J O U R N A L Olr

THE F R A N K L I N I N S T I T U T E OF TI tE 8"I':VI'E OF P E N N S Y L V A N I A

]FOR T | l g

]I0,[0I[0_N OF THE [ECILkNIC A RTS.

F E B R U A P ~ y , I S ~ .

C I V I L E N G I N E E R I N G .

Extract fJ'om tile Re?oft of the General Board of Health respecting the 3letropol.is.-- Water Sul)ply and Drainage of Towns.*

Continued from page 6.

Professor Way was asked: "For the collection of the rain-fall of a given district, what soil would you prefer?" " I should say, decidedly, a sand. Rain-water, when collected at a distance from towns, is fit for every purpose. All that is required from the collecting surface in this case is, that it shall perfbrm its office without imparting to the water any~ firing to render it impure. Sands which have been washed by rain for ages are most likely to fulfil this condition, and would possess the further adrantage of allowing the ready escape and collection of the water."

Specimens of surface-water collected at various points in districtssur- rounding London were examined; amongst these was a specimen from' the Ruislip lteservoir, the water from which is used for fee " . : Junction Canal; this water is 1?ore the surface-drains e ~ingratbce Grand !.and, a nd."g, ves 8 degrees of hardness, or just one-ha~the im~u~t~ffrC/o ay hme of all the rest of the Company's specimens put together d-. " J •

The searches made south-west of the metropolis appear~ however, from the na!ure of the strata, to be attended with the greatest promise of suc- cess . ~ e evidence2fMr. Donahlson isgiven at length respeetin Rich mona t ark as a garnering-ground, as "th!s one plot of Iand is illugtrative of the principle of improved " ,, ' " . . . . . supphes, lhe soft of,that hark ~,; . . . . . ~1.. or graveuy loam, recumbent on a elavsubsoil '~ 'l,h,, ~,dZ._-~ "Y o 7.2,,~ r

,j - . L ~ r . a t c r t ~ r a l n e a I r o m . it was "perfectly dear, soft to the feeling, well a~rated, and pleasant