were

- installed in a building near the east end of theViaduct, and the main cables were laid alongthe existing subways. From these cables,services. were taken to most of the premiseson either side of the street. Soon afterwardsthe supply was extended to the General PostOffice in Newgate Street. It was provided inthe agreement between the two parties thatthe Viaduct and the streets were to be lighted,free of cost to the City, for a period of threemonths. The supply was commenced inApril and, at the end of the three months'trial, fresh agreeffients were made and theservice continued until 1886, when the stationwas shut down. ,

In 1882 Edisbn planned his first installationfor New York City. He decided that anunderground system of distribution wouldbe necessary, and in September of the sameyear a supply was given from Pearl StreetStation.

In 1883 Sir Coutts Lindsay put down astation for lighting the Grosvenor Gallery inNew Bond Street, London. The plant wasintended originally to supply arc lamps inseries, and consisted of Siemens type engine -driwn alternators generating single-phasecurrent. Not long after it had been incommission, applications for a supply ofelectricity were receiwd from ShOpkeepersand residents in the neighbourhood. Theseapplications were met by installing atransformer in the house of each consumerand by giving a supply at 2,000 volts by

7Distribution of Electricity

Second Cantor Lecture Given Before the Royal Society of ArtsBy E. AMBROSE, M.I.E.E.

(Continued from page 194, March issue)overhead cables, supported from iron poleson the roof tops. The primaries of all thetransformers were connected in series, theconsumers' lamps being connected' tothe secondary. The demand from outsideconsumers continued to grow, and so a largerstation was constructed and further overheadcables and transformers were installed, asbefore, with their primaries in series, anarrangement suggested by Gaulard and Gibbs.Trouble was soon experienced with thisarrangement, and S. Z. de Ferranti, then ayoung man, was called in to advise. Heentered the service of the Grosvenor GalleryCo., and one of the first things that he didwas to replace the series transformers by othersdesigned to operate in parallel across themains and so introduced a method whichremains to this day: He replaced the Siemensalternators by others of his own type. Later,

Fig. 5.-A so -kilowatt steam -generating set used by one of the earlyelectricity supply companies.

a new company, called the London ElectricSupply Co., was formed to take over theGrosvenor Gallery station, and progress wasmade. Subsequently a power station wasbuilt at Deptford for the purpose of sendingcurrent at high voltage to London. Ferranti,who was responsible for the installation,chose 10,000 volts for the transmission. Hedesigned and built the cable and thetransformer for stepping -up the voltage fortransmission and for stepping -down again atthe receiving end. By laying the cablesunderground along the railway track betweenLondon and Deptford, he was able to avoidcertain provisions of the Electric LightingActs.

Electric Lighting ActIn August, 1882, the first Electric Lighting

Act was passed by the House of Commons.This Act conferred powers on municipal andother undertakers to break open streets for thepurpose of laying mains, and gave powers tolocal authorities to 'raise loans in connection

with the supply of electricity. The Actprovided that application fo4 the necessaryprovisional orders or licences to supply wereto be made to the Board of Trade It alsoempowered the local authority, at the end of21 years, to purchase the undertakings of theenterprising supply company, or so much ofit as lay within the jurisdiction of the authority,without having to pay anything for thegoodwill or increase in the value of theundertaking. The onerous character ofthe purchase clause produced universal -dis-satisfaction and this was reflected in the veryfew applications that were made to the Boardof Trade.

The development in the supply of electricity,however, was not altogether held up, becausewherever a company could obtain permissionof the local authority to erect mains overhead,it could carry on its business without referenceto the Act. This was done by the HammondElectric Light Co. at Brighton in 1882,the Grosvenor Gallery Co., London, in1883, and at other places. At Hastings andEastbourne, cables were laid in the streets'

with the assent of thelocal authorities,, with-out reference to theAct. The KensingtonCourt Electric LightCo., started by ColonelR. E. Crompton, wasable to carryon withoutregard to the conditionsof the Act by obtainingpermission of theKensington Court Co.to lay mains in thesubways that existedunder the roadways.Fig. 5 illustrates a50 -kilowatt s tea m -generating set of thetype installed byColonel Crompton.

In the meantime,efforts were being madeby influential peopleto obtain the repeal ofthe 21 years' purchasedause. Ultimately, anddue mainly to theefforts of LordThurlow, an Act was

passed in 1888 which, amongst other pro-visions, extended the period of security to thecompanies from 21 to 4.2 years. The effectof this concession way immediate andmanifested itself in the promotion of newcompanies and applications for the necbssarypowers to supply electricity in various areas.

Public SupplyGodalming may claim to be the first place

in which a public supply was given, althoughHolborn Viaduct was the first place in whicha supply was given for both public lightingand for private houses. Both of theseinstallations, however, existed for only a fewyears.

If consideration be given only to thoseundertakings which have had a continuousexistence, then priority should be given toBrighton. At first, the supply, which wasprovided by a special type of dynamo capableof delivering direct current at a high voltage;was used for arc lighting only. All the arclamps supplied by any one machine were



connected in series, so that the -same currentflowed through each lamp. Soon, however,Mr. Wright, the station engineer, devised ascheme for supplying incandescent lampsfrom the arc circuits. The supply was givenby overhead conductors, and the systemcontinued until 1887, when it was changedover to single-phase alternating current,generated at 1,800 volts, and reduced to toovolts for the consumers by means of localtransformers. Subsequently, a further changewas made, in 1891, when the municipalauthority started a system of direct currentsupply at 115 volts. Following the completionof arrangements for the purchase of .theoriginal undertaking, the consumers weretransferred to the mains of the corporation.

D.C. SystemsIn most of the earlier methods of distribution

a direct current supply was given, and, becausethe incandescent lamps then available wereconstructed for a pressure not exceeding toovolts, the operating voltage of the system waslimited to that pressure. The initial step wasto run one or more pairs of main cables,radiating from the generating station, and totap off from these wires two conductors toform a branch at the point where the supplywas needed. Across these branch wires wereconnected the lamps or other consumingdevices. With this arrangement, the supplyto* each branch was independent of the rest,but, with a common main and separate

branches a fluctuation of voltage wasintroduced, owing to alterations of currentflowing in the main cables. In addition, avoltage drop would occur proportional to thecurrent density and the length of mains. Oneway to reduce this drop would be to increasethe doss -sectional area of the conductors, butthis would mean increased capital expenditure, apart from the difficulties involved in makingthe change. A less expensive method wouldbe to install, in the first instance, mainstapered in section. In other words, the sectionof the conductor which, at the generatingstation end would be the maximum, would bereduced -by joining on mains of a somewhatless cross section, and, as the distance fromthe station end increased, conductors Oa stillsmaller section would be joined. Thismethod had the disadvantage that theconductor at its smallest section would forma path of high resistance were it ever necessaryto connect the ends of two pairs of radialmains for the purpose of feeding back in theevent of a fault on a main near the station.

The introduction of incandescent lampscapable of operating at 200 to 220 volts was auseful step forward, because it enableddistribution on the two -wire principle to becarried out at double the pressure, and withhalf the current for the same power required.

Three -wire DistributionIn 1882, long before the advent of the 200

volts incandescent lamp, Dr. John Hopkinsoninvented a three -wire method of working,and in the same year this method was invented,independently, by Edison in America. In itsoriginal application, the use of the third wirewas obtained by coupling together twosimilar dynamos in series, the positive and

' the negative cables being connected to theouter terminals of the set, while the third ormiddle wire was connected to the junctionof the two inner terminals (see Fig. 6). Ifeach dynamo were capable of generatingcurrent at too volts, then the pressure betweeneach outer and the middle wire would be toovolts, and there would be zoo volts betweenthe two outer wires. With this arrangementthere are the advantages of working at anincreased voltage, with the consequentreduction in the cross section of the cables,and still retaining the low voltage lamps. If anequal number of too -volt lamps, all of thesame rating, are connected between each of

the outers and the middle wire, then nocurrent flows back through the middle wireto the generators; but there is certain to besome condition of loading when there are moreon one side than the other. If the load on'thepositive side is greater than that on thenegative side, the difference between the twocurrents will flow along the middle wire backto the dynamo on the positive side; a similareffect would take place if the greater load wasconnected to the negative side. Since thereis current flowing through the middle wireonly when there is an inequality or unbalanceof load, it is usual in practice to make its crosssectional area not more than one-half of whateither of the two outers be, although, insome instances, a cross section equal toone quarter of that of an outer main has beenused. The connection of consumers is carriedout in such a manner as to secure as perfect a

Fig. 6.-Diagram of the direct -current three -wire .method:

balance or equality of load on the two sides ofthe middle wire as possible. Ordinarily,consecutive consumers would be connectedalternately across the positive and the negativesides, two -wire service being used. 'But forlarge consumers a three -wire service wouldbe used, the consumers' wiring would bedivided into two independent circuits, asnearly equal as possible, one of the circuitsbeing connected between the positive and themiddle wire, and the other between thenegatiVe and the middle wire.

Five -wire DistributionThe next development was the introduction

at Manchester, in 1893, of the five -wiredistribution net-work with 400 voltsbetween the outers.The distributorswould consist o f fivewires, one of thembeing the equivalentof the middle wirein the three -wiresystem. Serviceconnections couldbe made on eitherside of the middlewire to give too or20o volts. A con-nection across theextreme outerswould give the full400 volts. Thissystem operated forsome years in Paris,and for perhaps alesser period in Manchester. It was a systemwhich gave great flexibility of distribution,but it was also complicated, and great carewas necessary for its operation andmaintenance.

Fig. 7.-Diagram of- 3 -phase four -wire

method.'

A.C. SystemWhilst many of the supply engineers had

been developing the direct -current system ofdistribution, others were putting in networksfor alternating -current working. The

pioneer system of alternating supply consistedin running several independent alternators,each driven by its own engine, the distributionbeing usually effected by a number of high-pressure mains, from which branches, orservices, were tapped off to feed smalltransformers fixed. on consumers' premises.This system was adopted in 1889 by theHouse -to -House Eiectric Light Co., Ltd.,later to become the Brompton and KensingtonElectricity Supply Co., Ltd. Single-phasecurrent was supplied at 2,000 volts andtransformed down at the consumers' premise§to too volts. A similar system was used atother places where the primary voltage wasr,000. As the system involved a largecapital outlay in small and inefficient trans-formers, it soon gave way to one in which alow-pressure network was fed by largertransformers installed in substations.

Three -wire A.G. Distribution -A three -wire alternating -current supply can

be given from two similar transformers, iftheir primaries are both fed from the samesource, and their secondaries are connected inseries. The third or middle wire would beconnected to the junction between the twosecondaries whilst the outer conductors wouldbe connected to the two remaining terminalsof the combination. The same remarks withregard to balancing the load applies as to thedirect -current system. About the year 1899a few 2 -phase systems were being installed.In general the method was to install twogroups of single-phase transformers in asubstation, and to feed the primaries of onegroup from one phase of a high -voltage two-phase supply and to feed the other group fromthe second phase.

The low -voltage mains, consisting of twoconductors, were connected to the secondaryof the transformers and formed separatesingle-phase circuits to which the consumers'wires were connected. To maintain, as nearlyas possible, a balanced load on the complete

successive houses to alternate phases. Theintroduction of the two-phase system pro-vided means for the development of a moresatisfactory motor. If, therefore, in a districtin which a single-phase supply had beenoriginally installed, there arose a considerabledemand for motive power, the change fromsingle-phase to two-phase could be effectedwithout replacing any of the original mains.

Three-phase Four -wire DistributionEarly in 1900 the three-phase four -wire

method of distribution was being installedfor new supply areas, and in many instancesit has replaced existing networks originallyput down to operate with three wires directcurrent. In this method the three line wiresare connected to one end of the three secondarywindings of a three-phase transformer, theopposite ends of the same three windingsbeing connected together ; this forms whatis called the star. connection. The fourthwire is connected to the star point, and,together with the three line wires, forms afour -wire circuit from which a supply isgiven to the consumers (see Fig. 7). Thevoltage between any one of the three-phasewires and the fourth, or neutral wire, isarranged to correspond with the normal lampvoltage, usually 230 volts, whilst the voltagebetween any two of the phase wires would beA/3 times this value, namely 400. (Thiscan be verified by drawing two lines ofequal length with an angle of no deg. betweenthem and measuring the length of a lineto form the third side of the triangle.)

All service wires to domestic premises forlighting would be connected between oneof the phase wires and the neutral wire, butfor three-phase motors the three-phase wiresonly are required.

(To he continued)



Projectin Time on the CeilingAn Ingenious Watch -stand which Throws an Enlarged Illuminated Image of a Watch and

THE object of this contrivance is to throwan illuminated image of your watch,much enlarged, on to the ceiling, so

that as you lie in bed wondering whether it istime to get up, you can see the time with aminimum of inconvenience simply by pressinga pear switch, which may be kept under thepillow. This switch is connected by means ofa yard or so of " flex " wire to the apparatus.(shown in Fig. r), which stands upon a bedsidetable. The watch is simply hung up on itshook, and when the button of the pear switchis pressed two small lamp kulbs, worked froman ordinary flashlamp battery, shine on to thewatch.

Focused on the CeilingA lens arranged in front of the watch face

focuses a picture of the dial and hands on' theceiling, the light being directed upwards bymeans of a mirror. Focusing is done bysliding the watch support to and fro until asharp image is thrown on the ceiling ; oncethis is done the focus is always correct, unless

Mirror

Hinged lid '

SeX32xr

52Sliding, Coker4.x 21x d"

Fig. i.-Sectional viewsa watch of different thickness is used, orunless the distance to the ceiling is altered byplacing the apparattis on a higher or lowertable.

Wooden Casing and LensThe body of the apparatus should first be

made of gin. wood to the dimensions given inFig, 1. If wood of a different thickness is used,be careful to modify the dimensions wherenecessary to allow for this. The sliding coverfor the battery compartment works in agroove formed by tacking -gin. wood onto theside walls, the space between two pieces ofthe gin. wood forming the groove. Mostamateurs will find this easier than cutting thegroove.

For the lens use a small reading -glassabout I tin. diameter and about 4in. focus.Such a glass in a celluloid holder can usuallybe obtained from a chemist's shop. If one ofthese is used the holder should be discardedand the plain glass fitted into place, as shownin Fig. t, by means offour small clips of brassor thin wood. The lens hole should, of course,be slightly smaller than the lens.

its Time on the CeilingThe Watch Support

This is quite a simple affair. It is clampedin position by means of a single bolt with aknurled nut, and this bolt works in a slot inthe floor of the watch compartment so thatthe watch support can be moved backwards orforwards to its correct location. 'A small nickshould be cut across the top edge for the chainwhich hangs outside, this avoids detachingthe watch from the hain every night. Careshould be taken when fixing the hook that thecentre of the watch comes right opposite thecentre of the lens.

Two ordinary flashlamp bulbs are used forillumination, one on each side. They shouldbe about halfway between the lens and thewatch ; if too close to the watch illuminationwill be uneven, while if the lamps are too faraway the light may not be bright enough.

Two suitable screw lamp holders can beused, or you can fix the lamps as shown inFig. a. This sketch explains itself, and thearrangement is quite simple and effective. Aflat piece of bright tin screwed to each side of

the watch compartment, as slidwn inFig. t, will make a good reflector andimprove the illumination.

24)-

of the complete apparatus.

The MirrorThe mirror is arranged opposite to the lens

on the outside and is held in position by meansof the support shown in Fig. 3. This is cutout of thin sheet metal bent to shape andscrewed into the required position. Themirror itself should be cut to the correctsize-by means of a wheel cutter or a diamond-after the support is screwed into place, andheld in position by means of the two lugs

Fig. 2 (left).-How thelamps are

fixed.

F i g.L amp Section of

bottom com-p al- t m en t,showingbattery con-

nections.

shown in Fig. 3, which are bent over the edgeof the mirror, as indicated. The mirror shouldbe of good quality flat glass-some cheapmirrors have a more or less undulating

45*

Holesfor screws

Fig. 3.-The metal bracket for holding themirror.

surface, which, in this case, would spoil thesharpness of the picture on the ceiling.

Two terminals are required, and theseshould be fitted into the position shown byFig. t, while Fig. 4 is a part sectional planshowing how the battery connections arearranged. The short brass strip from thebattery is bent so as to press directly on to oneterminal, while the other battery strip is bentover to press against a special contact plate.

ConnectionsWiring up is the final operation. Use

insulated wire of about 22 gauge, and. becareful to scrape off the insulation at theconnections so that a good metal -to -metalcontact is obtained. Connect a wire to each ofthe brass angle pieces which press against thecentral connections of the lamps, run thesewires neatly through the holes in the bottomof the watch compartment, and connect theother two ends to the contact plate shown inFig. 4. The connections may be made simplyby pushing the bare ends of the wire under theplate and screwing the latter down tightly.Now connect a wire to each of the strips whichclamp the lamps in place (Fig. a), and runboth of these wires to the terminal (outsidethe battery compartment).

This completes the apparatus except forfinishing, and this is left to the reader's ownideas.

If it is possible to place the projector ona permanent site, so much the better, asthe operator then becomes used to lookingfor the image on one part of the ceiling.Don't place it tight up against a wall.

Terminals

Battery



PhotoAraphinA TreesNotes on Selection of Subject, Light and Shade, and Sky Effects

By JOHN J. CURTIS, A.R.P.S.

FOR the second of my series of" specialised " subjects I have selectedone which has always had a particular

appeal to me, therefore the hints which Inow give you are of my own personalexperiences and feelings. Although theremay be some with which you do not altogethgragree, yet the reading of these notes maygive you a different outlook on one of Nature'sspecial subjects which, hitherto, may not havereceived much attention from ypu, probablybecause you have not considered it from thepictorial angle. .

You who are fond of walking tours orhiking excursions know that the reason whyyou like this type of exercise or recreation isthat it gets you into the country, away from" bricks and mortar " ; you realise that whenyou are tramping through the fields or lanesor over the hills you are witnessing an ever--changing panorama made,up of items whichin themselves are things of beauty, and ajoy for ever. It is not surprising, therefore,that large numbers of amateur photographersare keen walkers.

Nature gives us itS own idea of colourschemes, its true conception of harmony, acorrect rendering of perspectives and quitefrequently we can find perfect composition ;with such a combination of the essentials weunderstand the reason why so many morespools of film are exposed on subjects in theirnatural surroundings than on the artificial orman-made objects.

Selection of SubjectWe have to admit that there are many

times when it is quite impossible to reproducewith a camera all that is seen with the humaneye, and there are also many occasions whenthe camera will persist in seeing more thanwe wish it to ; we would like to avoid this orthat branch of a tree, that interfering bush orold tree trunk, and what a pity that horse isgoing the wrong way, or how very muchbetter if that path was not so straight. Yes,the artist has a pull over us in this respect,he can add or leave out anything he wishes ;still, we are often tempted to try a " shot,"hoping thk something good can be made ofit when it reaches the enlarging stage. Youcan, however, have the satisfaction of knowingthat when you have reached this stage ofdiscrimination in the selection of your subject,you have made a very decided advance inyour hobby, and are beginning to show aknowledge in what to take and what not to,and your results should soon be approachingthe too per cent. pictorial standard.

I have heard it said that an amateurphotographer sees twice as much as hiscompanion who has no camera, and I wouldnot hesitate to put the difference as muchmore than twice, and to illustrate this pointhere is a true story. I was with a party ofabout 3o ramblers, the time was late autumn,and there were only about half a dozencameras on this occasion, but everyone was areal nature lover; I turned aside to lookmore interestedly at a bush on which werehanging some hundreds of Nature's jewels inthe form of drops of moisture which were onpractically every point of each twig and onthree or four large spiders' webs recentlywoven. I got my camera in position for thebest lighting; this took a few seconds only,but sufficiently long to make the rest of theparty curious as to what I had discovered.They retraced their steps and everyone was

thrilled at the beauty of the " fairy tree," andthe other cameras were soon making recordsof this simple but beautiful piece of Nature'shandiwork.

Varieties of TreesIf I am ever fortunate enough to live near

a forest or a large wood where there happensto be a number of various kinds of trees of agood size, I am certain that nothing will

Autumn in the woods.

prevent me from making a photographicstudy of them at different times or seasonsof the'year, spring, summer, etc., in sunshine,mist and rain. I would want to capture theirmoods, for I am told that it is possible todetect every mood in trees. Presumablyone has to use a good deal of imagination, butI pass on this idea for any of you to put intooperation, feeling certain that you will find ita most fascinating addition to your hobby ;besides proving a " specialised " subject towork on, it will undoubtedly produce for youa most interesting and instructive collectionof negatives not only for print -making butfor a really good lantern lecture.

Some few years ago there was a mostinteresting exhibition in London of photo-graphs of trees, mostly of single trees, but itwas surprising how very pictorial most ofthem were, and yet not so surprising whenone really studies the subject ; many of usare familiar with one or more fine specimensof old beeches, with thick, broad bases, andtrunks gnarled and knotted as a result ofold age. What a picture when the sun is in theright direction for enabling the details of thattrunk to be captured by the camera. Howeveryone admires the silver birch with itsgrace and stateliness, and the fine lines of

its branches and the twinkles which can beseen when the wind catches its myriad of smallleaves ; what a camera study ! Anotherpicture tree is the elm, especially when inearly leaf or when the winter has removedall the leaves, and there is only the finelace -like tracery of its thousands of smalltwigs ; what a grand sight is a row of elms,heads erect and standing in regular formationup the hill. Catch this when the sun is sinking

and throwing long shadowsacross the grass of the field,or, if they look better fromthe other side, get out earlyand " shoot " them withthe early morning sun. Ithink any such row of treeswill make a picture of whichyou can be proud. . Theoak is not, in my opinion,such a photographic treeas some others ; it certainlymust be studied to get itat its best, and I think thismay be when it is fairlyfull of acorns, and theleaves just beginning toturn. Somewhere in theautumn is about the besttime, but I must agree thatin the spring when its leavesare fresh, small and not toothick, it does look verypicturesque, but study thelighting before making theshot.

What about that mostpopular of trees, the horsechestnut ? Singly or inavenues it offers countlessopportunities ; in the springwhen its buds are justbursting and then a littlelater, you get the beautyof those charming spires ofblossom cheering every-body with the fact thatsummer is close. A fewmonths later we find thosesame trees with their fruit

balls and fewer leaves ready for furtherfilms to be exposed.

We can go on adding to the list, but onemust say something about that period of theyear when it seems difficult to select any onetree that is better than another. It is the -timewhen we wish to find our way into some fruitorchard where every tree is a picture. Howcan we resist taking a cherry or apple tree

_in blaiSom ? You can take a single bunchof the flower, a sprig or a branch or the wholeof the tree and you are certain of a resultthat will give pleasure, and add charm toyour collection of prints. This is also the timeof year when small fleecy clouds are quite acommon feature, and just what you want fora background to that branch or spray ofblossom. Put an X2 filter on the lens to ensurethe small cloud being in the picture ; if youwould like something rather more decorative,hang a piece of black velvet, your focusingcloth will do, on the wall, and place the sprigof blossom on this and then make the exposure.If you have artistic taste in the arrangingof flowers in vases, you might secure somevery beautiful results with fruit blossoms.

Light and Shade '

To return to trees generally, you will find

_


232 NEWNES PRACTICAL MECHANICS

that it is essential to do some experimentingin order to find the right light for giving atrue rendering of the tone values of thelarge range of colours, 'or' shades of colour,which are to be found in almost all trees ;you must not have heavy shadows void ofdetail. Those exquisite details of light andshade on the main trunk have got to berevealed in your print, and do not take yourpicture without some foreground, unless youwish to give the impression that the tree isgrowing in a small back garden. If it is alarge oak or cedar; then give it space, whichmay mean Cooking around for another treeto take, but -I am sure it is a -mistake toattempt too much tree, and not enoughground.

If you are able to get the whole of thetree into the picture, -be careful to study thesky. I do not like bald skies, even for treestudies, and I am sure you will prefer to havea cloud just passing across the sky so that itwill help you to bring out the detail of those

top .branches. Here again the 2X filter willhelp you.

I want it to be understood that I amnot too keen on the use of filters, -becauseI think that this subject is not sufficientlyunderstood by amateurs, and that thetendency is to -overdo their use. Some ofyou may have seen results which in myopinion are the result of using a too deepor wrong colour filter, as fot instance a whitecloud overpowering all the other details of thephotograph, and backed by a terribly blacksky. Well, it may be pleasing to some, but Icannot imagine any of our painter artistsproducing such a result.

BackgroundI have ' suggested waiting for a small

fleecy cloud as your background, and I also.want to advise you not to be too keen ongetting every little detail perfectly needlesharp. It is better to avoid strong lighting,especially if you are surrounded with fairly

April, 1943

heavy and deep shadows. Then there is thatstrong lighting which one sometimes finds'inthe background, due to a small clearing,where the sunlight is stronger than at theactual spot you are shooting ; you mustbe your own judge, but if the contrast isvery great, do not waste the film. In all thisclass of work there must be no strongcontrasts, but rather a long range of tonesfrom black, through the greys, to the white,and if these are to be found in the subject,and your exposure and development is correct,then you will be certain of a good picture oftrees.

When judging a competition recently Iwas very pleased to note that quite a numberof the entries were tree subjects, but it wascertainly disappointing to see the many waysin which the competitors had " missed theboat"; some had included figures, othershad not troubled to clean up the foreground,and other's through not noticing the lighthad got " soot and whitewash " prints.

The Story of Chemical DiscoveryNo. 21.-Modern Views on

THE history of atoms dates back -to theearliest records of human thoughtand philosophy. For some strange and -

apparently intuitive reasons, thinkers of allages and civilisations sea constitutionallyto have been imbued with the idea thatmaterial things are not continuous but arediscrete or partidlet1 in their inherentmake-up.

By this is meant that all existing matterdoes not, in its inner structure, form onecontinuous medium but that it is essentiallyan agglomeration of fine, ultimate particlesto which we nowadays refer as " atoms."Matter, it has always been believed, hasa " grained " structure, not a smooth,continuous one, if, indeed, the latterwere theoretically possible.

The old Greeks, and even the Hindus beforethem, taught that matter is atomic in con-stitution, that the atoms of material things are separated by void spaces, and they even wentso far as to advance the -theory that the atomsof things are in a state of perpetual motion.

It was from these ancient ideas that RobertBoyle, the seventeenth -century " Father ofChemistry," and, at a later date, the perhapsstill more famous John Dalton gave tochemical science its working hypothesis ofatoms which resulted in the famous " atomictheory " upon which chemistry was and stillis, to a great extent, based.

John Dalton in the early part of the lastcentury considered the atoms of materialthings to be round, hard, impenetrable par-ticles which were eternal, indestructible andmore or less completely unchangeable. Atoms,according to. Dalton's theory, were -to beimagined as, ultra -microscopic billiards balls. -

The Dalton theory of atoms did good ser-vice to chemistry if 'only on account of the'fact that it served to emphasise the chemicalconception of an clement, and the varyingratios of an element's combination or unionwith other elements. It was, in fad, upon the*Daltonian conception and " laws " of atomsthat the vast edifice of our present-daychemistry was reared.

Vortex AtomsTowards the conclusion of the last century,

however, there came a time when scientificthinkers were no longer entirely satisfied withDalton's notions regarding the natUre ofatoms. Lord Kelvin, the famous electricalexperimenter, for instance, suggested thatatoms were anything but hard, impenetrable

the Problem of Atom Structure and the Make-up of Matter

Lord Rutherford.bodies. He putforward his " vor-tex " theory ofatoms, whichtheory practicallyannihilated t h esupposed solid-arity of the atom,for Lord Kelvin'satom was nothingmore than a merewhirl or vortex in.the ether of space,a mere " smoke -ring "in the ether.Since the etherwas considered tobe absolutelyfrictionless, thisvortex motion,after having beenonce setup, wouldpersist for ever.,a condition which,according to LordKelvin, would be

The cyclotron.

sufficient to account for the assumed in-destructibility of the chemical atom..

Lord Kelvin's atom had a few earnestbelievers, but, on the whole, the Kelvin" vortex " theory was far too unsatisfactoryfor the chemists, and for even the physicistsof the day, so that, for want of somethingbetter, most of the Victorian scientific workers,and particularly the chemists, stuck resolutelyand determinedly to their traditional concep-tion of the Daltonian and the pre-Daltonianatom.-- As far, back as 1815 an English physiciannamed Prout put forward the theory that theatoms of all the different elements were formedby a peculiar condensation of hydrogenatoms.Hydrogen atoms, on Prout's theory, were thereal, ultimate atoms. The atoms of the otherelements, as, for example, the atoms of lead,copper, tin and iron, were all agglomerategroups of hydrogen atoms.

Many experimental facts proved Prout'shypothesis to be untrue, yet, to us moderns,the theory is of great interest if only in view ofthe fact that it manifested the idea of therebeing one basic form of matter throughout thewhole gamut of the chemical elements.

When, about 1896, the first radio -activesubstances were discovered and, closely follow-ing them, the electron was revealed, it came tobe seen that, despite the non -validity of

An electro-magnetic machine of high power for producingartificial radio -active atoms.


April, 1943 NEWNES PRACTICAL MECHANICS

An atom of beryllium metal. It embodies acentral nucleus having four electrons revolving

round it in the manner shown.

Prout's theory, the atoms of matter do reallycontain at least one basic constituent, for itwas quickly ascertained that the electronswhich were derived from widely varyingchemical elements were all the same inproperties. That is to say that such electronswere all almost inconceivably minute fast-moving particles of negative electricity, which,owing to their very nature, had propertiespeculiarly their own.

The discovery of the radium elements gavethe final blow to the Daltonian theory of atomsas being hard,_ solid, billiards ball -like bodies.It became apparent that electrons are actuallyparticles of negative electricity which aredivorced from matter, and that small, indeed,as the atoms of matter are, the electrons arestill very much smaller.

Atomic DimensionsTo take a concrete instance. The weight

or, rather, the mass of an electron is 1/1,800of the mass of a hydrogen atom. Yet, undernormal conditions of pressure and tem-perature, the' diameter of a single hydrogenatom is about one hundred -millionth of acentimetre, its weight being rather consider-ably less than one millionth of a gram.

Here were some tangible facts, derivedfrom conclusive experiments which JohnDalton had never even dreamed of. Atomscould be measured, and they had been provedto contain within them electrons which areparticles of negative electricity.

But because experiments showed clearlythat atoms are perfectly neutral bodies it wasonly logical to conclude that, in addition toelectrons, atoms must contain particles ofpositive electricity to neutralise the electrons,or negative particles.

This was the reasoning uporr which LordRutherford had worked when, in 1911, he putforward his modern theory of the chemicalatom. According to this theory, every atomis composed of a central nucleus whichconsists of one or more particles of positiveelectricity, or protons, as they are called.Around the central nucleus revolve at highspeed and at varying distances the atom'scomplement of electrons, just as the earthand the remainder of the planets rotateregularly around the sun.

Indeed, to a large extent, the sun and theplanets present the Rutherford model of theatom upon a gigantic scale.

The central nucleus of protons, accordingto the Rutherford theory, embodies almostthe entire mass or weight of the atom,for the revolving electrons are practicallyweightless.

The simplest atom, that of hydrogen, ismade up of a central nucleus of one proton,around which revolves one electron. As theatoms of the chemical elements becomeprogressively heavier the number of protonsin the atomic nucleus increase, with acorresponding increase in the, number ofrevolving electrons. Thus, an atom ofhelium has two protons and two revolving

An atom of helium. It comprises a centralnucleus with two planetary electrons.

electrons, whilst an atom of lithium containsthree protons and three electrons. Eventually,we have the element uranium, at the bottomof the list of elements, the atoms of whichmetal each have 92 protons and 92 electronsrevolving in complex orbits around theatomic nucleus.

Professor Langmuir, the American tIteoristof atoms.

Such, in the n-jain, is the Rutherfordtheory of atoms. Whatever its deficienciesmay be, it serves to show us that, unlike theDaltonian atom of hard, impenetrable pro-perties, the actual atoms of matter, althoughthey are extremely stable and enormouslystrong in a mechanical sense, are definitely

Lord Rutherford's idea of a, lithium atom.It comprises a central nucleus with three

revolving electrons.

233

anything but hard and impenetrable. Indeed,modern knowledge has revealed the fact thatthe greater part of the atom is mere emptyspace, and nothing else. The atom's pro-perties of weight and mass reside in its smallbut heavy nucleus, whilst its chemical pro-perties are formed by its system of revolvingelectrons.

Lewis-Langmuir TheoryTwo American chemists, George N. Lewis

and Irving Langmuir, put forward analternative theory of the atom which hasreceived a good deal of attention. Accordingto these workers, the atom contains a nucleusof protons, whilst the electrons are placedaround this nucleus at given points on con-centric imaginary envelopes or shells. Theseelectron " shells ' comprise imaginary planesor layers upon which the electrons exert theirinfluence. The various electrons are notin rotational motion, but they are capable ofoscillating or vibrating about the pointswhich they occupy.

Just as the Rutherford conception of theatom is a kinetic one, the Lewis-Langmuiratom is a static or a stationary one, for in thelatter atom the constituent electrons areconsidered normally to be in a state of rest.

The Lewis-Langrnuir atom is particularlythe chemist's atom, for it accounts verysatisfactorily for the " valency " or combiningpowers of various elements. Nevertheless, itis improbable that the Lewis-Langmuir theorygives us a perfectly true picture of the realatom, since it fails to account for a good dealof observed radiation phenomena associatedwith atoms.

A much simpler type of atom has morerecently been put forward by ErwinSchrodinger, a German. The Schrodingeratom has a nucleus of protons or positively -charged particles of electricity, but, insteadof having the outer electrons revolving aroundthis central nucleus (as in the Rutherfordatom) or vibrating in concentric " shells "or planes (as in the Lewis-Langmuir atcm),the Schrodinger electrons spread out andsurround the nucleus with a sort of " mist "or atmosphere of negative electricity, prettymuch in the same manner as the atmospheresurrounds the surface of our earth.

Just as the earth's atmosphere is densestnear to the surface of our globe, so, accordingto SchrOdinger, the electron " mist " is densestnearest to the proton nucleus of the atom.This density gradually decreases until the-electron " atmosphere ' of the atom tails offinto nothingness.

The Schrodinger atom is the nearestapproach to the ancient idea of atoms, for,according to Erwin Schrodinger, the atomvibrates ,as a whole, the smaller the atom,the greater being its rate of vibration.

This, one of the latest conceptions of theatoms, is by no means a forced notion. Nor,for that matter, can it be considered to befar-fetched, since, despite greater simplicityof construction, the Schrodinger atom to a

Rutherford's hydrogen atom. It consists of acentral positively -charged nucleus having onenegatively -charged electron revolving round it,


234.

large extent fulfils the many exacting demandsof both chemical and physical science.

It is, of course, improbable that, withSchrOdinger's ideas, we have had the lastof the atom theories. It may be that the truesolution of the problem of atom structurewill remain for ever unattainable. On theother hand, a greater degree of elucidationof the problem may come suddenly, and fromsome unexpected direction. Considering thealmost inconceivable minuteness of atoms itis rather a matter for surprise that we knowanything definite about them at all. Thesmallest particle visible to the average humaneye is about a hundredth of an inch in length.Nevertheless, in such a length there couldhe laid in a row, like a line of pennies, nofewer than approximately four millionmedium-sized atoms. Such a fact is

Theoretical diagram illustrating the innermake-up . of air atom of calcium, according to

the Rutherford theory. .


capable of mathematical or, rather, of simplearithmetical demonstration.

rsotopesWith the increasing knowledge of atoms

which was brought about by chemical andphysical science came, some years ago,the discovery that the atoms of any oneelement need not necessarily be all alike.

Take, for example, the gas chlorine. This,for many years, had been known to have anatomic weight of 35.46, which means' thatchlorine is 35.46 times heavier than hydrogen.

By means of certain physico-chemicalsystems of great complexity it was discoveredby Dr. F. W. Ashton, of Cambridge, thatmany chemical elements, such as chlorine,could be separated into two or more com-ponents. Taking the case of chlorine gasas an example, it became apparent that thereexist two chlorines, the first of these havingan atomic weight of 35 and the other possessing -an atomic weight of 37. Both these types ofatoms possess identical chemical properties,but one is heavier than the other.

Such individual types of atoms are calledisotopes. Ordinary chlorine gas having anatomic weight of 35.46 is, in reality, a mixture(in the proportions of 4 to 1) of the lighterand the heavier chlorine isotopes. Normallythe isotopes of chemical elements are insepar-able, and it is only by dint of applying tediousand complicated methcds that a partialseparation of such identical elements ofdifferent atomic weight can be effected.

Elements, such as oxygen, which have noisotopic forms, are nowadays termed " simpleelements." Thdse which, like 'chlorine, arecomposed of atoms of identical chemicalproperties but of different weights are knownas " complex elements." In some instances,as many as six or seven isotopes of the sameelement can exist. Hence the recognised

April, 1943

atomic weight of such an element is neces-sarily merely an average of the atomic weightsof all the isotopes of that element.

Modern notions concerning the structureof atoms, together with the introduction of theconception of chemical isotopes have, to someextent, greatly complicated the picture of theatomic world which is presented to thepresent-day chemical student and inquirer.Yet the age-old theory of the essentially" grained ' or atomic structure of materialthings persists as strongly and as vividly asever in modern science. It is with regardto the make-up of the individual atoms ofmatter that scientific and chemical theoriescontinue to evolVe themselv& The funda-mental principle upon which matter is madeup is as much taken for granted nowadaysas it was thousands of years ago. It is uponthe details of the question that modernchemical philosophers differ.

Schradinger's conception . of the atom asembodying a central positively -charged nucleus

having an electron "mist" surrounding it.

Items of InterestCarpet Sweeper for LawnsMORE than one method has been thought

out with the purpose of keeping lawns,bowling greens, golf courses and other placesfree from litter. An elementary practice iscarried out by means of a stick with a sharppoint. This spears leava and waywardpaper, which are placed in-- a basket. Theprocess obviously is a long and tedious one.

There is on record an appliance composedof , a frame with metal scrapers -and a brushwhich can be adjusted to an angle from theground. The contrivance is drawn by meansof cords, the metal scrapers collecting, and thebrush sweeping up leaves and other litter.

A new invention of this type has a row ofprongs downwardly projecting from a backstrip fitted with a long handle, in combinationwith a lengthy brush also projecting towardsthe ground. The brush has a back stripconnected to the first named back strip.,As a consequence, the brush trails behind therow of prongs, acting with them simul-taneously. The prongs comb the grass andbring the litter- to the surface. They alsodraw out coarse or wiry blades, and thetrailing brush catches and pushes before it theblades and litter, while the prongs are loosen-ing more of the same in front of the brush.

Preferably, the brush is arranged at an.elevation higher than the ends of the prongs.This is effected to enable them to penetratethe carpet of grass, while at the same timethe brush sweeps along the surface.

Making Flint WheelsNOWADAYS, to combat the shortage of

both matches and lighters, many peoplemake their own petrol lighters. No difficulty

is usually experienced until it comes to theflint wheel ; but here the trouble usuallybegins. After several experiments I adoptedthe following method :

A piece of silver steel, or similar t per cent.carbon steel, is turned down to a diameterslightly less than that finally required, therequisite hole is- drilled and the wheels arecarefully parted off to length. My own wheelsare '(in. dia., and *in. thick and are drilled ?,l' in.to take No. 16 s.w.g. A piece of brass rod,or similar material, is now acquired, and aslot is cut in one end as shown in theillustration, slightly wider than the flintwheels. The slot may, be cut by using two

Secional view of jig arrangement for makingflint wheels.

hacksaw blades simultaneously, and finishingwith a ward file. A *in. hole is next drilledthrough as shown. Now the brass rod isgripped in the vice, and the wheel insertedin the slot by a temporary wire spindle, asshown.

Next, a new, or fairly new, well -cutsecond -cut file is laid on the wheel, and,"understeady pressure, is moved to and fro, thepressure being maintained on both strokes.After a few strokes the wheel is cut withwell-defined teeth of better form than thoseproduced by knurling.

For heat treatment, the wheel is threaded-on to a piece of wire and heated to a brightcherry red (760 deg. C.), whence it is quenchedin oil. No tempering is necessary. Specimendimensions are given..for guidance-D. B.

Mechanical HaymakerTN a few weeks we shall be preparing to

make hay while the sun shines, and it isopportune to note that there has recent:ybeen accepted by the British Patent Officean application relating to an improvedhaymaking machine, which is capable ofperforming three different operations. Itspreads cut grass,- turns about the spreadgrass, and afterwards gathers the dried grassto form swaths.

The machine comprises rotatable tinefork carriers mounted on a common axis,and adjustable into three different positions.In two of these positions, the planes ofrotation of the tine fork carriers are oppositelyinclined in relation to the axis, and, in thethird position, elle planes of rotation extendat right angles to the axis.



Victory in the DesertIncidents in the opening phases of the 8th Army's victorious drive across the Libyan desert, when the remnants of

the Geri-nen Panzer divisions were chased arid rounded up by British armoured columns.

Curiously enough the enemy left the electricpower station intact at Appolonis, and it is here

seen (below) being run by native work sr-s.

The remains of a German Mark IV tank after theRoyal Engineers had finished with it, and (on theright) one of the many knockett:out enemy field

guns found by advancing Sth Army troops.

The extent of the defeat, and the enormous destructionof Axis tanks and other equipment were apparent to theBritish troops as they advanced through territory that wasrecently in the hands of the enemy. The illustrationbelow shows a German 88mm. gun found abandoned

near the coast road west of Alamein.

Much of the desert is rocky, and explosives have to be usedbefore the guns can he safely placed. The illustration (left)shows a capper placing afinnonal in a hole for blasting purpose.


236 NE\A/NES PRACTICAL MECHANICS April, 19 43

MASTERS OF MECHANICSNo. 84.-Otto Lilienthal, the Pioneer of Glider Construction

OTTO LILIENTHAL has been called" The Father of the Aeroplane."Whether he is legitimately entitled to

such historic priority is a matter which is opento discussion, since Lilienthal himself neveractually flew in a power -propelled aircraft.Nevertheless, this individual was certainly theaviation pioneer who, perhaps more thananyone else, paved the way for the firstpower -driven flights, because it was uponprinciples enunciated by him that the pioneer

Lilienthal with one of his early air-fr

mechanically -propelled 'planes were designed.Because Lilienthal never succeeded in flying

a power -driven atroplane, his memory has-suffered an unjustifiable degree of eclipse.But no greater enthusiast in the cause ofhuman flight ever existed than the German,Otto Lilienthal. He was a man who spentpractically the whole of his life in fundamentalresearch into the question of aerial flight, and,had it not been for an unfortunate, and apurely chance, accident, to which hesuccumbed, it seems highly probable thathe would have successfully made the firsthuman flight in a mechanically -driven aero-plane several years before this feat was actuallyaccomplished by the famous Wright brothersacross the sand dunes at Kitty Hawk,California, on that memorable December 17th,1903.

Otto Lilienthal was born on May 24th,1848, at Anclam, Pomerania. From his earlyboyhood he seems to have been fascinated bythe then unsolved problems of human. flight.His brother, Gustav Lilienthal, harboured asimilar enthusiasm, and, while still at school,the two lads built for themselves a set offabric wings, which they fastened to theirarms, and by means of which they attemptedto glide through the air after running down asteep incline. These wings were based upon anearlier design formulated by an experimenternamed Besnier, who lived in the sixteenthcentury. They were, of course, completelyunsuccessful.

Franco-Prussian WarIn 1864, Otto Lilienthal entered the

Potsdam Technical School to be trained as anengineer. From that institution he proceededto the Berlin Technical Academy. He was inhis third year at that college when theFranco-Prussian War of 1870 broke out.Otto Lilienthal volunteered for service, andtook part in the siege of Paris.

After the conflict had ended victoriouslyfor Germany, Lilienthal obtained a numberof posts in various engineering shops in

awes.

Berlin. Finally, in or about 188o, he set up a,machine shop of his own, and specialised inlight precision engineering. He evolved aparticularly compact form of lightweight steamengine, and he invented a type of marinesignal which brought him, as a reward, theofficial Silver Medal of the State.

After the Franco-Prussian conflict of 1870Gustav Lilienthal appears to have lost allpractical interest in the solution of humanflight. At all events, he relinquished all

experiments, so that it wasentirely alone, and practicallyunaided, that the more enter-prising brother, Otto Lilienthal,embarked upon a course ofspare -time studie, which, atthat time, centred chieflyaround the close and scientificobservation of bird flight.Gradually, and with almostinfinite patience, Otto Lilienthalgarnered information relatingto the behaviour of birds inthe air. He noted theirautomatic responses to ever-changing air -resistances, andparticularly did he study, bymeans of their observation,the properties of wing -likesurfaces in relation to aircurrents.

Almost from his boyhooddays he seemed intuitively to

have realised that the solution of theproblem of human flight must come mainlyfrom a scientific investigation of the mostfundamental aspect of the question, to wit,

Otto Lilienthal making a landing with- his- biplane glider.

that of the design of the air -frame whichwas to be made to -travel through the air.He did not, as others before him had done,endeavour to fit an engine into an air -frame,and then proceed to find out what mighthappen in practice. Onthe contrary, OttoLilienthal concentratedupon evolving a practic-able type of air -frame,which, after it had beenthoroughly tested out andpassed- as satisfactory,could then have a powerunit incorporated into it.

The Flight of BirdsIn 1889, Lilienthal

published the results ofhis observations of birdflight in a pamphlet eti=titled " The Flight ofBirds as a Basis for theArt of Flying." Thepamphlet was an historicone. It constituted the

first really scientific onslaught on the problemof human flight after centuries of mereimaginings on the part of various would-beaeronauts.

He experimented with the lifting powersof various types of plane surfaces, and he madethe fundamental discovery that the lift givenby a curved or cambered surface isconsiderably greater than that produced by aperfectly plane surface.

In 189o, Lilienthal finished with hispreliminary theorising. He got down topractical work, and in the following year(1891) he successfully completed his firstscientific glider. The framework of thisdevice was, composed of willow rods whichwere covered With stout cotton fabric. Thetotal wing surface of the craft was about

oosq. ft .Lilienthal fastened the glider to himself by

dint of pushing his forearms through paddedtubes and by clinging tightly to a woodencross -bar. In this manner he transportedhimself through the air with the glider abovehis shoulder -level and with his legs danglingmore or less perpendicularly below him.

At first he got into the air by jumping off astrong spring -board placed at the top of anincline. Some months later he, began to makeuse of convenient hills, and, finally, in 1892,he had constructed near Berlin an artificialhill or conically -shaped eminence somesoft. in height, which was thrown up withearth and rubble dug out from the bed of anearby canal.

The first scientific glider flights met. withimmediate success. Lilienthal was rewardedfor his years Of patient study of fundamentalflight principles by finding that his gliderbehaved quite reasonably in the air, and thatit showed all the characteristics of air-worthiness which he had expected.

After a few initial trials, Lilienth4al foundhimself readily able to traverse distances of ahundred yards under good wind conditions.Thenceforward, his aim became that ofendeavouring to improve the stability of hismachine. This he effected, at first, by movinghis body backwards and forwards or toand fro whilst in the act of gliding. Suchactions, according to Lilienthal, rapidlybecame instinctive ones on the part of aglider pilot, and were similar to the instinctivebalance of a bicycle rider.

Enter the BiplaneBy changing the centre of gravity of his

gliders as a result of the alteration of bodyposition whilst in the air, Lilienthal found

Lilienthal aboUt to commence a glide from the summit of hisartificial hill near Berlin. (1895.)



that he could to some extent make the glidersteerable. Then, in order to extend the rangeof his glides, Lilienthal discovered that hewanted a greater lifting surface. This heattempted to effect. by increasing the area ofhis glider wings, but it quickly becameapparent to him that there existed a very rigidlimit to which this extension could be taken.Therefore, he hit upon the idea of havingtwo relatively small planes, the one situatedabove the other-thereby introducing in apracticable form our present-day principle ofthe biplane.

Says Lilienthal, referring to his " biplane "flights :-

" The flights undertaken with suchdouble -sailing surfaces are remarkable fortheir great heights. I often reach positionsin the air which are much higher than mystarting -point. At the climax of such a lineof flight I sometimes come to a standstill,so that .I am enabled while floating to speakto the gentlemen who wish to photographme regarding the best position for the

' photographing. At such times I feelplainly that I would remain floating if Ileaned a little to one side, described acircle and proceeded with the wind."With increasing experience of glider flights,

Lilienthal perceived that the motions of apilot's legs or body were not sufficient tostabilise the glider to the extent which itrequired for relative safety. Something extrawasoiecessary, some additional control planewhich could be operated 'by the pilot in orderto bring the glider back to normal positionafter it had encountered a sudden gust ofwind.

The Tail of the AeroplaneFor the purpose of effecting this require-

ment, Lilienthal devised a couple of smallerplanes which he affixed by stays to the rearof his machine. Thus came into existencethe " tail " of the future aeroplane.

At first, Lilienthal controlled these rearplanes by means of movements of his head,but, later, the controls were operated by thearm movements of the pilot.

It was Lilienthal's avowed intention toproceed with the design and construction ofa power -propelled glider immediately afterhe had satisfied himself as to the practicalairworthiness of his ordinary gliders. The

petrol engine at that time was'not sufficientlydeveloped to be applied to aircraft powering.The steam engine, despite the ideas andassertions of other inventors, was, inLilienthal's opinion, an impossibility foraerial power flights. What he intended totry out was a form of " carbonic acid motor,"that is to say, a motor actuated by gasexpansion, the working " gas being carbondioxide (carbonic acid gas) contained in aliquefied condition in a. small, lightweightsteel cylinder.

Alas, however, Lilienthal never got to this

A modern glider inflight, just afterbeing launched.Note the team inthe foreground with

the towing rope.

stage of his programme, although he madeactive preparations for it. He actuallyconstructed a large glider which, at a laterdate, he intended to " power " and thus torealise mechanical flight, but for some reasonor other he became dissatisfied with thesteerability of the machine. The glider wasstabilised by means of a light form of tailplaneworked by the pilot's head, and it was onAugust 9th, 1896, whilst testing this machine,that Lilienthal apparently became confused inhis movements in the air, as a result of whichhe crashed heavily from a height of soft.He sustained a fractured spine and othersevere injuries from which he died the nextday in a Berlin hospital. Many people calledhim a madman, but in reality he was one ofScience's martyrs.

Two Thousand TrialiAll told,'Otto Lilienthal made considerably

more than 2,000 successful glider, flights, the

greater number of which took place from hisown artificially -constructed " hill " nearBerlin. If he could have conducted hisexperiments secretly in a back room, hewould have done s9., but of necessityLilienthal's laboratory comprised his soft.conical hill or eminence outside Berlin,together with the air surrounding it, a testing -ground which was open to the observationsof all comers.

Lilienthal had a kindred enthusiast inEngland, one Percy Pilcher, who carriedout his experiments until he, too, met his

death in a similar manner. As a result ofLilienthal's trials (and also of Pilcher's) itbecame difficult for thinking people to scoffat the possibility of mechanical flight, sincethese pioneer glider' trials proved so con-clusively the practicability of sustaining aheavier-than-air machine in motion in theatmosphere.

Otto Lilienthal, in fact, ushered in the eraOf controlled human flight. He reducedgliding flight to regular practice. And it isnoteworthy that no less than seven yearsafter his death Wilbur and Orville Wright,the first men to fly under mechanical power,acknowledged that they had closely followedLilienthal's designs and principles in theconstruction of their aeroplane and thatthey had duly profited by his work.

Indeed, not merely the brothers Wright,but many other early airmen owed a debtto Lilienthal, which in some instances theyhardly troubled to acknowledge.

Gliders' leave the ground before their towing 'plane, and' here, at the U.S. Army Air Forces' Glider School at Elmira, New York, they areclear of the ground, riding higher than the 'plime.- They take -off after a run of about Soo feet while a tow -plane needs a,run of

about Imo feet. In flight the gliders remain slightly above the level of the tow -plane, with nose a little down to maintain lift.

46-



Figs. 22 to 24.-Principle of the clown on,ladder toy.

Toy See -sawsEVERY reader will have seen the see -saw

novelty illustrated in Figs: 20 and 21.In this toy, which is merely symbolical

of many variations, the action imparted byan inclined plane is allied to that of a rotatingspindle to which the figures are attached.For example, in Fig. 20 is indicated a rodcarrying two acrobats, and also a centralspindle on which the arm and figures areaccurately balanced. By depressing one ofthe figures the arm will steady itself for afraction of time, and then, as the arm tendsto return to equilibrium, the spindle willslide down the incline plane. These revolutionsare repeated until the spindle reaches thebottom. Fig. 21 is an adaptation of the sameidea. Here an upright having arched sidesis engaged by two pins in.the arm of the see-saw. Each arc is described from the point ofintersection of two arcs on the opposite side.The arm is, of course, provided with suitablestraddle pieces to pass over the uprightstandard.

Fig. 20,-In this toy the see -saw actionimparted by inclined planes is allied to that ofa rotating spindle to which the figures are

attached.

The Ladder and Clown ToyIt is not -known when the toy illustrated

in Fig. 22 was first produced. It is certainlyover a century old. It will be seen that aclown is attached to a rectangular block ofwood, having slots cut in it, as shown in Figs.23 and 24. It will be understood that therungs of the ladder must be of such a sectionthat they easily slide into the slots, and thedistance between rungs needs to be carefullygauged. It will be noticed that the slotshave a circular hole at each end, and the

Toy Manufacture:rungs should be made of such a width thatthey will turn easily in these holes. When theclown is placed on one of the rungs it willtumble in a series of somersaults; one rung ata time, until it reaches the_ bottom of theladder. Practical instruction on a typicalladder toy is given later.

Novelty Money -box. The figure of a clown is a popular figure

to employ in working toys. The money -boxshown by Fig. 25 has a clown suspended on a

Further Methods of Operation,

(Continued from page 199,

man continuously raising the bottle to hismouth.

Quite a number of such novelties canrapidly be devised. For example, the birdin the cage (Fig. 28). A more rapid and

Fig. 2 k.-An adaptation of the same ideashown in Fig. 20. Here an upright having

arched. sides is used.

swinging pivot. Above the point of suspensionis a pocket sufficiently large to accommodatehalf a crown. When a coin is placed in thispocket, the clown will capsize, and the- coindrop into the box below, the clown thenreturning to normal position.

Simple Moving Picture DevicesUnder various names, such as metamorphosis,

zoetrope, and thaumatrope, a number of

Fig. 27.-How to lay out the novelty shown in Fig. 26.

interesting novelties, which really wereprecursors of the modern cinematograph, havebeen produced. Figs. 26 .to 3o show thesimplest of these. Here the figure of a man isshown to be drinking outof a bottle ; a circulardisc of card has on oneside the picture of a man,and on the other the armcarrying the bottle. Astring is attached to eachside of the card; and whentwirled between the fingersthe card will rotate andgive the illusion of the

Fig. 26.: --An optical illusion, toy.

Is t0

Fig. 25.-The figure on themoney -box will deposit a coin

in the money -box beneath.

realistic action can be imparted by connectinga loop of elastic to the card and connectingthe string to the elastic. The zoetrope orthaumatrope is clearly indicated in Figs. 29and 3o, showing two forms. Here a series offigures illustrating progressive movementsare drawn at regular intervals on the inside ofa slotted and open-ended cylinder, mountedon a suitable base in such a way that thecylinder can be spun. By sighting throughthe slots the sequence of movements willappear to be continuous; thus a dog can beshown as chasing a hare, and so on by thismeans. a

The Simple BuzzerFigs. 31 and 32 show the simple buzzer.

This consists of a disc of tin with two holesin centre, through which a loop of string ispassed. Upon twisting the string and alter-nately pulling on the string and releasingthe pull on it, the buzzer will continue tospin indefinitely. An improvement on thisidea is shown in Fig. 32, where three cardsare connected to a fourth and larger disc.When this is spun in the same manner as

28.-The "bird -cage'.!optical illusion toy.

Fig. 29.-One form -ofthaumatrope or zoetrope.



Principles and Practiceand Constructional Details

March issue)

the buzzer a very puzzling spinning effectresults.

A MetamorphosisA little idea which works on the same

principle as the zoetrope' and the thauma-trope already referred to, is illustrated in Fig..33. Here a series of pages, each containingan illustration, slightly differing, but forminga successive series, are rapidly released from

Fig. 30.-Another form of thaumatrope.

contact with the thumb. By persistence ofvision the pictures will appear to be moving.

Glass Bowl IllusionsWe have all seen the two bands .of tin

mounted on an Archimedean screw, which

Fig. 37.-A novel rocking motion device inwhich the horse travels forward and appears

to vault.

are rotated by a bobbin, giving the illusion ofmonster bubbles. These are illustrated inFig. 34, while Fig. 35 shows an elaborationof the idea where a small goldfish is added togive -the illusion of a fish swimming in a bowl.

Rocking Motion NoveltiesQuite a number of these devices can

be devised by following the schemes indicatedin Figs. 36 to 42. In Fig. 36 it will be seenthat the grotesque animal has spindles passedthrough its fore and hind legs, and these

spindles are mounted eccentrically in thewheels. When the toy is pushed along, theanimal will appear to be galloping. Fig. 37shows an improvement on the toy rocking -horse idea. A horse is mounted on a littlecarriage running on a rocking track ; thehorse is thus capable of the dual motions ofrocking, and, apparently, galloping forward.Fig. 38 is a development of this idea. Bypushing on the back of the device the horseis made to appear to gallop. In Figs. 39 and

Fig. 3i-A more complicated application ofthe buzzer principle in which three or more

discs are used.

40 is shown, in two positions, a jockey mountedon a racehorse. It will be seen that thelegs are mounted on wire cranks. By pullingthe cord attached to the jockey's head, actionis imparted to the figure. Figs. 41 and 42show the elements of the galloping ass.The hindquartersof the animal arehinged and theaction of pulling onthe cord attached tothe hat supplies themotion.

One system of bmaking a walkingdoll is shown inFig. 43, where aseries of -feet aremounted concen-trically round apivoted drumsecreted inside theskirt of the doll.When the doll ispushed along bymeans of thehandle, the actionof walking is wellsimulated. Typical walking toys operated bymeans of inclined planes are described later.

Fig. 33.-A metamorphosis. In this device aseries of related movements are drawn on eachleaf of the book, and when these are flickedrapidly past the fiver, continuous or " moving "

pictures are obtained.

Fig. 38.-A development of the idea sketchedin Fig. 37.

examples of toys having cranked axles ; thecrank is Usually connected to some part orparts of the figure so that when the toy is

Walking Figures Fig. 31.-A simple Whistlinguzzer. Motion is imparted by

twirling the two strings.

Fig. 36.-A leapingdog novelty. Thespindles pass throughthe wheels eccentrically.

Cranked Wheel ToysFigs. 44 and 45 are typical

Fr:zs. 39 ,and 40.-By pulling on the cord passed through a wire st3ple in theicckey's head, a galloping motion is given to the horse.

Fig. 34.- ' Bubbles"are formed when theloops are spun bymeans of the Archi-

ntedean bobbin.

Fig. 35.-` Thefish -in -bowl"novelty. Hene per-sistence of vision,when the ring isrevolved, provides.the illusion of a fishswimming in a bowl

of water.

pulled along, motion is imparted to it. Thisidea lends itself to infinite variations.

Figs. 41 and 42.-The galloping ass, the hindquartefs ofwhich are hinged. The action of pulling on the corl

attached to the 'hat supplies the notion.


240

Fig. 43.-A simple ideci formaking a walking doll. Whenthe doll is pushed along by meansof the handle, the action of

walking is imitated.


Fig. 44.-A ,typicalexample of acranked -axle toy.

The Use of Springs in Soft ToysSome attractive soft toys can be made by

substituting for the usual rigid jointed armsand legs spiral springs of the form indicatedin Fig. 46. Piano wire should be used for thesprings, because this provides the maximumamount of springiness, and will return toform after being stretched or distorted.

Fig. 46.-Soft toys can be improvedby substituting spiral springs for the

rigid -jointed arms and legs.

Eye Movements for Soft ToysThose readers who wish to make soft toys,

such as dolls and teddy -beaks, which closetheir eyes, should suspend small lead weightsto the eyes themselves, as shown in Fig. 47.,It will he obvious that when the doll is in arecumbent position the effect of the weightwill partly rotate the eye (suspended onsuitable pivots) ; the eyelid is, of course,fixed to that part of the eye which is normallyout of sight. Fig. 48 is a further detail of thescheme.

Squeaking ToysThe usual method adopted with

dolls and squeaking animals isshown in Figs. 49 and 5o. It

Fig. 5r.-The acrobats.

crying

Fig. 4.5. -This toy is similar toFig. 44. The bear is pushedbackwards and forwards by the

cranked axTh.

will be seen that small bellows placed insidethe toy have a lead weight attached to anarm. When the doll or toy is held upright theweight will naturally hang vertically, but whenthe toy is placed in a recumbent position thelead weight will collapse the bellows, thusforcing the air in it out through a smallopening, in the mouth of which is a whistle -like device which emits the squeak.

Sand -operated ToysA very popufar model is that in which an

acrobat performs upon a trapeze (see Fig. 51),but there is a scopefor ingenuity in de-vising other modelsfor which are giventwo suggestions,namely, the water -mill and the man atthe grindstime (seeFig. 52).

The MechanismFigs. 47 and 48.-Dolls' eyes can The mechanism isbe made to open and shut by very simple, as will

weighting them with lead. be seen from Fig. 53.A neatly fashioned

box of thin wood is the first essential. It maymeasure t2in. x 9in., with a depth Of

A sheet of glass will be required to close inthe front. This may be secured at the edgeswith passe-partout strip. Vrhen finished, thewhole thing must be sand -tight.

Fig. 54 shows the box" in sectional view.A narrow fillet is fixed round the inside, atabout the middle of its depth, to carry thesheet.of stout card on which the backgroundis painted, and in which the forward pivot ofthe wheel works.

The Sand ReservoirReferring to Fig. 53 it will be seen that the

sand reservoir is madefrom a strip of card -

Fig. 53. - Thesand reservoir.

Fig. 54.-Asectional viewof the box forholding the

sand.

Fig. 55.-The sand wheel.

April, 1943

board, and that this strip is continued down-wards to make the channel through which thereservoir is refilled when empty by turningthe box round anti -clockwise. This piece ofcard rhust have a width exactly equal to thatof the space between the back of the box andthe cardboard background, so that when thelatter is glued in place, a glue .joint may bemade also between it and the reservoir.

A small hole must be made in the centre ofthe angle that forms the bottom of thereservoir to allow of a fine stream of sand tofall upon the wheel.

After piercing, the hole should be madeclean with a hot wire, or it may have fitted init a short length of small diameter brasstube.

The Sand -wheelFig. 55 shows how the wheel is constructed

from cardboard. The left-hand view is as itwould appear with one face removed. In thecentre is a wooden disc to afford a goodfixing for the wire shaft.

The right-hand view shows the bearingsand the collars on the shaft to prevent lateral

Fig. 49.-Squeaking toys can bemade by placing a small bellows

weighted with lead inside them.

Fig. 50.-Details of, the bellowssqueaking dolls.

placed inside

movement. A small brass plate is let into thewooden back, drilled to take the end of theshaft.

A small amount of lateral play may be allowedto guard against jamming. As to the figures,these should be copied on to stout Bristolboard and cut out neatly. They may then becoloured to taste.

The FiguresThe acrobat, used in Fig. 5x, is shown

in Fig. 56, and it consists of five pieces

Fig. 52.-The grindstone and (right) the water -wheel.


April, 1943

-the trunk and four limbs. The joints aremade with sewing cotton knotted on eachside. As the hands have to be separated, ashort tube should be made by rolling pastedpaper around a piece of the same wire as thatused for the shaft. This tube may be lin. long.After the figure has been jointed, insert thetube between the hands, pass a wire throughthem and tube, glue the ends of the tube, andforce all together. When dry the wire may beremoved. When mounted on its shaft therewill be sufficient friction to hold the figuresecurely to it.

For the stationary figure the same outlinemay be used, but reversed, rearranging thearms and legs. When drawn as it has toappear, the figure may be cut out in one piece.It should be fixed with small wooden blocks,so as to stand about midway between thebackground and the glass.

A round notch (see A, Fig. 56) should becut in the instep of one foot of the movablefigure. This hitches on to the trapeze fromtime to time, and varies the figure's revolu-tions.

The man (Fig. 57) also should consist offive separate pieces-the trunk, the right arm,

NEWNES PRACTICAL MECHANICS 241

the left arm (in two pieces), and the two legs(in one piece), the joint being at the hips.

The right hand connects with the crank

0Fig. 56 (left).-The Acro-

bat:

Fig. 57.-How to makethe figure forthe Grind-stone Model.

of the 'grindstone, and the left hand is fixedat a point where a tool would be held. Inthis case the shaft must be long enough toadmit of its fore end being bent to form thegrindstone crank handle. The man's feetmay have a strip of ground attached, as shown

in Fig. 52. The running of the sand wheelmust be tested, in all cases, before the back-ground is glued in place, as, unless quitefree, it may jam with a grain of sand.

The Water -wheel and GrindstoneThe water -wheel, which, it should be noted,

is undershot, and the grindstone mustboth rotate clockwise, so that in arranging theinternal mechanism the sand -wheel must beset more to the left than shown in Fig. 53, toallow the stream of sand to impinge on itsright-hand side.

Build up the water -wheel from cardboardwith floats complete, and set forward thatpart of the foreground that comes in front ofit, to allow the necessary space for the wheel.Before closing in, fill, the reservoir with cleansilver sand that has been passed through finewire gauze or muslin to exclude all largeparticles.

If the outside of the box be covered withRexine, the material may be brought forwardat the front and turned over to secure theglass.

(To be continued.)

Sidel on SearchlzNotes

T0 -DAY everyone accepts searchlights asa matter of everyday (or should it beevery -night ?) fact, but few realise

that they may be used for other purposesthan the spotting of enemy aircraft andassisting the ' defence guns by illuminatingtheir targets. They may have watched onesearchlight " pass on " a raider to another andanother as the aircraft progresses from onearea to another-but have they wondered whyan aircraft always appears white in thebeam?

Colouring for Night -flying AircraftSeveral years ago- extensive experiments

were carried out with a view to finding theoptimum colouring for operational night -fly-ing aircraft. It was readily appreciated thata light coloured 'plane- all military aircraftof that period were of aluminium colour-might well show up to disadvantage, andfinally dark green was chosen as the best tonefor practical invisibility for night flying.Thus the night bombers of that period-theHeyfords, Virginias, Faireys, etc.-were allcoloured dark green. The British nationalmarkings, red, white and blue roundels,were modified and the white ring omitted,a practice which has continued to this day,

on the. Many Purposes forwhich They mayBy A. M. COLBRIDGE

but is not general for all positions on theaircraft.

It would appear at first that jet black wouldbe the ideal colour for night -flying aircraft, butit was generally found .that, whatever thecolour, an 'object in a searchlight beamalways showed up' white. This is merelybecause the image seen is simply reflectedlight from the searchlight itself. The beam,being of terrific intensity, completely blotsout any colour of the object and reveals thewhole as white:

Non-reflecting PigmentA year or two ago certain reports appeared

in the American technical press throwing aninteresting sidelight on , this probleni. Acertain firm specialising in the provduction ofpaints and dopes were credited with havingfound a perfect non -reflection pigment dopeof cellulose base, and that it had been employedon night -flying aircraft in this country. Ifall the properties claimed for it were true itwould mean that a 'plane so painted would be'almost invisible, even if caught in a searchlightbeam. This paint would reflect no light andtherefore there would be no object in thebeam except, possibly, a darkish patch of. indistinguishable form.

be Used

his

Some confirmation of this was forthcomingfrom a German source, although rather -unreliable, which reported that a portion ofa crashed British aircraft so painted had beentested by holding it in the beam of powerfulcar headlamps. At a distance of about15 metres the painted surface was practicallyinvisible.

This leads to interesting speculation, butin the absence of further confirmation orcomment such reports should be treated withreserve.

Finding Heights of CloudsApart froni the obvious duty of " illuminat-

ing" hostile aircraft as mentioned above, asearchlight may also be employed on cloudynights to find the height of the cloud base(see illustration on the following p. ge).

The searchlight is set to shine verticallyupwards and where the beam strikes the clouda spot of light is seen on its base. if now froma measured distance from the base of thesearchlight a reading is taken of the anglebetween the horizontal and line of visibilityof the spot of light the cloud baseheight maybe quickly computed. The base length, 1,should- not be too great, otherwise the anglemeasured will he small and the liability to

How a searchlight beam appears bent when projected at a narrow angle to the grout:,:'.



SE4kCI-fhti51.1

EL ANGLE

ATOkiND LEVEL

6.

Method of finding the -height of clouds by means of a searchlight.

error greater ; similarly, if the base length is'short the measured angle is large and, again,errors in reading will be introduced.

If the measured distance betsireen theobserver and the base of the searchlight is,say, /ft., and a is the angle measured by theobserver, then the height of the cloud base infeet is given simply by the following equation :

Height of cloud base =I tan a.

Optical IllusionsThe following phenomena, in the nature

of optical illusions, associated with searchlightsmay also prove of interest. On a moonlightnight an aeroplane flying overhead may beclearly visible to a ground observer, butshould a searchlight in the near neighbourhoodbe switched on (away from the aircraft), theaeroplane, before so clearly seen by the nakedeye, now disappears ! The solution of this phenomena is similar to that explaining whyit is quite possible to see out of a room withmuslin or net curtains, but quite impossibleto see in during the day. It is a question ofdegree of lightness-the added brightness ofthe sun shining on the outside of the curtains,or the sudden switching on of the searchlight,reduces the effectiveness of the image (or,rather, its response to the retina), and thus itis impossible to see through the curtain fromthe outside, or the original image of theaeroplane disappears. It is, of course, stillthere, but dimmed below that intensitysuitable for perception.

Bent " Searchlight BeamThen, again, there is the case of the

" bent " searchlight beam! When a Oarch-light beam is near horizontal, i.e., nearlyparallel to the horizon, the /* Odle part oftenappears higher Man the two eild4, or, in otherwords, the beam appears to be arched orbent. This is a pure optical illusion, and duemainly to the fact that there is no backgroundto line it up with. If this is done, such as byholding a walking stick parallel to the beam,the illusion disappears.

Why is a searchlight beam visible at all ?Well, this is simply because the light generatedat the source is reflected off the numerousparticles of dust and droplets of water presentin the atmosphere. It has been said that theintensity of the beam could be .used tomeasure the degree of purity of the air, leadingto the assumption that searchlights in industrialareas would normally appear brighter thanthose in country areas on dry nights.

The persistency of a searchlight beam isanother interesting phenomenon. When a

beam is shut off the image persists in ourminds for a second or so after. This is partlyexplained by the fact that the carbons of thearc do not " die " immediately, but the effectis heightened by one's own imagination.

Shadows and FogLight has many peculiar properties and

can play many tricks with the imagination.In foggy weather some particularly amazingphenomena are possible. Shadows may be caston to the fog, usually very large and distortedin shape, when a solid object is interposedbetween the source of light and the fog,bank.In some cases these shadows may have depth,due to uneven formation of fog banks. Insimilar manner a searchlight may cast ashadow of an aeroplane in its beam on to acloud above, although this is generally moreclearly defined.

Possibly many readers have been to acinema on a foggy hight. The fog filters intothe body of the cinema itself and the projector,transmitting light to the screen in the form ofa divergent beam which casts queer shapeson the fog belt. Each little particle of fogreflects light in all directions, lighting up theinterior of the cinema and dimming the finalimage on the screen as if the fog itself was

Showing how a beam oflight throws an enlargedshadow of an object on afog bank. The shadowmay have depth due to theuneven.formation of the fog

bank.

not a sufficient hindrance to vision ! Thefinal image is dimmed still more by comparisonwith the relative brightness of the wholeinterior.

Coloured Searchlight BeamsReturning once more to searchlights. It

has been found possible to transmit beams oflight through cloud and fog to a certain extent.The Germans, in particular, have for sometime employed beams of coloured light,obtained by the use of red, blue, orange, yellowand green filters. Possibly these colouredbeams have a greater penetrating power shallwhite light, but, judging from the variety ofthe colours employed, the final solution is farfrom reached. It does not necessarily followthat the ground observer will be able to seebeyond the cloud, even if the searchlight doespenetrate it, but there is quite a possiblilitythat he will be able to do so. It actuallydepends upon a number of rather complexfactors, but with further experimental worksuch a condition may be established in thefuture.

To be caught in a searchlight beam is arather terrifying experience for theinexperienced aircrew, particularly the pilot,for the whole of the interior of the aircraft islit up and the surrounding sky appearsperfectly black by comparison (a case of lightintensities, again). This effect is obviouslythe more pronounced the nearer the objectto the source of light, but even at relativelygreat heights such conditions can be somewhatdisconcerting.

Evading the SearchlightsSearchlight evasion is quite an art-the

advantage lying with the searchlight in thatit is able to sweep a whole arc of the sky in amatter of seconds, and thus, in this sense, ismore manoeuvrable. The smallness of theobject and the presence of cloud are thepilot's weapons.

Above a certain height, however a search-light is relatively ineffective, and thus high-flying aircraft are fairly safe from theirsphere of action. The maximum effectiveheight is not known, and will vary accordingto the type of searchlight and the variousimprovements introduced, but it may be takenat is,000 feet. Thus, to avoid contact thehostile aircraft would fly above this height,but the searchlight can claim a " half victory "in that it has forced the raider to fly high fromwhere precision bombing is very difficult, if notimpossible, except in conditions of exceptionalvisibility.


April,. 1943 NEWNES PRACTICAL MECHANICS 243

Types of British AircraftAn Artist's Impressions of Some of Britain's Fighters and Bombers WhichAre Very Much in Present` -day News

Avro Lancaster I, a four-en,gmedbomber. Underslung Merlinengines four in line: underslung,and projecting well out, with highbosses. Twin outriffed fins andrudders. 'Span 102 feet, length69 feet ,4 inches. The under-carriage is backwards retracting

into inboard nacelles.

. Handley -Page HalifaxII. Tour Merlinengines. Twin bump

nose.

Bristol Beaufighter II. Two Herculesengines. Low short stub nose, and

curve -pointed fin and rudder.

Short Stirlin, I. Four radial Hercules eneincs

Hawker Hurricane ..11c. - Merlin engine.Humped back ; -radiator under centresection. May be seen with external fueltanks, or bombs, Other Marks have ,no

cannon.

Westland Whirlwind 1, a twin-eng,ined fighter. Peregrine engines.Tail and garrow fin and rudder.

Tailplane set very high.

-



Overhauling a Lawn Mower

Rotary Blades

0,111)10»»)»)»)»

,)»»»))))tipopmpo

\Roller4.-Rear view of a side -wheel mower showing

the rotary blades and roller.

AFTER being stowed away during thewinter months a lawn mower usually.requires overhauling and cleaning

before it is used again. The cutting bladesand under -plate may have become rusted,especially if these parts were not well greasedwhen the mower was put away at the end ofthe autumn. -

One method of removing the rust is to wellsoak a piece of rag in paraffin, place it on the

Fig. 1.-Part of one of the side frames showing the fixedcutting plate and adjusting screws.

rusty parts, and leave for a few hours. Thenwell rub the parts with the rag, which shouldbe sufficient to remove the rust, but if anystill remains, rub the affected parts withfine emery paper. After this, wipe over theparts with an oily,rag.

Cleaning the PartsIf the internal working parts of the mower

have not been cleaned for a season or two,the mower should be partly dismantled byremoving one of the side wheels, as in Fig. 2.The internal teeth of the wheel will probablybe clogged with small grass cuttings, and fineearth, which should be removed with the aidof a pointed implement, such as a long nail.After clearing out all the sediment frombetween the teeth, brush out the spaces witha stiff brush.

Next, remove the ratchet -pinion, D, andwell clean this inside and out. Remove thesliding ratchet pawl from the shaft, and aftercleaning this, replace it, and give a liberalapplication of thick machine oil. Also welllubricate the inside of the ratchet -pinionand side wheel before replacing them. Treatthe other side wheel and internal parts in thesame way.

Cleaning and Maintenance

By "HANDYMAN"

Adjustment of Under -plateIn order to get the best results

from a mower the rotary cuttingblades must be properly fixed inrelation to the under -plate, which

C must be adjusted so that it barelytouches the blades the whole wayalong its length. If set too tightly,the machine will run heavily, andcause unnecessary wear on thecutting blades.

If the sides of a mower areexamined it will be found that theunder -plate is attached to a cast-iron member which is carried intrunnion bearings, and that thewhole unit can be tilted by meansof two screws (see Fig. t). Byadjusting these screws carefullythe under -plate can be reset in

relation to the cutting blades. If it isfound necessary to bring the cutting edgeof the under -plate slightly nearer to therotary blades, slacken screw A on eachside very slightly, and screw down screw Bhard (on both sides). When adjusted cor-rectly, the cutting blades should spin freely.

Sharpening the Cutting BladesAfter a mower has been in use for two or

more seasons it will generallybe found that the cutting edgesof the rotary blades and under -plate have become blunted, andwill require resharpening. Thebest method is, of course, tohave this work done by thelocal ironmongers' stores. Agood makeshift method is touse one of the small sharpeningtools which can be purchasedat most hardware stores. Thistool simply consists of a pieceof carborundum stone mountedin a wooden holder, and in useit is placed over the edge of acutting blade and worked toand fro, applying pressure allthe time. It is rather a tiringjob to treat all the cutting edgesof the blades in this way; but

with a little patience the cutting qualities ofthe mower can be considerably improvedby this method.

Another method for resharpening, or re-_grinding the cutting edges of the blades isknown as lap-ping, .using apaste of fineemery powderand oil. Firstremove the sidewheels by takingout the splitpins, and thenremove the smallratchet sprocket -wheels, changethe right-handone over to theleft-hand side,and vice versa,and then replacethe side wheels.The blades willnow revolve in pfthe reverse direc- '411(14(tion, as indicatedin Fig. 3. Smear

some of the paste along the top of theunder -plate, as at E, and then adjuSt theunder -plate so that the blades scrape overthe surface as they revolve.

If the machine is now pushed about, theblades in rubbing over -the under -plate withthe emery paste between will be reground toa correct cutting edge again. When. the'blades appear to have been lapped sufficiently,return the sprockets to their correct sides,

N

Fig. 3.-Illustrating a method of " lapping"the rotary blades.

and. wipe off any remaining emery paste.After well oiling the mower will be readyfor use again.

Adjustment of Rear RollerThe purpose of the rear roller (see Fig. 4)

is to regulate the height of the grass cut.When the roller is raised to its fullest extenta close cut will be obtained, but for cuttinglong grass the roller should be lowered as faras possible. The position of the roller isadjusted by loosening the nuts and bolts,C, C, on the side frames.

MaintenanceA mower, like -any other machine, requires

proper attention if it is to give efficient service.It is important that all the working parts,including the ahie bearings of the side wheels,the bearings of the rotary cylinder, and thefront roller axle, are frequently oiled; atleast once every time the mower is used.

Before oiling, make sure that the oil -holesare not clogged with earth and small piecesof grass cuttings. It is a good plan to clearout the oil -holes occasionally with a pieceof pointed iron wire.

Carefully examine the surface of a lawnbefore mowing, and remove stones, twigs, orany other similar objects, as these are liable todamage the cutting edges of the rotary blades.Any loose soil, such as worm casts, should beraked flat, and rolled before mowing a lawn,as the grit contained in the earth tends toblunt the cutting edges.

Finally, check over all nuts and b-olts witha spanner to ensure that they are properlytightened up.

Fig. 2. -Side view of part of Mower with side wheelremoved.


411111k.


THE WORLD OF MODELSBy "MOTH US"

A skilled craftsman 7., arl,ing on a waterline modelof an American warship.

PROBABLY there is no hobby so popularto -day as model aircraft constructionamong both the young, who are always

keen on many things, and those of riper years,who have to firewatch and get tired of playingdarts and dominoes and look for somethingmore constructive to do.

The appeal of model aircraft may be partlydue to the fact that there are more sets ofparts available ; but the pastime that has alwaysappealed to me has been that of water -linemodels of ships, whether they be of the Mer-chant Navy or .of the world's fighting -fleets.

Here again there are numbers of sourcesavailable for drawings and sets of parts,including small sheets of instructions anddrawings of warships issued, free of charge,by the National Savings Committee ofWestminster, London, in connection with theWar Savings Campaign.

In view of this increased interest latelyin the building of model ships, the Editorhas asked me to give a few main hints in thisarticle, based on waterline model construction,not -dealing with any specific ship, but usefulto all those who are interested in the craft.

Useful Instruction SheetIn connection with this I feel cannot do

better than recommend an excellent sheetof instructions andhints on the construc-tion of waterline shipmodels issued as alarge blueprint by Mr..C. Swift, of Ainsdale,Liverpool, and obtain-able, price 3s. 6d.,post paid, fromBassett-Lowke, Ltd.,head office, Northampton, or from theirLondon or Manchesterbranches.

. Reproduced here-with are two of thesketches from thissheet, which also in-cludes "close-ups onthe construction ofventilators, lifeboats,funnels, davits and

A waterline model of cm "I,"

windows; and indicates the isOmetric detailsof the model, the drilling of deck cards, andthe assembling of a complicated piece ofModelling like the bridge.

Mr. Swift mentions the advantage of water-line ship modelling in that the materials areso inexpensively purchased; and aims inhis description at interesting a much widerfield of hobbyists in waterline modelling.He shows clearly by his Sketches that hismodel is "standardised," eliminating allunnecessary detail and emphasising only thegeneral lines. All fittings are constructedto a standard system, which can be adaptedto any vessel -it is desired to construct.

Having. collected- the data for the ship- you

r---1

fa ocv ru I/InuandlinullUMINI MOMgimme

-*-1C CCCra

Hints on Waterline Model ShipConstruction; A Model

Sideboard

&cide CO model, you draw detailed elevationand plan -(as the two sketches -reProducedherewith), and now to the materials.

Constructional DetailsThe hull should be of hardwood, a close

grained timber like birch, sycamore or lime,the decks of medium Bristol board, andlifeboats, winches, small deck houses, etc.,of boxwood or white holly. Tine florist'swire is used for the davits, derricks andSamson's posts, and I advise a matt finishpaint as giving the best final effect.

The hull is of wood up to the first Bristol

Clm.; Destroyer, photographed on a sheet of glans.

board deck, which is cut to the sheer required,and is maintained on each deck by deckhouses of book board.

Attention is now turned to the profile cards;which are clearly drawn out as a sketch andshow windows, port and starboard lights,etc. These carefully cut profile cards areglued in position on the hull, and havingcompleted the rebate, the various decks shouldbe cut (using the hull as a template), andpainted white.

SuperstructuresUsing a fine awl, the holes for the davits

are made, the decks being carefully placedin position, after which it is time to paint

the profiles, which aresecurely glued into therebates and trimmedoff flush with thewaterline. The bowsand stern are thenpainted, and whendry, the waterline.

The intermediate0000

Elevation and deck plan of Ike waterline merchant ;hip descril:ed in the article.

deck houses are cutfrom thick book boardand tempcirary wirestanchions are placedthrough the holes inthe decks to ensurecorrect alignment.

It is recommendedto paint the davit wirewith oil paint, whichis more satisfactorythan poster paint, andthe davits do not



require gluing in as the natural tension setup at each deck will retain them inposition.

The navigation bridge details are outlinedclearly in a drawing, and this finished piece ofwork is glued to the hull, the next item beingthe funnels. These are also clearly shown invarious stages of construction in one ofthe drawings; and are glued in positionafter they have been painted.

The lifeboats are ingeniously carved fromstrips of hardwood with the aid of a pen-knife, and are all painted before lightlygluing on to the davits. When in position theyare painted buff on top to represent canvascoverings.

The ventilators, too, are of hardwoodcut, painted and lastly glued in position.

Each mast, with its derricks, is constructedas a unit, and there is generally a deck houseat the foot which forms a foundation. Themain mast is made of needles, the nest,

Model of H.M.S. " Nigeria" held in the hand.

cross -trees and gaff are soldered on, and theunit painted. Before mounting the unit, thehatches of, Bristol board should be cut andglued in position after painting. Light buffis the most suitable colour to use.

With the mast or masts in position themodel is then complete, with the exceptionof general retouching of paintwork.

Mr. Swift suggests that the model willshow to best advantage in a delicate caseand mounted on a plinth. A strip of celluloidover the painted blue surface will give atranslucent effect.

This is only a short precis of the excellentblueprint of sketches and instructions, whichI advise anyone interested in simplifiedmodel waterline ship construction to obtain.

Apart from the interest in waterline modelsby the general public and those who love thesea, we must not forget the important partthese little models are playing in the war effort,for training purposes, for instruction in details

time to time in thepopular press.

Model SideboardThinking of good

craftsmanship, I re-cently saw anotherexample o f modelfurniture from thehands of Miss JudithHughes, the ladycabinet-maker ofTavistock, who hasbeen mentioned beforein these pages. Thistime she has made abeautiful little modelof a modernised side-board, scale tin. to thefoot, and carried out ina beautifully figuredwalnut, with rosewood

Putting the fine details on a waterline model destroyer. Thelady in the background helps with the less difficult- details.

and also for identi-fication in operationsby the Coastal Com-mand, submarines,captains of shit* andvarious other waysthat have beenreferred to fromr -

knobs for the drawers, which, incidentally,all open. In the illustration you willnotice the model is supported on twolegs only. This may seem a little strange tothose who are used to seeing four legs forevery rectangular article, but the idea is toprevent the delicate legs of small modelfurniture being broken off by the young owner.

A one -inch -to -the -foot .model in walnut of a modernist piece offurniture for a post-war dolls' house.

Testing a Focal -plane ShutterSOME time ago I wrote to the query

department of PRACTICAL MECHANICSand asked for a method of testing a camerafocal -plane shutter. I was advised to try thestock method of spinning a wheel with awhite spot on it I tried this method, whichwas not successful, but the problem stillintrigued me. I had not, and still have noknowledge of the method adopted by themakers but assume that they will be strobo-scopic. Having a camera by a reliable maker,I was more interested in the method thanthe accuracy of my shutter, and I finallydevised a method which satisfied me althoughI have not constructed the apparatus.

Disc and Flash LampMy meth5d was to rotate a disC at known

angular velocity by means of a synchronousmotor. The disc operates a connecting rod,

By M. HEDLEY

one end of which is constrained to move alongparallel guides. To this end is fixed anilluminated flash -lamp bulb. The camera isfocused on the bulb in the centre of thefocusing screen so that its range of travel isfully contained on the plate. A plate is thenexposed on time, so that a complete black linewould result on the developed plate. On thesame plate, however, by means of the riseand fall front or tilting the camera in thevertical plane, other exposures are made atdifferent shutter speeds, so that the developedplate will contain one complete line on themiddle of the plate and shorter lines in variousother positions. In some positions the flash -lamp bulb may have returned on its own path,but the varying density of the black line willshow where the light was cut off. A circle isthen drawn on the plate with the completeblack line as a diameter, and the shorter lines

projected on to the circumference. Knowingthe angular velocity of the wheel, the periodduring which the shutter is open can thenbe ascertained. The speed of the wheelwould be so regulated as to produce lines ofreasonable length.

Alternative MethodSince satisfying myself on this point I have

just come across a very simple and effectivemethod. Remove the lens from the cameraand in a dark room place a neon lamp infront of the camera -lens aperture and exposea plate. The developed plate will show aseries of dark horizontal lines due to thefrequency of the alternating current. By thesimple expedient of counting the bandsand knowing the frequency of thealternating current the . shutter speed can bedetermined.



Our Busy Inventors

Button Stick" SPIT and polish " is still 'a feature of

military life, and to prevent soilingthe uniform when its buttons are beingcleaned there is used what is known as abutton stick.

The customary form of button stick consistsof a plate of rigid material having a holesufficiently large to take the head of thebutton. And there is a slot for the ring..It appears that with this type of button

stick difficulty is experienced in preventingfingers from touching the material of thegarment, and also in holding the buttonfirmly while it is being polished. In addition,a portion of the material remains uncoveredby the aforementioned slot.

To overcome these drawbacks is the aimof an invention for which a patent in thiscountry has been applied. Accord-ing to this device, the button stickconsists of two blades of metal, orany non -flexible material, movableon a pin. These blades, not beingin the same plane, when closed, willoverlap, and each blade has a slotwhich is broad enough to take thelargest size of button ring in commonuse. The depth of the slot allowsan overlap when the ring of thebinton is gripped by the bladei.

In order that the thumb'. andfinger may be inserted, holes maybe cut in the blades at the endopposite to the button end. Fingergrips, such as semi -circular slots,may be provided between thebutton end and the movable pin.

The inventor has not overlooked'badges and buckles. Rectangularslots and suitable holes may be cutin the blades for dealing withthese articles.

A spring; which may be a rubberband, is fastened to the blades inorder to assist their separation, whenthe cleaning and polishing havebeen completed. .

Fire Hose ProtectorIN case of fire when hoses like

huge boa constrictors -cross thehighway they are liable to bedamaged by passing vehicles. It. istrue that traffic may be stopped ordiverted, but, in the event of atown being raided and fires invarious parts breaking out, a con-siderable number of hoses wouldbe laid in the streets through whichadditional fire engines -and ambu-lances would be likely to pass.

An inventor has contrived animproved device with the object of providinga simple and effective method whereby hosescan be easily protected against injury.

His invention consists of a ramp enablingvehicles to -surmount these obstructions onthe road: It comprises at least one longi-tudinal bridge member practically of U -shape.This is adapted to be placed over the hoseand there are a number of triangular rampmembers at each side, having detachableconnections between them and the bridgemember, and also between adjacent rampmembers at the same side.

As a consequence, the various members ofwhich the ramp is built are detachably

By "Dynamo"connected against relative movement of thehose lengthwise and transversely.

Training Target for AirmenTO train fighter pilots and air gunners is

the object of a new device, Which is the

The information on this page is speciallysupplied to " Practical Mechanics " byMessrs. Hughes & Young, Patent Agents, of7, Stone Buildings, Lincoln's Inn, London,W.C.2, who will be pleased to send free toreaders mentioning this paper a copy of theirhandbook, " How to Patent an Invention."

subject of an application to the British PatentOffice.

One previous invention of -this kind has a

a turntable arrangement mounted on acarriage running on rails, slides, etc., so asto enable the model aircraft to be turnedabout a vertical axis.

Comfort for DriversWHEN the driver of a vehicle indicates the

course he intends to pursue, he puts outhis hand. To enable him to make this signwithopt opening the window is the aim of adevice which has been submitted to theBritish Patent Office.

An aperture is made in the window,preferably at or near one of the bottomcorners. This is of a sizt sufficient to allowthe passage of the driver's arm. It has asliding shutter which can be rapidly andeasily opened and closed. When closed it isquite secure and, if preferred, it may .be made

to lock automatically.This invention will reduce the

exposure of the driver to a minimumof cold air.

Welders at work on an M4 tank, on a positioner, in the weldingshop of an American manufacturer. The. M4 makes a new advance

in American production of heavy -armoured equipment.

carriage supporting a miniature aeroplanewhich runs on an overhead track furnishedwith a number of junction points. The.aeroplane is carried at the end of an armdesigned to be raised and lowered on a girder,depending from the carriage. Attached tothis arm is a lamp for illuminating theaeroplane.

The new invention is an apparatus which.has a model aircraft, or equivalent target,actuated by a number of reversible motorsintended to carry out movements resemblingthose of an aircraft in flight. The devicediffers from its predecessors, owing to thefact that the model aeroplane is carried by

Mobile HangarAN improved hangar has been

designed with the chief objectof providing an aeroplane shedwhich is light in weight, collapsibleyet strong, easy to transport anderect, and not conspicuous fromthe air.

This hangar, which has a prac-tically circular, rigid roof, is builtup by pre -formed parts.

The components include amainouter ring girder and radial rafters.Both the girder and the raftersconsist of a number of parts whichare detachably connected.

The hangar possesses supportingcolumns which hold the roof atthe desired height. And the roofis detachably connected to thecolumns.

The whole arrangementapparently can be erected and pulleddown with the speed of a circus tent.

Light -weight BoxTHE ideal box is light in weight,

strong, durable and unaffectedby damp and climate. An inventorhas achieved these characteristicsin a box which he has conceived.

To prodtice thii article he super-imposes on one another a series ofpaper or fabric sheets, or a com-bination of both, which have beenimpregnated with a substancesuch as synthetic resin. Thisbecomes viscid and then hardthrough being subjected to heat.

The sheets are folded to the' desired shapeand are bent over integral flap portions, sothat the latter overlap portions of the wall ofthe box. The construction is of such anature that, at every edge where adjacentwalls meet, a flap extension of one wall passesaround this edge to overlap an adjacentwall.

The article thus formed is submitted topressure between complementary elementsof a correspondingly shaped mould heatedto the required temperature.

The resulting box should thoroughly pro-tect its contents and last for a considerabletime.


248 NEWNES PRACTICAL' MECHANICS April, 1943

QUERIESciAENQUIRIESA stamped addressed envelope, three pennystamps, and the query coupon from the currentissue, which appears on back cover must be enclosedwith every letter containing a query. Everyquery and drawing which is. sent must bear thename and address of the reader. Send yourqueries to the Editor, PRACTICAL MECHANICS,Geo. Newnes, Ltd.. Tower 'House, Southampton

Street, Strand. London, W.C.2.'

Glue MouldsT WOULD be grateful if you would inform meA what mixture is needed to make glue mouldsfor casting plaster figures, etc. I have triedordinary glue but it does not hold together. Also,how are the rubber moulds made, and the mixtureof rubber needed ?-What treatment is neededin order to use plaster moulds for casting metal ?-B. Webb (Totton, Hants).VOU can make glue moulds for the purpose youA require by dissolving ordinary glue in hot waterand evaporating the solutibn down to a thick consistency,and then by stirring into the thickened glue aboutone quarter of its weight of dry whiting or somesimilar powder. The glue mixture is run, still hot,into suitable receptacles in which it sets hard to theshape of the required mould. Finally, after completingsetting, the glue mould thus prepared is immersed ina bath made up by diluting x part of commercial formalinsolution with 15 to zo parts of water. The mouldsshould be immersed in this solution for about 15minutes, after which they will be hard and completelyinsoluble even in hot water. The moulds thus pre-pared should be lubricated with a little Vaseline orother grease.

Rubber moulds are usually made by vulcanising a" mix " of raw rubber, " filler " (such as whiting, etc.),shellac and pigment (if required) in a specialty devisedvulcanising press.. The flexibility of the resultantmoulds is governed to a great extent by the degree andduration of the vulcanising treatment. From yourpoint of view, we think it will be impossible to producesuch moulds owing to the. scarcity of rubber and thehigh 'cost of a vulcanising press. A flexible mouldcan be prepared by dissolving two parts of glue in onepart of water and one part of glycerine, but, here again,you will find it almost impossible to procure glycerinefor Such a purpose.

You can, up to a certain extent, toughen plaster ofParis moulds for metal casting by mixing with the dryplaster of paris about 4 or 5 per cent. of its weight ofpowdered dextrine, gum arabic or glue. A sm1111amount (say per cent.) of finely powdered asbestosadded to the plaster of paris will also toughen it upand improve, its resistance to fracture. If, for anyreason, you desire to slow down the setting of theplaster of paris mixture, add to it a pinch or two ofcitric acid. If die setting time of the plaster of parisis to be accelerated, add a little alum to the water.

Small Water' SoftenerT WISH to construct a small water softener for

household use. Could you please give meinformation on the materials necessary, detailsof construction and the salts to be used ? Also,if and where they are obtainable ?-A. Bolton(Greenford).'THERE are many different systems of water softening,

and it is a very difficult task for the ordinaryamateur to make a satisfactory softener on a smallscale. However, if you desire to attempt the job, youmay start your experiments by obtaining an ironcylinder about two feet long and four inches diameter.This has an exit pipe at the bottom and an entrancepipe at the top. The cylinder is loosely filled with amaterial known as " artificial zeolite." All that it isnecessary to do is to trickle the water slowly throughthis column of zeolite. After a time, the zeolitebegins to lose its water -softening power, and whenthis effect takes place, the material can be " regenerated"by filtering a solution of common salt through it,afterwards swilling away all traces of the salt solutionby means of clean, soft water. You may, at the presenttime, have the very greatest difficulty in obtaining asupply of artificial zeolite. However, for this material,we should advise you to write to Sofnol Limited,Greenwich, London, S.E.io, stating your requirements,and inquiring whether the firm can assist you in regardto materials. Sofnol, Ltd., publish a very interesting

DISTANT -READING thermometers are of manyvarying types from the high -temperature variety

which utilises the expansion of mercury in a narrowsteel tube, to the delicate instruments operating uponthe vapour pressure of ether.

Since you propose to use a Bourdon gauge, we areinclined to think that a vapour -pressure device wouldsuit your needs, and we would suggest an ether -alcohol mixture containing about 20 per cent. of ethylalcohol. .The alcohol used must be as pure as possible.For very delicate work, the " absolute " variety isessential, but it is possible to get. quite good results withordinary pharmaceutical rectified spirits. In place ofthe ether -alcohol mixture, pure acetone may be tried.

Messrs. Towers, Laboratory Furnishers, of Widnes,make (or used to makeTa good thermometric thermostatcontrol which utilises a column of pure toluene expandingagainst mercury in.,a capillary tube ? If this wouldbe of use for your purpose, we imagine that such aninstrument might still be procurable from Messrs.Towers. No doubt, also, Messrs. Negretti andZambra, Holborn Viaduct, London, E.C.r, would beable to suggest other suitable. thermometric fluid foryour purpose.

Former for Electric HeaterCAN you tell me the materials to use to make

an electric fire element holder-that is, theasbestos part on which the element is wound ?I have some asbestos and plaster of paris, whichI believe these parts consist of, but I have noidea what else is mixed with them or the methodof making same.-F. J. Lawrence (Chingford).

ASBESTOS and plaster of paris are quite unsuitablematerials for making the formers employed for

electric heaters, as they would disintegrate almost atonce when in use. A special fireclay is used, such asaluminous porcelain, or sillimanite, moulded undergreat pressure and fired for I considerable time in akiln, and their manufacture is beyond the ability ofamateur construction. They can, however, be obtainedat quite a reasonable outlay from the Morgan CrucibleCo., Ltd., Battersea Church Road, London, S.W,I 1,or from Lionel Robinson, Ltd., 2/4, Staple Inn,Holborn, W.C.

Honing Device for Razor BladesT AM interested in the honing (mechanical) of

razor blades, and understand that there aresome devices which claim to do this workeffectively.

Could you give me any details of such a hone,as I would like to make one ?-G. C. Greaves(Birmingham).

Plain Leather Surfaces(Revolved manually 10 opposite

chrecttorl

A 4simple honing device for safety -razor blades.

eEVERAL forms of razor -blade sharpening devicesare marketed, the majority of these comprising

plane or concave glass or leather mating surfaces.The yo-yo type is illustrated.

The manufacturers of Rolls Razors use a planesurface of proprietary material and a special mechanismwhich reverses the blade after traversal by hand. To

reveal a little-known trick of the trade. the followingmethod is suggested. ,Use two plane surfaces of marblewhich have been lapped together with liberal lubricationby ,water, until the surfaces are highly polished. Stillusing plenty of water, insert the blade and re -hone.Always allow a blade to remain idle and age -hardenas long as is practicable before re -honing. Oil stonesare not to be recommended.

Poster PaintsIWOULD be extremely obliged if you can give

me some information on the following matter.I wish to manufacture small quantities of waterposter paint suitable for brush and spray gun.I have tried mixing equal parts of zinc oxide,kaolin and chalk with varying quantities of gumarabic, tragacanth and casco glue, using anilinedyes (water soluble) to colour, and while all ofthese give a paint of sorts, none is entirelysatisfactory. The poster paint I used to purchase(now apparently unobtainable) gave a thin, finetexture coat of good covering power, and didnot leave patchy brush marks.-W. H. Trevett(Erith).'THERE arel in the main, two general types of poster'T

paints, viz., those made with gum -dextrinesolutions and those incorporating casein solutions.Since you will doubtless require to experiment withboth these varieties, we append below formula: of eachtype. The formulte are actual manufacturing ones,which will have to be reduced for small experimentalpurposes.C056471 Paints

These all. require a casein " vehicle " made up' asfollows :Sodium caseinate . rIlb.Bentonite (or other form of china clay) .. tor:Sodium fluoridePhenol ,/oz.vWhiitcelePaint

x71b.Lithopone 131b.Titanium oxide 21b.Barytes (white) ralb.Ultramarine blue . . ioz. .

Water to .. .. 2/gals.Yellow PaintVehicle 18 Alb.Chrome yellow

. .

61b.Barytes (white) .. , . 81b.Water to .. . . z'; gals.Gum -dextrine Water Paints

These require the following three solutions to bemade up :Gum Arabic Solution

Dissolve 125l13. gum arabic in so gals. water. Aftercomplete solution, add r quart formalin.Dextrine Solution

Dissolve zoolb. best white dextrine in 5o gals.water. After complete solution, add I quart formalin.Starch Solution

Dissolve 5olb. starch in 5o gals. water. After com-plete solution, add I quiet formalin.

From the above solutions, the gum -dextrine waterpaints are mane up on the following lines :White PaintDextrine solution .. 3 gals.Gum arabic solution 4 gals.Starch solution .. z gals.Sugar syrup .. 4 gals.Titanium oxideLithopone .. 2oolb.

..Water to make 5o gals.Add I quart of formalin to finished paint.

Red PaintGum arabic solution .. 4 gals.Dextrine solution .. 2 gals.Starch solution 4 gals.Sugar syrup 'gal.WhitingBlanc fixePipnent

Note: In these forMulx the use of sugar syrup is toimpart a good gloss to the paint when dry. It can beomitted if desired, in which case the dextrine propor-tion should be increased. If, however, too muchdextrine is used, the paint surface will crack.

You should be able to obtain books on the subjectof water -paint production from Messrs. W. and G.Foyle, of Charing Cross Road, W.C.z.

'14.Et--

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(Designed by F. J. CAMM),. '10s. 6d. per set of four sheets.

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book on water softening which, no doubt, you willfind useful. ...---

Distant-riading ThermometerWILL you please give me some information

regarding a suitable medium with which to

=:=,--.:E---.

fill a distant -reading thermometer ? -E.-

Is the principle of these and of the capsules for ..."._--

thermostatic control based on coefficient of ff.expansion or upon vapour pressure ? Indicationof a promising " brew " to work over a range30-120 C. using a Bourdon gauge to indicate,would oblige.-G. A. Cary Lynch (Standish).

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Sun -ray LampT HAVE constructed, a carbon -arc sun -ray lamp

using one solid carbon bin. diameter and oneiron -cored carbon hie. diameter. The resistanceI am using is a 75o watt radiator bar and thevoltage used is 230 volts, A.C. .

Can you tell me if this arrangement is suitablefor sun -ray treatment? If so, do you think thearrangement will give off an appreciable amountof ultra -violet rays ?-H. R. DowsonLanes).AS the amount of ultra -violet rays produced by the

carbon arc is directly proportional to the amountof current used, you would obtain very feeble resultsfrom the arrangement you propose, embodying a75o watt radiator bar in series, with the arc on 23o voltsalternating current. Usually such lamps are intendedfor a consumption of about 3o amperes, either onA.C. or D.C., but if a mercury vapour lamp is employedabout 200 volts and 3 amperes would be sufficient. Thetungsten arc is another form more economical ofcurrent than the carbon arc, but requires a directcurrent circuit for operation,- and if yours is an A.C.supply a rectifier or motor -generator would be necessaryto convert the A.C. to D.C. The current:consumptionwith a tungsten arc is approximately 5 amperes. Writethe General Electric Co., Ltd., Magnet House,Kingsway, W.C.2, for their lists of artificial sunlightapparatus.

Electric Welding PlantIS it possible for me to make up a small portable

electric welding set, using either batteries orgenerator and some type of coil ?-R. Calver(Essex).ASSUMING you require towerd metal up to. say,

tin. mild steel plate, using electrodes 3132in.diameter, this would require about 7o volts to breakdown the scale and initiate the arc, and about 75 amps.at 25 volts to maintain the arc,lus an extra 5 voltsto cover the voltage drop in the leads to the weldingelectrodes. The best way to obtain this is to use aspecial welding dynamo having a high voltage drop onload. A- machine giving 75 volts on open circuit and3o volts on a current of 75 amperes would be ideal.This dynafno would have a full load output of 3o volts x75 amps, that is 2,250 watts or 2.25 kW. The dynamowould probably have an efficiency of about -75 percent., so that the power required to drive it (expressed-in electrical units) would be 2,250 0.75=3,o00.watts.One h.p. corresponds to 746 watts, so that the h.p.required to drive the.dynamo when delivering a weldingcurrent of 75 amps is 4 h.p. Since the machine is tobe portable it is probable that a petrol or oil enginewould be most convenient for driving. At the samewelding voltage of 3o volts total, the h.p. required todrive a dynamo would be practically proportional tothe welding current required.

Steel -blue Finish for Brass0OULD you tell me of any chemical treatment- for putting a " steely blue " finish on brassobjects, similar to that on rifles, etc. ? Also, isthere a reasonable -economical method for -chromium plating or silver plating brass byelectrolysis ?

Will you please inform me of the firms fromwhich the chemicals for the above questions maybe obtained ?-G. Downes -Rose (Derby).YOU can obtain a steely blue coloration on brass

by making use of the following solution :Copper carbonate, slb. ; ammonia, t quart ; water,

3 quarts.Mix the copper carbonate and ammonia fast, and

then add the water. Some of the copper carbonate mustremain in excess in the mixture. Use this bath at atemperature of 575 deg. F. and immerse the metal tobe coloured in it until the desired colour is obtained-usually from half to one hour. Finally, rinse the metalwell and dry it carefully.

The following bath is simpler, but it gives a ratherlighter blue :

Photographer's " hypo," 8oz. ; lead acetate (" sugarof lead "), 4oz. ; water, r gallon.

Use this bath boiling, and immerse the metal partsin it for some minutes until the required blue colora-tion is obtained. Finally, well wash and dry._ The brasswork must, on all occasions, be scrupulously

well cleaned and degreased before the chemicalcoloration treatment is begun.

There are hundreds of different formula forsilver and chromium plating. Since we do not knowyour exact requirements in this connection, we wouldadvise you to get into touch with a firm of electro-plating material suppliers, who will be able to supplyyou with plating salts ready made up and in smallquantities. You will find this method much moresatisfactory than endeavouring to make up your ownsolutions in these days.of short supplies. Such firms are :Messrs. W. Canning and Co. Ltd., Great HamptonStreet, Birmingham, a ; Messrs. R. Cruickshank,Ltd., Camden Street, Birmingham ; ChromiumPortable Plater Sales Co., Ltd., 169-173, HampsteadRoad, London, N.W.S.

You should be able to obtain the chemicals for thebrass coloration from any of the firms of multiplechemists.

Armature WindingHAVE a vacuum cleaner motor, the armature

of which I wish to rewind. Will you pleasegive me a diagram of connections ?

The armature has is slots and commutator36 bars. I have wound quite a number of machines

with two bars per slot but the three bars per slothave puzzled me. The machine is 250V. 50, .-J. Sinclair (Tillicoultry).WHEN the commutator has more bars than there

are slots in the core of the armature the coilshave to be grouped in twos or threes for conveniencein assembly, and wound with the appropriate numberof tapping points looped oht at equal intervals. Theinvariable rule is that there shall be as many armaturecoils as there are commutator bars, so that with a12 -slot armature and 36 -part commutator there mustbe three coils grouped as one in each armature slot.In practice these are fotiner-wound and taped up as inFig. 1, with loops taken out at appropriate intervals,each loop comprising an equal number of turns, but thewire is not cut as the sections already form the junctionfrom one coil to the next. After taping up the appearanceof the coil is similar to Fig. r, and its actual internalconnections are given in Fig. 2, assuming only oneturn per coil to avoid confusing the figure.

Wimshurst IllachineIHAVE constructed a Wimshurst electrical

machine, as follows :Two ebonite plates rain. diameter, 24 strips on

each plate.What would be the maximum voltage, and

number of revs. to produce same ? Also, whatsize should be the discharging terminals?-R. Hancock (Swindon).ABOUT 90 revolutions per minute of the driving

gear speeded up three to one on the plate spindles,is the highest safe speed advisable for rein. plates.The spark length between discharging knobs isdetermined by many conditions other than the voltage,such as the state of the -surrounding air, whether dryor humid, and the barometric pressure. From platesof the size stared a tin. to On. spark would be

Fig. 1

Diagrams show-ing the triple codconnections withone turn per coil.(See reply ' toquery-ArmatureWinding.)

considered excellent. The size of the discharging knobson the electrodes might be lin. and (in. respectively.

Vulcanising RubberT WOULD he obliged if you could give meA details of a simple method of vulcanisingrubber, also of the chemicals required. I haveheard that it is possible to dissolve the rubberin a solution of sulphur chloride in carbontetrachloride, but have so far been unable toobtain any carbon tetrachloride.-J. Malham(Grove Park, S.E.i2).THE vulcanisation of rubber is not an easy proceis,

and there is no really simple or reliable mode ofaccomplishing it on the small scale.

In general, rubber can be vulcanised by means ofsulphur, or with certain compounds of sulphur, suchas sulphur monochloride.

Sulphur alone is seldom used in vulcanisation inconsequence of its uncertainty of action, its/Slownessand, also, in view of the high temperature needed forits action. In place of sulphur for modern vulcanisationprocesses, organic sulphur compounds are used, andthese are accompanied by certain complex compoundsknown as " accelerators " which speed up thevulcanisation process. Usually, these acceleratorsrequire, also, the use of zinc oxide for their functioning.

In your own instance, you do not state what type ofrubber you wish to vulcanise and to what degree ofvulcanisation you wish to take it. We think, however,you would find sulphur monochloride to be the bestvulcanisation agent for your purpose. Sulphurmonochloride is a yellow, evil -smelling, corrosiveliquid which is soluble in carbon tetractoride or incarbon disulphide. Your best plan is to dissolve aboutso parts of the sulphur monochloride ut 90 parts ofcarbon tetrachloride or carbon disulphide and toplunge the rubber article into this solution for about aminute and a half. It is then placed in a warm oven forthe solvent to eVaporate, and finally it is washed in adilute solution of soda in water, rinsed agd dried.

The extent of vulcanisation is mainly governed in theabove instance by the strength of the sulphur mono -chloride solution and the time of immersion of the rubberarticle in it. With certain types of rubbers, this process

is quite satisfactory, but we do not guarantee that itwill work with all varieties of rubber. It will notwork with any synthetic rubbers.

Sulphur monochloride is a product of ImperialChemical Industries, Ltd., Millbank, London, S.W.r,but we do not think you will be able to obtain it insmall quantities from this source. Your best plan is topurchase it (along with carbon tetrachloride or carbondisulphide) from a firm of laboratory chemical supplierssuch as Messrs. F. E. Becker & Co., 17-29, HattonWall, London, E.C.1, or Messrs: A. Gallenkamp & Co.,Ltd., 17-29, Sun Street, and 1-3, Clifton Street,Finsbury Square, London, E.C.z.

Rewinding a Vacuum Cleaner MotorT HAVE an " unwound " electric vacuum cleanerA motor, and wish to use same for a smallemery wheel drive. I shall be pleased if you wouldinform me as to the windings suitable for 230 -voltsingle-phase Hargreaves (Preston).THE motor you have in an unwound condition

can be wound suitably for driving a small grindingwheel, but will have to be series connected in orderto operate on A.C. This means that the speed will bevariable with the load, and unless you attach a fan orsome automatic means of preventing excessive speedwhen running light there is a possibility of burstingthe emery wheel or damaging the armature windings.Without artificial ventilation, such as present in avacuum cleaner, the power available will be verysmall in any case, say from 1, r6th to r ,2oth h.p. at4,000 r.p.m. The winding recommended will be asfollows :Armature -26 coils, grouped two per slot in the /3 -slot

armature, each coil with 68 turns of No. 36 S.W.G.d.s.c. copper, coil span from slot r to slot 7 inclusive,and lap -connected to the 26 -part commutator.

Fields -2 coils, each containing r,000 turns of No. 3oS.W.G. enamel and s.s.c. copper, in series with oneanother and series connected to the armature.A 4in. propeller type fan fixed to the shaft extension

at one end would restrain the speed from becomingexcessive; and at the same time help to -keep the motorcool.

Ultra -violet RaysT HAVE constructed an ultra -violet ray lamp,A using a mercury vapour bulb-So watt-withthe outer sheath cut off, and the necessary choke.For a reflector I am using a glass parabolicreflector which is apparently silvered at the rear.

In the first instance, I am not sure whether thisreflector is effective for this kind of light, or if itshould be painted over with aluminium paint, or,on the other hand, should I use an aluminiumreflector ? If so, could you supply the addressof any firm from which I could purchase one ?

I have been using this lamp for a week or twonow, and thg effect is that it will- burn more orless one spot and not seemingly diffused intoone broad beam as I should prefer it, the spotapparently coming from direct radiation from thelamp.-G. C. G. (Birmingham).THE therapeutic effect of ultra -violet rays depends

much upon the wavelength, and exercisesdistinctly different effects according to the degree ofpenetration. The spectrum known as the near "region, including waves from 4,000 to 3,000 Angstrt-munits are much more penetrating to the human body,whereas the rays in the " far " region of the spectrumranging between 3,000 and 1,800 AngstrOm unitshave a powerful bactericidal action. More tonic effectscan be looked for with the longer wavelengths, whilethe shorter waves are more used for open wounds, etc.An aluminium polished reflector is to be preferred tosilvered glass, and if erythema or burning is experiencedin one spot, the remedy is to alter the distance from thereflector to the body so that the focus of the rays ismore dispersed. It is possible you may still be able toobtain reflectors and equipment for such apparatusfrom the General Electric Cc., Ltd., Magnet House,Kingsway, W.C.2.

BOOKS FOR ENGINEERS--:

Gears and Gear Cutting, 61-, by post C16.Workshop Calculations, Table: and Formulae,

61-, by post 6i6.Engineers' Manual, 81, ty post 91-.Fractical Mechanics' Handbook, 1216, by post 131-.Engineers' Vest Pocket Book, 716, by post Bi-.rractical Motorists' Encyclopaedia, 1016, by

post 11I-.Motor Car Principles and Practice, 61-, by post 616.Wire and Wire Gauges (Vest Pocket Book),

316, by post 319.Diesel Vehicles : Operation, Maintenance and

Repair, Si-, by post 516.Dictionary o1 Metals and Alloys, 716, by

post 81 -Watches : Adjustment and Repair, 6!-, by post (16Plant Engineer's Pocket Cook, 61-, by post 615.Screw Thread Manual, 61-, by post 616.Mathematical Tables and Formulas (Vest Pocket

Book), 3/6, by post 3/9.



Behind the War Effort . . . .

Day in, day out the printing presses of this companymaintain a ceaseless flow of technical books andperiodicals-instructional books on workshop practicefor personnel in war industries : trade and technicaljournals providing the industrial intelligence servicebehind the war effort.

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Printers & Publishers of Technical Books & Periodicals

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The Compound Slide RestNote the two -point location of the compound slideto ensure rigidity ; micrometer dials to feed screws ;generous dimensions of the cross slide. All slidesare hand scraped and individually fitted. For thepresent, Myford Lathes are only available to holdersof M.T.C. permits and delivery periods are subjectto the decision of the Control.MYFORD ENGINEERING COMPANY LIMITED,

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Used for over 30 years in Government works and by leadingengineers and manufacturers. Of all Ironmongers-in tins,8d., 1/4d. and 2/8. Ask to see the FLUXITE SMALL -SPACESOLDERING SET-compact but substantial-complete withfull instructions, 7/6.

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To -day the efforts of ourskilled model engineers are

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Azol is a one -solution liquid developer. It is veryeasy to use. All you have to do is to add water. Aquarter of an ounce of Azol and six ounces of waterwill develop two eight -exposure 21 x 31,films. Youcan buy Azol from anygood photographic Dealerin 3 -oz. bottles or youcan 'send fors, the trialoffer mentioned below. is the developerIt is much more in- to use. It bringsteresting to do your out the detail._own developfug andprinting. You miss half the fun of photographyif you let someone else do it.

Special Trial Offer :For 213 P.O. Johnsons will send you post free (C.B. only) a trial setof Chemicals, including I -oz. bottle of AZOL, to develop eightspools 21in. by 3.1in.. 4 -oz. tin ACID -FIXING, making 30-60 ozs.solution, one packet AMIDOL DEVELOPER, enough for 2 to 3 dozbromide or contact " gaslight " prints.

Address : Dept. 41.JOHNSON & SONS Manufacturing Chemists Ltd., HENDON, N.W.4

AIR SUPERIORITY

YOU KNOW HOW MUCH IT MEANS TOTHE SOLDIERS AND SAILORS FIGHTINGIN ALL PARTS OF ,THE WORLD FOR ABETTER FUTURE . . .

EVER SO OFTEN IT MEANS THE MARTLETTAKING OFF THE FLIGHT DECK OF ANAIRCRAFT CARRIER TO PROVIDE THE

PROTECTION REQUIRED.

FOR THE MODELLER THE MARTLET IS ONEOF SOME THIRTY 'PLANES HE CAN BUILDFROM AIRYDA PLANS. IT IS A SMALLMODEL -PRICE I/8 -AND YOU CAN FIT ITWITH FOLDING WINGS.

ASK ALWAYS FOR AIRYDA MODELAIRCRAFT CONSTRUCTIONAL KITS ; IF

THEY ARE DIFFICULT TO GET, PLEASE BEPATIENT; AND ASK AGAIN FOR AIRYDA.

THE GRUMMAN MARTLETNAVAL FGHTER (F.A.A.)

NATIONAL MODELLERS SUPPLYAIRYDA WORKS ST. JOHN'S RD. HUDDERSFIELD

4



.41

GALPINS-ELECTRICAL STORES-

" FAIRVIEW "LONDON ROAD,WROTHAM, KENT

Please Note Change of AddressTHIS BUSINESS IS NOW TRANS-FERRED PERMANENTLY TO THEABOVE ADDRESS, WHERE ALLMAIL ORDERS WILL RECEIVESTRICT PERSONAL ATTENTION.

TERMS : Cash with order. No C.O.D.

Regret on Orders can be accepted fronEire or Northern !reload.

ELECTRIC LIGHT CHECK METERS,well-known makers, first-class condition,electrically guaranteed, for A.C. mains200/250 volts 50 cy. 1 phase 5 amp. load,101-each:10 amp. load, 12/6, carriage 1/-.LOUD RINGING BELLS, working on110 v. D.C., Sin. diameter gong (bell metal)plated, waterproof, new, 32/6, carriage paid.1 K.W. TRANSFORMER, input 100 voltsat 100 cycles, single phase, output 10,500volts. centre tapped to earth. Price14/101-, carriage forward.HEAVY DUTY CABLE, V.I.R., andbraided, in first-class condition, size 37/13,lengths 30 to 40 yards. Price by the length,5/- per yard, carriage forward, or 7/- peryard for short lengths, carriage paid.200 AMP. SWITCH FUSE, three-way.Ironclad, unused. 400 volt, size overall30in. x 12in. x 12in., maker E. N. Bray,1.t/f. Price £6, Carriage forward.1 K.W. ELECTRIC FIRE Element, size16in. x 1 lin. x lin., for 220 v. mainsA.C. or D.C., as new, 6/- each, post free.POWER PACKS for smoothing, etc..consisting of two 300 ohm chokes andtwo 2 ofd. condensers. Price 8/6, postfree.ROTARY CONVERTER, D.C. to D.C.Input, 12 v.; output, 1,100 v. at 30 fit/a.Ex R.A.F., condition new. Price 50/-,carriage paid.HEAVY DUTY KNIFE SWITCHES, D.P.,D.T.. quick break, 100 amp., in first-classcondition. Price 20/-, carriage paid.X-RAY TRANSFORMER, in oil -filled tank,medium size, input 520 volts, -50 cycle,1 ph. output 45,000 volts as 2 kW.,intermittent rating, in perfect order.Price £20, carriage paid.ROTARY CONVERTER, D.C. to. D.C..input 48 volts; output 2,500 volts at1 kW., condition as new. -Price £10,carriage paid:

WATT WIRE END Resistances, new andunused, assorted sizes (our assortment),5/6 per doz.. post free.ROTARY CONVERTERS, D.C. to D.C.,permanent magnet. fields, small size,windings not guaranteed, ball bearing,contained in cast alli bOx, size 12in. x 4in..x 4in. Price 15/-, carriage paid.AIR PRESSURE GAUGE, Dip. dia., ingunmetal, reading 0-4,000 lbs. per squareinch, conditiou as_new. Price 50/-, carriagepaid.SOLID BRASS LAMPS (wing type), one -hole mounting, fitted double contact. smallB.C. holder and 12 -volt 16 watt bulb.3/6 each, post free, or 30/- per doz.,carriage paid.DYNAMO, output 20 volts.,15 ampsshunt wound, slow speed, tall bearing,condition as new. Price 53/10/-, carriagepaid.TWO -GANG Variable condensers, smallsize, capacity .0005. Price 3/-, post free.HEADPHONES, la) ohm, secondhand,complete with headband and cords, inperfect working order. Price 7/6 per pair,post free.INSTRUMENT METAL RECTIFIERS, byfamous maker, .10 m/a full load, convertyour D.C. actor to A.C. working. PriceIS!- each. post free.TUNGSTEN CONTACTS.3/tain. dia., a pairmounted on spring blades, also two highquality pure silver contacts 3 /is dia., alsomounted on spring blades, fit for heavyduty, new and unused ; there is enoughbase to remove for other work. Price theset of four contacts,.5/-, post free.220 VOLT DYNAMO 9 AMP output byLancaster Dynamo Co., shunt wound,speed 1,500 R.P.M., condition as new.Price £10, carriage paid. POST OFFICE RELAYS, small type, highresistance, twin blade, very low milliarapoperation, as new. Price 7/6 each, postfree.

YOU CAN TIN ANY METAL QUICKLY AND EASILYwith

HOYT'S TINNING COMPOUNDconsisting of powdered metal combined with an active fluxNO SEPARATE APPLICATION OF FLUX, SOLDER OR TIN REQUIRED

JUST CLEAN THE JOB AND FOLLOW DIRECTIONS

Heat the work and just sprinkle the powder evenlyupon surface to be tinned. The flux should " boil "and its cleansing action will be assisted if the surfaceis scrubbed with a wire brush at this stage. Whenflux has all melted and the -surface is tinned evenly,all over, remove from heat and wipe with a clean rag.

Price 6,- per lb. nett carr. paid.HOYT METAL CO. of GT. BRITAIN, Dept. PM, DEODAR RD., PUTNEY,

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500 ohms. coil. Counting up to 9,909. Operating from 25 v. to 50 v. D.C.Many industrial and domestic applications. (S.H., ex -G, P.O., all perfect.)

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yourself. Every man and everywoman has within himself and her-self a mine of abilities that lie dor-mant, ready to be brought intoservice through the proper trainingof the mind. This is the time tobring them forth and- to use them -for -the benefit of yourself, yourdependants and your associates.

Remember-Everything you do ispreceded by your attitude of mind.The Pelman Course is taught by

correspondence only. There are noclasses to attend. The problems ofeach Pelmanist are consideredseparately by highly trained, sym-pathetic instructors. Under thisunderstanding system, even themost timid student gains self-confidence immediately.

The Pelman Course is fullydescribed in " The Science ofSuccess." The Course is simpleand interesting and takes up verylittle time ; you can enrol on themost convenient terms. The bookwill be sent you, gratis and NAfree, on application to :-

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P E LAI A 31 (OVERSEAS) INSTITUTES:NEW YORK, 271, North Avenue, NewRochelle. MELBOURNE, 396, FlindersLane. 10BANNESBURO, P.O. Pox 402n.DURBAN, Natal Rank Chambers (1'.O.Bor 1489). DELO!. 10, Alipore Road.

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April, 1943.

THE CYCLIST 49

VOL. XI APRIL, 1943 No. 254

All letters should be addressed tothe Editor, " THE CYCLIST,"Cjeorge Newnes, Ltd., Tower House,SouthamptonStreet,Strand,London,

W.C.2.Phone : Temple Bar 4363

Telegrams : Newnes, Rand, London

Comments of the Month

CompanyAPROPOS our recent explanation of the

legal position concerning the conversionof a private cycling club into one

of limited liability, there seems to be -amisapprehension that the club -is limitedfrom the moment of passing the resolution em-powering the committee to form the club into.a company. The committee has not power toreach this decision on its own ; such decisionmust be taken at an annual general meetingor a special general meeting. Unless the rulesare put before the members at such meetingsa further general meeting must be held beforethe papers are filed with the Registrar ofCompanies. If the rules are changed without theapproval of the members the registration canbe upset. The rules which govern the club must be sent to the registrar with theapplication for registration, and these must beapproved l3y the members. The memorandumsubmitted to the registrar need be signed byonly seven members, and so members need tobe careful that there is not a coup d'etat.

Usually when a club becomes a liinitedliability company (but not always) it is becausethere has been trouble or trouble is brewing.In an imaginary case seven people couldregister the company (any seven members,not necessarily committeemen) and becomethe proprietors of the club, inviting themembers to rejoin under the terms imposedby the new rules. It is important thereforefor members of clubs which are thinking ofmaking this change to make quite sure thatthey are kept fully informed of all that ishappening and at the meeting which makes thevital decision to see that the old rules are eithercarried on or modified by general ,consent.

The British League of Racing CyclistsTHE London League of Racing Cyclists,

which is a section of the British Leagueof 'Racing Cyclists, at a recent meetingplanned a list of events for the present season.Their first mass -start race, for which policesanction and promise of co-operation havebeen obtained, is to be held in May. Althoughthe N.C.U. centres have - largely decidedagainst mass -start racing on the open road, acomplete referendum of all of the clubs,adherent to -the N.C.I.J. has not yet beenobtained. Certainly a high percentage of theN.C.U. centres have voted negatively. The'hew movement, however, is not daunted bythis negation, and equally proves that a largenumber of cyclists do want this form of race.One club has solved the difficulty by dividingitself into two parts, one for mass -start, andthe other to operate in the ordinary way.The Ealing C.C. remains adamant and hasrefused to reaffiliate to the National bodies.In the meantime, the London League ofRacing Cyclists have planned a programmeof 32 road events and hill climhs, including aleague road and time trial championship,three, open road races, three " 5os," six " 25s,"one " too," three team time trials', fourcircuit events,,a tandem " 3o," a hardrider'sevent, two hill climbs, two ladies' " los,"and two ladies' " 25s." The league will alsopromote several track meetings. - Several

Registrationprominent cyclists are associated with theleague.

Salvage-An Appeal to Cyclists

THE Directorate of Salvage and Recoverymakes a special appeal to cyclists.

It says" That empty oil tin, for instance, should

be squashed fiat, together with any other tinsyou may find, and put out for salvage. Itwill go to the blast furnaces to be melteddown, and can be made into anything from amachine-gun belt to a marine engine. Ifyou have some old nuts or bolts, don't despisethem because they are so small. Put themin one of the tins and let them go the sameway. The country needs every scrap ofmetal it can get.

"If you have an old, worn tyTe or a splitinner tube, it will make a most valuablecontribution, for the rubber situation isserious, and the demand for " reclaim " tomix with new rubber for making bombertyres is almost insatiable.

"Even old puncture patches or valve -caps have their value, and so have odd lengthsof hose. Your scraps can be incorporated inthe making of collapsible dinghies, life-savingjackets, or barrage -balloons, as well as tyres,or they may help to provide gas or oxygenmasks for airmen, surgical equipment, orfireLhose.

" But there will still be other things usefulfor salvage when you clean out your shed.What about old maps or itineraries, bills, orold newspapers ? Pulped and processed, theywill make shell containers, cartridge wads,demolition cartons for Commandos, essentialparts -for mines and bombs, or trench mortarcarriers.

"Old rags-and what shed will not containsome fit only for salvage ?-are badly wanted.According to their quality, they may become

Waste PapDESPITE the efforts made by all

sections of the community, thereis a weekly deficit of several

thousands of tons of waste paper for warneeds ; too,000 tons are urgently neededto meet the immediate demand of warfactories, to Supply packaging - for food,medical supplies, etc., and for other essentialpurposes. With the much reduced amountof -paper being put into current circulation,inevitably the day-to-day collections of wastehave suffered. Therefore an intensive efforthas to be made to dig out the accumulations ofbusiness houses, manufacturing concerns,professions, institutions, etc.'

Although much has already been done inthis direction, it is estimated that there arestill hundreds of thousands of tons to beobtained from these sources.

Every business and manufacturing concernis urged to appoint a member of its staff assalvage officer for the shop, store, factory oroffice. With the backing of the managementhe should make himself responsible for the

By F. J. C.

uniforms, engine wipers, paper for maps andcharts, or cotton wool for surgical dressing."

" 65 "1nN February 16th of this year the National1' Cyclists' Union celebrated its 65thbirthday. In those years it has done a greatamount for cyclists and cycling. TheInaugural Meeting was held at the GuildhallTavern, London, on February 16th, 1878,when the first rules were drafted. One ofthe earliest problems it had to tackle werethe provisions of the Highways Act. TheN.C.U. was originally founded under thetitle of the Bicycle Union, and theamendment to the Highways Act which itopposed was designed to prevent cyclistsfrom using the highway. In those years acyclist was considered a menace. The actionof the Bicycle Union secured the rejectionof the amendment. The Bicycle Unionchanged its name to the National Cyclists'Union in 1883. It has a good record ofservices energetically and cheerfully rendered.Naturally it has been criticised and feeling attimes has run high, both for it and against it.It has weathered the storms, and will continue -to experience them. To -day it is wrestlingwith the controversial mass -start problems.Time must show whether its policy is right.The present attitude of the Union is that ifchanges are necessary they are prepared tomake them but they require the authorityof their adherent clubs before such changesare made.

Veterans' Time Trial Association

THE Veterans' Time Trial Association hasbeen formed. It solicits membership

from all the- over go's Who still desireto race against those of their own generation,but at the reduced pace which many find acorollary to 'the' forties. But why veterans ?We thought men in the forties were middleaged.

er Urgenteffective collection of every scrap of currentwaste. Of greater importance, he shouldexplore every possible opportunity of turningout all the old and mainly obsolete records-old correspondence, files, ledgers and otheraccount books, guard books, out-of-datereference books and trade catalogues, oldinvoices, receipts and cheques, copy estimates,sales graphs, blueprints, etc. Each journalwill know what eabh industry, trade orprofession is likely to have. It should be thesalvage officer's job to determine, in con-sultation when necessary with his manage-ment, not so much what can be sent to salvageas what it is essential to retain-everythingelse should be sent to salvage. Business .waste is of high quality for paper -makingand should go to waste paper merchants soas to ensure efficient sorting and grading.Shculd there not be a local waste papermerchant, readers should -get into touch with

the Waste Paper Recovery Association, 154,Fleet Street, London, E.C.4, who. will bepleased to help them.


50

1: ice -President Dies in AfricaLIEUT. - COL. THE HON. SOMERSE

MAXWELL, enthusiastic vice-president of King'sLynn C.C., has died of wounds in Africa. He was akeen rider.

News of Wally' MainAFTER serving with the Ark Royal on her many

adveutures, Wally Thain, Portsmouth NorthEnd C.C., is now on another aircraft carrier.

" Smiler" Vaughan SafeREPORTED missing from air operations early in

November, "Smiler " Jack Vaughan, MidlandC. and A.C., is known to be a prisoner of war.

" Bert" Houghton in R.A.F.APPRECIATED vice-president of Twickenham C.C.

and former joint holder of several Nationaltandem -tricycle records, " Bert " Houghton is now inthe R.A.E. Last year he covered no fewer than14.737 miles.

Walsall TrophyTHE family of the late Cpl. D. J. Kinsella, a keen

time-trialist and tourist and secretary of theWalsall C. and A.C., have presented the club with atrophy to perpetuate his' memory. The Corporal waskilled in action while serving in the Middle East.

News of Geoff OuthwaiteWELL -known member of a Bradford Cyclists'

Club, Geoff Outhwaite, who left .this countrysome years ago to take up a post in Shanghai, is nowknown to be safe. He left the city in the last boat, andis now making up for restricted cycling activities.

Ridley C.C. LossOFFICIAL

confirmation 'is to hand that GeorgeForster, former secretary of the Ridley C.C.,

has been killed in action. He was an air gunner.

Norwood Paragon DistinctionTHREE members of the Norwood Paragon C.C.-

all of whom are also keen bicycle-poloists -havebeen decorated for bravery.

Twickenham'; JubileeTWICKENHAM C.C. celebrates its Diamond

Jubilee this year. The latest club member tojoin the Forces is J. G. Witcombe, club champion, and

.a rider who showed outstanding promise. More thanSo per cent. of the club's pre-war members are in theForces.

H. N. Petty MissingFORMER secretaryand captain of the Anerley

Leading Radio Mechanic 'H. N. Petty is missingas the result of enemy activity at sea.

THE CYCLIST

What's In a Name?TN the Harrow and WembleyA area there has been formed acycling club with the nameof :; Roadster Cycling Club."Officiali state that the title in noway indicates the type of machineused but that- the name means"sensible road user."

Clubman's ExploitLEN GUNN, member of South-

western Section of the N.C.U.,was one of three lance -corporalswho captured- 30o Italians. Hewas recognised by members in aPress- photograph-a copy ofwhich has been secured for theclub's archives. '

St. Christopher

Club CasualtiesORMER Essex grass trekF champion, Jack Ivory, South-

end and City Wheelers, has beenkilled in action. Another memberof his club, Claud Hutton, is

'reported missing. News is tohand that Albert Gainsworthy,Gainsford , Wheelers, has beenkilled in action while sgrving Withthe Royal Navy.

Cycling Film " Stars"AFILM, now near completion,

" Shorts and Saddles," fea-tures members of West HeathCycling Club of Birmingham.

Manchester Wheelers'Jubilee '

MANCHESTER Wheelers areconsidering a special pro-

gramme of events by which tocelebrate their Diamond Jubilee.

C.C. LOssTHE Leeds St. Christopher's Cycling Club are

mourning the death of, yet another of theirstalwarts : Sergeant -Pilot P. F. Nettleton, former timetrials secretary of the club.

A New Tricycle ClubALTHOUGH the members state that it is in no way

formed in opposition to the Tricycle Association,a new three-wheeler club (which is open to women-the T.A. is not) has been launched in the Midlandsunder the title- of the.National Tricycle Club.

Resignation of Louis EwingLOUIS EWING-of " Fullers of Girtford "-has

resigned the secretaryship of the Poly C.C.His business now takes him into the country.

Killed in the Middle EastBY the death on active service in the 'Middle East

of Sergeant -Observer R. Almond, R.A.F.V.R.,Rotherham Wheelers have lost their second member inthe war.

King's Lynn ActivitiesAMONG members of the king's Lynn C.C, serving" overseas is. Lieut. William Pryor-holder of the

' club 25 -mile record-who is in North Africa, andBattery Sergeant-Major J. H. McLaren, who is in theMiddle East.

Farewell Party to Pyramid StarAFAREWELL party was given to H. L. Johnson,

Pyramid Road Club -star rider, prior to joiningthe Fleet Air Arm. Fie isto train as a pilot.

Cyclist MessengersS OUTHAMPTON

Wheelers have beenasked by the local Fire ForceCommander to form acyclists' messenger servicein the city for use in theevent of other means ofcommunication breakingdown.

African CasualtiesTWO members of South-

ampton Wheelers, bothof whom were serving inthe Hampshire Regiment,have been posted Missingfollowing operations inNorth Africa. They areCaptain F. Prince and Pte.J. Pullen. The last-namedwas a prominent trackrider.

April, 1943

Plymouth's InvitationAN open invitation to serving men in the Plymouth

area to take part in club fixtures is given by thePlymouth Corinthian C.C., whose secretary is Mr. B.Saunter, z6, Rosslyn Park Road, Plymouth. Thirty-fourof the club's members are serving.

Clubman HonouredQ SIGNALMAN TFAIAS HIGG I NBOTFIAM,

member of Yorkshire Clarion C.C., has beenawarded the Polish medal " Krgyg Walecznych," theequivalent to our Distinguished Service Medal.

Club Re-forinedTHE Crest C.C., of Ilford,. Essex, has been

re-formed.

Dealer Gives ArmourALINCOLNSHIRE cycle dealer has given a suit of

armour as scrap to the Ministry of Works.

Bicycles at ,S'talingradTHE Russians collected many bicycles amongst the

booty lost by the Germans at Stalingrad.

Death of Pioneer CyclistTHE death has occurred in Edinburgh of a pioneer

cyclist, Robert S. Kennedy, at the age of 65.

Cyclists Paid £360DURING 1942 the Scottish Y.H.A. collected a total

of £360 from cycle storage charges at its hostels.

Cycling at MaltaAIR Force personnel at Malta is making use of

" bicycles for travelling between billets and airfields.

Old to NevTHE East Suffolk Education Committee is having

30o bicycles made from usable parts of oldmachines.

Chambers ConsulT`OMMIE CHAMBERS, famous Scottish mile -

eater and ex -racing man, is the new Cyclists' -

Touring Club Chief Consul for Wigtownshire.

Parish Pump GoingQ AXMUNDHAM'S parish pump, which has been

called a convenient cycle stand in the past, is tobe removed as scrap metal.

Bicycles at k25o EachlaRITISH bicycles are costing the equivalent of £250" each in Chengtu, in Free China, states a Churchof Scotland minister out there.

New West Coast Route?COUNTIES in the north-western part of England are

pressing for a new west coast road to linkLancashire, Cumberland and Westmorland.

Rubber from PapuaTHE rubber plantations of Papua are working again

following the release of native labourers whohave been helping the Allied Forces against theJapanese.

Clarion Easter MeetTHE National Clarion C.C. is holding its 48th

annual Easter meet at York this year. The annualconference, a social -dance, and other items are in theprogramme.

Next year's meet will be held in the Club's JubileeYear.

Seen by the tourist : the Redeswire stone at the summit of CarterBar, on the boundary between England and Scotland.


April, 1943 THE CYCLIST 51

Around the WheelworldBy ICARUS

Spring Sunshine." Wool Lane,

S.R.R.A. Annual LunchTHERE was a pre-war quality about the

S.R.R.A. annual lunch, which was heldat the Railway Hotel, Purley, on Sunday,February 14th, with the president, J. DudleyDaymOnd, in the chair. It was, indeed, anall-star performance. This association wasfounded in the same year as the PurleyRailway Station was built, in 1899. Thefunction was an extremely jolly and good-natured affair, and among those present wereRansom Morford, A. Shillito, E. V. Mills,C. F. Davey, H. C. Scotto, S. Amey, H.Kingsmell, Arthur Whinnett (hon. sec.),E. Coles -Webb, F. H. Grubb, H. Beurl,F. Armstrong, Harry Paul, George Lawrie,A. H. Bentley, Rex Coley, W. J. Mills,H. H. Englands.W. J. Pett and J. H. Wallace.Arthur Shillito, in an extempore speech,proposed the toast of The Association, . andpaid tribute to the work it had done, andArthur Whinnett, in response, dealt with thehistory of the S.R.R.A. from its beginning.He dealt at some length with the year 1928,which he said was the most exciting year ofthe association. No less than 16 successfulattempts on records were made that year.The toast of The Record Breakers wasproposed by H. H. Bartlett, with replies fromDavey, Grubb and Morford. The toast ofThe Visitors and Press was proposed byJ. Dudley Daymond, who expressed delightthit the editors of the cycling papers, W. J,Mills, H. H. England, F. J. Camm andR. B. Coley, had made it their pleasant dutyto be present. W. J. Mills, in a witty speech,H. H. England and F. J. Camm replied onbehalf of the Press. The latter made thepoint that whilst the S.R.R.A. had been

considered as a localassociation, it was inreality a national associ-ation, in that it governedfrom a national point ofview records made on thesouthern roads. Mr. A. H.Bentley proposed the toastof The Chairman withbrevity but sincerity,based upon a long associ-ation with him. Musicalhonours were accordedthe chairman, who suit-ably replied. It was3indeed, a most pleasantfunction.

Save RubberTHE National Commit-

tee on Cycling hateissued' the followingstatement :

" Cyclists can use theirbicycle pumps to savehundreds of tons of rub-ber.

" In peace -time wellover one thousand tonsof it went to the makingof bicycle tyres everyyear; so bicycles inBritain must be carryingtwo or three thousandtons of rubber roundtheir rims to -day.

" Thousands of these' bicycles are being riddenon tyres which are under -inflated ; and under -inflated tyres wasterubber. They have only

Midhurst, Sussex. half the life of tyresproperly blown up.

" Tyres pumped hard not only save rubber :they give speedier and more enjoyable riding.May we therefore appeal to every cyclist ?All hands to the 'tamps !

" And a flint picked up to -day may causea puncture to -morrow : so why not look tothe covers and pick them clean ? "

Solution TubesTHE tyre manufacturers state that there

must be in Great Britain at the momentseveral million tubes of rubber solution forrepairing cycle and motor tyres. As thesebecome empty, would their owners mindtaking the trouble to drop the used tubesinto the salvage bin at the nearest chemist's ?

Toothpaste makers have been kind enoughto accept the suggestion of the Tyre Manu-facturers' Conference that cyclists andmotorists should put solution tubes in thebins for empty toothpaste tubes. All profitson the sale of metal tubes go to the Red Crossand St. John Fund. Without cost tothemselves, therefore, contributors of usedtubes help the war and the nursing servicesby one simple act.

Tyres Without TubesAN American engineer, John McGay, of

Tulsa, has invented a method of sealingtyre casings to wheel rims and inflating themwithout using inner tubes.

When over 600 car owners of Tulsa hadbeen persuaded to test this invention andhad proved it to be successful, the cityauthorities of Tulsa decided to follow suit,and to -day all city -owned vehicles with drop -centre rims are tubeless. The Douglas

Aircraft factory at Tulsa, too, are changingover all their cars and trucks to this newmethod of tyre inflation.

The principles adopted to adapt existingwheel and tyres are extremely simple. Firstthe rim of the wheel-which, of course, shouldbe drop-centred-is cleaned and smoothed.Then a valve, preferably oversize, is fittedinto the regular valve opening and securedwith a lock nut and rubber washer. Holesand cracks in the tyre are' filled with coldpatches or vulcanised and all irregularitiessandpapered smooth, especially on the beads.The tyre is then mounted and blown uprapidly and tapped at the same time to ensurethat the beads seat themselves evenly.

Once the tyre is inflated, the wheel andtyre are immersed in water for the usualbubble test. Sometimes, in order to sealthe smaller cracks, it is necessary to inject apint or so of liquid cement. It is claimedthat once the tyre is made airtight it requiresonly the usual care. Sounds too good to bepractical.

' Wings for Victory'; '

DUNLOP RUBBER CO., LTD., haveinvested £150,000 as a contribution to

London's Wings for Victory Week whichclosed last month. It has been allocatedamong the following boroughs where thereare Dunlop offices, warehouses or factories :Westminster, £60,000 ; Edmonton, £40,000 ;St. Pancras, £25,000 ; and Lambeth, Stepney,Greenwich and Finsbury, £6,250 each.

Road AccidentsROAD deaths in Great Britain in January

totalled 589-an average of 19 a day.In addition, 10,403 people were injured,2,601 of them seriously.

Compared with January of last year, when681 were killed and 12,770 injured, it was asafer month for all classes of road users exceptpedal cyclists. The number of cyclists killedwas 87, an increase of 16, and there was alsoa marked rise in the number of cyclistsseriously injured.

Of the 370 pedestrians killed, two-thirdslost their lives in the black -out. The totalnumber of black -out deaths among all roadusers was 335, a reduction of 20 per cent.

Ainong the daytime accidents were most ofthe 75 fatalities to child pedestrians and 'childcyclists. This figure for January has remainedalmost unchanged for the last three years, andis substantially above the pre-war level.

Past investigations have shown that thevictims of these accidents, other than pedalcyclists, are mainly children under eight yearsof age. The saving of these young lives is aproblem which can be solved only by com-bined efforts on the part of the parents, drivers,and teachers.

All road users are warned against the dangerof allowing themselves to be lulled into afalse sense of security. Though civiliantraffic is lighter, the death rate on the roads isnot lower, but higher, than before the war.On the average, at least three more lives werelost on the roads every day in January of thisyear than in the last January of peace -time.

Broken Milk Bottles

THE Ministry of Food has made an ordermaking it an offence for anyone to

misuse or wilfully destroy a milk bottle orto retain it unreasonably. Cyclists have beenthe chief sufferers from the menace of brokenglass, and in these days of rubber shortage itis a serious matter when a tyre is ruined dueto the carelessness of those who place milkbottles in a position where they may be easilybroken and pieces strewn in the road.This has been a problem for many years, andwe hope now that the order has been madethat the offenders will be taught a summary'esson in the way of fines.


52 THE CYCLIST

Stoke Fleming, near Dartmouth.-The church contains a veryancient brass (1361), probably the oldest in Devon.

Salvage!IT is strange how sometimes voices from the

pat seem to proclaim just the words andsentiments which fit our present situation-in this year of destiny 5943. I am thinkingof some words spoken by Admiral Blake in1653, and which have very aptly been usedin a recent Dunlop advertisement. Thisis what the gallant Admiral said so longago :

" We do very much want paper andcanvas for cartridges, also old junk forwads, without which our powder will. dous little good."

Now, what about those words as beingfitting for a modern, bang up-to-the-minutesalvage campaign ? Truly there is nothingnew under the sun, and I am sure youdid not think that the Old Countryhad its " waste paper drives " away backin 1653 !

Post-war PlanningTHERE is much talk now about " after -

the -war planning," and it is good thatwe should all be thinking of this vital matter.But I do trust that some of the theorists andexpert planners will not be allowed to destroythe naturalness of England. We do not wantan England devoid of rambling charm ; we

' do not want an England conceived andplanned on a drawing -board ; we want afree England, with natural beauteous growth,and while we shall be well rid of slums anddirt and disease, we must see to it that we retainthe good things which have grown so slowly,and so beautifully, with the years. In fact,,we need planners with brains and hearts,and if I ask also for a little sentiment,well, it is sentiment which makes theworld tolerable. A standardised England,with each shire looking like its sister, wouldbe horrible.

April, 1943

CycloramaBy H. W. EP

Dunlop PatchesTHERE is no end to

the changes broughtabout by the war in con-nection with products andpackages familiar to usover the years. I havebeen advised that thefamiliar Dunlop " Reddi-fix " and " Vulcafix "patches will now be brown-the well-known red tintgoes, as in some way oranother. the new colourmeets war -time require-ments better. There is,of course, no change inquality.

Rubber ShortageTHE Ministry of Supply

has launched a newadvertising campaign aboutthe rubber shortage, andsome strong and vigorousadvertisements are appear-ing in the technical papers.There is no doubt aboutit, rubber is almost ourNo. I war material, for, aswe all know, this war is a" war on wheels "-andnot a 'plane could take theskies without tyres. Andnot a tank could forgeahead in the_ desert landsof Africa without tyres. So

it is up to all of us to save rubber, to salvagerubber articles, to take extra care whendriving. And don't let us run away with anyfoolish ideas that the 'vast raw rubber outputof Malaya can be made up from supplies in,say, Brazil or Mexico. Just to show theposition : in the year 1938 the combinedoutput of Brazil and Mexico was some28,000 tons-whilst we used to get about340,000 tons from Malaya annually !

Signs of SpringDING WINTER has been kind to us !

Not for years can we have had such amild February; and here is March, giving ussunshine such as we might expect in June !As I write, my eye catches sight of the purpleand yellow crocus blooms in the garden-thesun glints them, and the yellow blossoms arelike burnished gold. And sheeny -feathered,tawny -billed blackbirds pop in and out _of thelaurel bushes on the lawn, and somewherenear a hen is cackling proudly, no doubtfeeling justifiably proud of her aid on theFood Front. Yes, a genuine spring morning,and while it is the fashion to smile at poets,and treat William Wordsworth. with disdain,I feel like reading a sonnet and dancing in awoodland glade to the immemorial pipes ofPan. Spring sunshine-7one of the thingswhich even Hitler cannot subdue or conqueror terrorise !

Better Lighting for CyclistsT EXPECT that the eyes of many cyclists", gleamed with joy when they caught sightof that little announcement in the press aboutbetter lighting. Mr. Herbert Morrison was,I believe, an ardent cyclist himself at onetime, so maybe he thought kindly about theproblem ; anyway, he announced recentlythat the top half of the glass of a cycle lampwill be black, as at present, but the inside of

the lamp will be painted white. The HomeSecretary said " a big improvement." Andanything which gives us better lighting willbe welcome. There are many folk whobelieve very sincerely that the black -outregulations are much over -due for drasticrevisions, and that much could be done tgimprove matters without in any way, ..endangering security.

Roadside Cafés

JUST as the old stage -coach brought intobeing many of our oldest and best

roadside inns, so has the long-distance goods -lorry been the cause of the chain of roadsidecafés and " shacks " which dot our highways,and provide good and welcome refreshmentfor those fine fellows who drive through thenight, taking precious cargoes from Londonto Manchester, from Bristol to Birmingham,from Newcastle to Nottingham-and allover the country. They have a hard job.They have to be " tough." ' And they needpretty constant refreshment-so we have

Joe's Café," the " Jolly. Pull-up," and allthe other cheerful little places which cater,by means of coffee, tea, and sandwiches, and" fags " for the modern Knights of the Road.Good luck to them all. I noticed recentlythat a technical paper had started a featuregiving a list of all these useful roadsidepremises, and I thought what a good andhelpful eature it might prove to be. Theseplaces are a modern development which hasnot received the publicity or the prominencewhich it deserves. After the war, the move-ment' will grow, because more and moregoods will be carried by road. England'shighways will hum with more and moretraffic, even if the dreams of the " AirTransport " kings come true ! The road isthe immemorial thing, the ribbon of tradeand activity which will never die. Andwhenever I see a great lorry, laden withmerchandise, rolling along a famous highway;my mind always turns to the days when thebeginnings of that road were fashioned by theRomans, the, road builders whose workendures, who built straight, and left their -

undying memorials winding through theshires of England.

Easter CustomsEASTER ! And it is as late as can fall.

No space here to enter into all theintricate and extraordinary reasons whyEaster Day falls on any given date; it isa matter bound up with the phases of themoon, and mixed with a good many" ecclesiastical ingredients." But I think ofpast Easters, spent awheel. Of grand littletours in homely country districts, with teasat little cottages-of days when " rationing "was unknown, and one could get a " busting "meal for about one -and -threepence ! Andthe Easter season reminds one of many oldcustoms, some of them still kept up even inthese unromantic days.

For instance, there is the " Bread Dole,"which is distributed on Easter Day atEllington, in Huntingdonshire. The ancientceremony is performed in the village church,and I believe that it is a qualification thateach one who receives the " dole " musthave slept the previous night in the parish.Then there is the King's " Maundy Money,"an ancient charity distributed to a numberof widows in Westminster Abbey on the daybefore Good Friday. It is not generallyknown that the number of recipients isgoverned by the age of the King at the timeof each annual ceremony.



BY F.J. U KlkY

Worth WhileEASTER, this year, falls towards the end of April,

Shakespeare's month of pied loveliness, and ifwe get the chance of a few days along he road, I forone, shall take it. Nor shall I be in any hurry togather swift miles, but rather linger along the way andwatch the unfolding beauty of an English spring,with the thought in my mind that,seen on the back-ground of war, it is more precious than ever. I wantto Stress that point because I have come across peoplewho seem to think there should be no time left in thisworld of strife to step aside and discover, so gentlyand so easily, the magnificence of our heritage and allit means to us, and can mean to the folk who comeafter. A day or two spent among the scented lovelinessof an English spring is not merely a rest and recreation-as necessary as meat and drink to the famished-buta thankfulness for things past, and the hope andexpectation of things to come. Use Easter like thatif you get the chance, and I guarantee you are a betterand happier individual for tht change. But do forgoodness' sake, be fit enough to -make your trip, and bythat I do not mean you must be at the top of your form,or young and strong and hefty, but just competent tosit on a saddle comfortably and pedal a dozen mileswithout a rest, and then you have 4o or so miles inyour legs for a day out, and if you cannot find beautyand a sense of freedom in that range of furlongs, Iconfess I should be disappointed with you as a cyclistseeking that ultimate bourne of all humanity, a sense ofsatisfaction. Maybe you cannot wander so widelyby reason of family tics , well it does not matter, justlimit your journey without invading the sphere ofselfishness, for after all that is equally part of the freedomthat dominates and adjusts this glorious pastime ofcycling.

Make it a Graceful HabitT0 -DAY there must be very many people who have

taken to cycling because they have had to if theywish to preserve freedom of travel movement. Amongthem are folk who resent the necessity, and who whiletaking advantage of the bicycle's mobility think it ahardship to be-" reduced " to such a travel sphere. Ihave no intention of being critical of such peoplebecause they have merely adopted an attitude whichhas been common enough for many years, possiblybecause Vanity is one of the human failings. Butthere are other things in life to be vain about besidesthe ostentation of property ; good health for instance,and the ability to play a game with graceful ease andcare -free agility.

And that I admit is one of my human failings inreference to cycling.. I think I can do these things aswell as most people of my years, and I certainly obtaina full measure of satisfaction from the process. There-fore, to those who have recently returned to cyclingor taken to this mode of travel as a preservation oftheir freedom of movement, I would say that this isa manly game, worthy of respect as such, and certainlyworthy of achieving a distinction in the method of

,playing it because of the rewards in health and beautythat lie within its dominion. That is not an exaggera-tion ; it is a fact so easily proven if people would onlyallow themselves a trifle of time and trouble to resist

that' innate idleness- or carelessness ofthe slovenly cyclist. I mean what Isay: Half the folk who ride bicyclesare slovenly--middle-foot pedalling,awkwardly seated, handlebars likeplough handles and a swaying, jerkingbody to overcome the slightest hill.You, to whom this paragraph isaddressed, would not, dream of walkingin such slip -shod fashion. Then letcycling do for you what is has done forthousands like me, presented a simplepleasure in the -travel world ofincomparable joy.

The Real TestQOME of you may ndt believe me4-1' when I write in this strain, butthen that is because you have not givencycling the same degree of attentionin the matter of stylist activity thatyou give to other games, such as cricket,football, golf or tennis. Cycling is soeasily. acquired that numerous folk thinkit is Just a question of balance, a trifleof road sense, and foot pressure. Believeme it is much more than that : it isthe correct adjtistment of the body tothe bicycle, or vice versa, the right useof ankles and legs and arms, the nicejudgment of speed to conserve effort sothat a day's journey shall be pleasurablealong every furlong, and, by no meansthe least of all, the elements that go tomake cycling the perfect expression ofactive travel-the right selection ofcompanionship. To think you canbecome a happy, care -free rider by themere possession of the machine is aswrong as is the attitude of a man ormaid who imagine they are golfersbecause they own afew clubs. Actuallyit is this fact that so many millions ofpeople can ride bicycles that makes theart of cycling so difficult to acquire.Of course you can ride; it is a littledifficult to find folk of even mygeneration who cannot; but how far, andwith what pleasure ? Cycling, likewalking or football, can be very hardand wearing if you treat it alviays

as a means to an end, and not in itself worth while.But give yourself a chance to make it a game in whichyou are an expert player, and the Miles you travel arethen invested with a delight, a freedom, and a fascinationthat knows no compeer. I say this deliberately towardsthe end of a life which in its leisure hours has playedmost games and found unalloyed joy in them ; butalways the background of that leisure has been thewide freedom and the ever varying splendour thathas come tchne as a result of my wheeling activities.

Fewer Cycle MakersTHE constant drain of man -power from non -war

industries to the services and the munitionfactories has affected the workers in the cycle trade tosuch an extent that I gravely doubt if the numbersnow engaged in the industry are more than 5,Ooo, andmost of them are well beyond military age. Yet thepowers -that -be are still seeking to discover how manyemployees in the cycle trade can be-in their view-more usefully working in munitions. For myself, I havealways held the opinion that the making of new machinesto replace wastage, and the repair and upkeep of thosein -being, was as vital to our war needs as the retention ofpublic transport ; indeed, that it is public transport atthe cheapest possible rate, and the greatest possibleconvenience. Recently, I understand, the heads of thedepartment investigating the man -power situationworking in non -munition making trades held a meetingwith the industry, the upshot of which appears to havebeen that the Union, representing the trade,' has beenasked to submit proposals with the purpose of still

further standardising the wartime machine, and soconcentrating conditions that the least available numberof employees shall be engaged to produce an agreedoutput of new machines, and sufficient spares to keepthe bicycles now on the road in running order. Fromwhat I can gather, it would seem that authority recognisesthe need for the bicycle and the importance it is playingin transport, and is prepared to leave to the trade theframing of a scheme which will fulfil the need for newmachines and the upkeep of old ones, and still releasea percentage of cycle -building labour for work onmunitions. Provided the labour situation does notreduce the output of bicycles and spares below theneeded minimum for the supply of war workers, onehas no quarrel with this intention, but if the legitimatedemand of the cycling workers is not met, there willsurely be trouble, and far more man -power hours lostto munitions than will be added to the war effort ifcycle mechanical labour is recklessly withdrawn fromthe trade.

Standardisation Destroys InterestTHERE is little doubt that wartime bicycles will be

more and more restricted in specification>, butalready they have reached such a point in that matter,so that further standardisation will make little difference.Some makers I have talked with on this subject seem to -

"think that, pre-war, there were far too many models,patterns 'and fancies; but I -am in no mood to agreewith that dictum, for is it not true that our polyglot ofsizes, and patterns, and types and styles has enabledmany thousand bicycles to be put into commissionbecause the manufacturer could substitute, and wasnot held up for standard stuff ? I think so, from thelittle I know of the problems makers have faced andovercome. Nor should I like to be made to ride abicycle exactly of the pattern possessed by my neighbour ;and that desire to be different, if only by a trifle, isshared by thousands of others. That we must acceptstandard patterns now that the greatest output isessential and labour and materials are limited, goeswithout saying; but I should not like to see such ahabit spilling over into peacetime. One thing I wouldask of the trade is that they keep gearing on the lowside-bolo. for women and 63in. for men as a maximum-bold to 26 x rm rims and tyres, and fit a decentlycomfortable saddle. To me those things are imperativeif cycling is to he made easy for the multitude, and that,I take it, should be the first objective of the maker.

The Old StoryLET me end these monthly notes in a own of praise

for the biCycle and all it connotes in the schemeof quiet pleasure and diversity of interest in these wardays. I. know itis an old story, but it is also a verytrue one, and if you could read some of my correspond-ence you would come to realise how much the quietenjoyment of cycling means to many ordinary people.The cyclist has no pertinent questions to answer as towhy he must travel, he is just a law unto himself duringhis leisure hours, free to come and go as he wills,involving no one in his service, nor interfering with the"lawful occasions " of the community in any way.He and the walker are the only folk left who accord withthe restrictions of the times, and are still free to travel,and the favour of wide horizons is certainly with thecyclist. These things are worth cogitating with springin the air, and the possibility of a short break fromwork in the offing. To start off from your own doorstepone day with a map in your pocket and the " colouredcounties " around you is an adventure of discoverytesting your own energy and aptitude to make a holidayout of the simplest elements, and by reason of that verysimplicity make it the more enjoyable. There is noexaggeration in that statement: all you need is thebicycle, good health and an easy sense of fitness, somefood in your bag and the mentality to travel as the moodof the moment moves you: then the day. or the weekis your own, the sunshine, the wind and the shower,and the very land through which you travel. That isthe spirit of cycle touring, the greatest gift the bicyclecan give you, and it is waiting for you to take it amidthe glory that is an English spring.

- Club Notes .

Manchester ChangeABAMFORTH and K. Redford have changed

their club, and will in future ride for the PyramidRoad Club instead of the Altrincham Havens C.C.

Craig in North Africa" VREDDY" CRAIG, former time trials secretary of

A the West of Scotland T.T.A. and the GlasgowUnited -C.C., is at present serving in North Africawith the R.A.F.

Morrison-Flight Engineer"DONALD MORRISON, hero of pre-war massed -

start events and a member of the i939 World'sChampionship team, has now completed 25 operationalflights over enemy territory. He is a flight engineerin the R.A.F.

Clydeside's 1943 ProgrammeTHE West of Scotland T.T.A. has approved of a

1943 programme, which includes rs 25's, eight5o's and two too's.

Greenock Stars MarryTWO of Greenock's leading cyclists, A. Crichton

and Miss N. Montgomery, were recently married.Both did well in pre-war time trials,

Cozens in ScotlandSID COZENS, prominent pre-war trackman, is now

serving with a unit of the R.A.F. in a remotecorner of Scotland.

Albert Wright in DieppeALBERT WRIGHT, formerly an enthusiastic

official of the Cyclists' Touring Club, ManchesterD.A., and its Rochdale Section, is now serving withAllied landing craft. He was in the Dieppe, raid, aswell as the North African landings.

Starting PromptlyTHE Scottish Amateur C.A. has informed clubs and

associations promoting opens that these muststart at the stated times.

Martin Marries" TOCK" MARTIN, former Douglas C.C. time

trialist, regarded as the " veteran " of Scottishcompetitive cycling, has just married. He is servingin the Army as a sergeant.

New Roller StarT the Douglas C.C. roller contest, held near

" Glasgov., a new star in the person of A. Lindsey,Greenock Wheelers, was pronunent. He won thehalf -mile with 3.51.;5 secs., but was beaten by a Douglasman, J. Macrae, in the flying quarter.


54 THE CYCLIST April, 1943

Cycle tyres ' keep at it ' longer when kept

hard. Under -inflation ruins them before their

time, and is the direct cause of 99% premature

failures. Today, every cycle tyre must give the

greatest possible mileage. Repairs, however

small, must be effected immediately. Every particle

of rubber in Britain is precious. Look after it.

DUNLOP CYCLE TYRES2H/321

/ KEEP THEM HardAND YOU'LL KEEP THEM LONGER ! 7

REMEMBER

THIS HILL?When you are negotiating hillslike Winnat's Pass, Derbyshire,you have greater confidence ifyour brakes are fitted withFerodo All - weather Blocks.Sure -gripping, noiseless in actionand long lasting, they assurepositive yet smooth retarda-tion in all weathers wet or dry.On hills like this . . .



'F-rtV't,"-s7c -A,

St May the Virgin Adderlaury (<3 ma.)F Striae.

Does this Follow ?'THE Birmingham City Coroner stated last monthA that " motorists privileged to get petrol nowadaysare under a strong obligation to avoid running intopeople, especially in the black -out." The connectionbetween the two points is not readily discernible, butone presumes that, when petrol restrictions are removed,.this irksome obligation to avoid killing or maimingpeople-" especially in the blackout "-will be setaside. That follows, doesn't it ?

Merely SillyFOLLOWING the " try -on " policy of shifting the

onus to the victims of " accidents "-the classicexample, of course, is the rear illumination of cyclists-the East Suffolk Standing Joint Committee haverequested' the Home Secretary to make it an offencefor any pedestrian to go out at night without wearing awhite article on his clothing. This is merely silly, andwill cause our Suffolk friends to earn the qualificationusually (and wrongly) applied to therm But theprecious idea is quite in keeping with the present trendof affairs, under which motorists claim a right to gowhere they cannot see. If magistrates would but applyadequate punishment to those who kill and maim,they would be using the proper remedy for " accidents."The illumination of the victims of careless driving,whether through the medium of " white articles,"red lamps, or phospherescent kippers, is the wrongremedy.

',We cannot agree with these conclusions. Cyclists also"claim the right to go where they cannot see," and so dopedestrians. The fact that they pay for claiming theright does not make the other man wrong.-ED.]

DiscoveryTS it possible to take a bicycle through a revolving

door, without' folding back one or more of theHaps ? A fortnight or so ago I would have answeredthis question in the negative, but I now know better.Having a meeting to attend in the city, my bicycleconveyed me thither (part of my plan of leaving publictransport to those who are not so favourably placed),and then I found a revolving door staring me in theface. It was impossible to leave my bicycle in the busystreet, if only because, in Birmingham, there are certainpeople who don't know the difference between meantand tuum-they would steal the skin off a rice -pudding !-and, as " desperate diseases require desperateremedies," I up -ended the machine, inserted it (andmyself) in the compartment, and slowly did the pro-pelling act, with the result that I successfully' arrivedon the other side of an apparently unsurmountablebarrier. At the end of the meeting I repeated theperformance in the reverse direction, and rode home,profoundly satisfied with my great discovery, whichputs old -man Newton and his apple completely in theshade ! .

Further Afield'TAKING advantage of a recent 'full moon, I obtained

a deputy for, my Sunday duties and resumedtemporary indulgence in the week -end habit. Apartfrom the sheer delight to be obtained from this aspectof cycling, I was desirous of examining traffic conditionsbeyond the radius to which my wheeling activities arenow normally restricted, and of seeing what is happeningin the way of prices. My tours last year revealed thatcycling holidays were a shade more expensive than inpre-war days --not surprising, is it ?-and this particularweek -end,- which included a tea at the absurd price of

muleted.rne in so per cent. extra on 1939 figures,Which, when you come to think of it, is not unreason-able. At any rate, I was perfectly satisfied.

As to the other point mentioned, I discovered, aswas to be etpected, that the further I went frompopulated centres, the greater the freedom from triiffic.There were 'long stretches of road-main road,too-without any other' occupant. The Five -MileDrive, op the roof of the Cotswolds, and the "old"Oxford Road, for example, were practically empty.I loitered for some minutes at that point where the

WO, ee/fl4 ,itz i %;).

My Pointof View

bY WAY PAR E 12." zy: ,dr 4

latter road intersects the Fosse Way, andnot a thing was in sight, tct,the dismay ofan airman, who wanted a lift to a certaincamp a few miles away. Broadway andStratford -on -Avon, usually infested at week-ends with motor traffic, were pleasantlydesolate. On the Saturday night I sleptin a Gloucestershire cottage which standsplumb oh a main road. Normally, it wouldhave been a case of " phut -phut -phut,"accompanied by a blaze of lights invadingone's bedroom, but the traffic, after .dark,was less, if possible, than in the day -time.

What times these are for us, to be sure Wise is thecyclist who is able and willing to make the most ofconditions which none of us will probably ever seeagain, when once this war is finished. And what agolden opportunity those conditions present to the typeof cyclist who is nervous in traffic. There is practicallyno traffic to be nervous in One and all, we should take

full toll of these halcyon days, which provide us withthe traffic conditions of 40-5o years ago, plus perfectroads.

Catering ProblemsANOTHER point which struck me, during the

week -end may be worthy of mention-the varyingattitude of caterers towards the problems confrontingthem in these war days. Some of our friends " threwin their hand " at the very outset. Others gave thething a trial before deciding to " pack." A third `classis nobly carrying on, despite the difficulties which arcimposed upon them in the way of official regulationsand interference. At one house where I had tea, thecakes were of pre-war vintage, 'Made with real eggs.At another house, which provided me with as snack,the cakes were in the same class. At the farm whereI had dinner on the Sunday, there was no sign of thewar, either in the array of food, or in the price charged.Thus, with a bit of luck, and if you " know the ropes,"it is possible to fare very well indeed.

Almost Remarkable !TN the House of Commons, recently, the Colonial

Secretary spoke in glowing terms of Malta'ssuccessful resistance to Nazi brutality, wfiich latterarises, I gather, out of a superabundance of " kultur."He mentioned, in particular, the Governor and Com-mander -in -Chief (Lord Gort) " who in a few monthsbecame an almost legendary figure, bicycling all overthe island with his aide-de-camp pursuing behind."It would have been almost remarkable had the A.D.C.pursued his boss from 'some other position !

Aiming HighTN a recent month, says The Times, 29 per cent. ofA. bus failures in the Glasgow Corporation Transportarose from tyre trouble caused by broken glass. 'Thebrainless idiots who think it clever to strew our streetswith glass are certainly aiming high.

Notes of a HighwaymanBy LEONARD ELLIS

Discoveries . Among the RuinsT SOMETIMES wonder during this wholesaleA destruction of parts of many of our old townswhether we shall hear of any thrilling " discoveries."By that I mean when theanything be unearthed that has lain hidden for'centuries ? We all know the curious curve of values inold stuff. When a thing is old-fashioned it is probablyuseless-when it is ancient it becomes priceless. It iseasy therefore to understand, and should not causewonder, why certain gems of architecture have beendiscovered walled up and neglected. They were probablymercifully covered up when they got old and shabby,and at the time no one realised that by thus preservingthem they were storing up treasures for posterity.

well-known example is the wonderful Saxon Chapelnow in full view at Bradford -on -Avon. We can assumethat long ago it fell into disrepair, became an eyesorebefore it was " antique," and was so well covered thatits very existence was completely forgotten, and noteven suspected. Many of the old historians overlook itin their records, proving that they had no knowledge ofits existence and presumably no one in Bradford knewwhat a gem lay hidden. Its discovery was due to thefact that the town of Bradford is built in a sauceror a pudding -basin, with houses rising in terraces all,round. Some 8o years ago the Vicar of Bradford wasgazing over the roofs of his parishioners' houses, andwas struck by somethingcurious=something thatlooked to him like theroof of a church. Consult-ing old records he foundthat Soo years ago nobodyknew of such a church.After much bargainingand wire -pulling this gem,the most complete SaxonChurch in England, wasdisentangled from themass of sordid bricks andmortar that surroundedand choked it. 'To -day itstands proudly clear forall to see and admire, andthere are few who fail toappreciate its beautifulsimplicity and its excellentcondition after nearly athousand years of exist-ence. Its swallowing -uphad been complete andignoble. The chancel hadbecome a cottage, thenave was a school. Asmall house had beenbuilt against an outerwall -. for she school-master, and - a -factorywas built against anotherwall.

The Other Side of the PictureThere is, of course, the other side to consider-. There

are places that seem to offer, great promise, but afterthe expenditure of much time, money and energy theexplorers turn away sadder and no wiser men. It ispossible that Silbury Hill, also in Wiltshire, can beregarded in this category. ,It is generally agreed thatthis mound -is about 4,0o0 years old, and that it formspart of a vast but uncomprehended, plan embracingAvebury and many other relics in the neighbourhood.The hill is said to cover five acres, and that thecircumference at the foot is nearly 1,7ooft. It is agreedthat the builders were faced with a colossal task, as theyhad no machinery with which to excavate and only themost primitive tools. No doubt there was purpose intheir work ; at any rate, the hill stands to -day as amomument to their skill and enterprise, and who knowswhat else. 'There have been many theories wovenaround Silbury, the English pyramid. There havebeen many attempts to explore the interior and to dragaway its secrets, but all the efforts brought little success,and the seekers after knowledge came away with littlemore than when they started. From the dozen or soshafts from side and top have emerged the skeleton of aman, a- piece of timber from the very centre, a -Romancoin, and in nearly all cases the bones of deer and oxen.It is supposed that these latter were the picks andshovels of the builders.

Saxon church, Bradford -on -Avon.


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The Free Guide also gives particulars of ourextensive range of modern Building and StructuralCourses, Building Draughtsmanship, etc. Thegreat post-war Building programme offers un-limited prospects to technically trained men.

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NEARLY SIXTY YEARS OFCONTINUOUS SUCCESS

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Write now for yourcopy of this remarkablepublication,A.M.I.E.E., A.M.I.Mech.E.,A.M.Brit.I.R.E., A.M.I.P.E.,A.M.I.C.E.,A.M.I.A.E., A.F.R.Ae.S.,A.M.I.S.E M.R.San.I.,London B.Sc., Degrees.Fully guaranteed postal courses forall the above and many otherexaminations. Fully described inthe Free Guide.

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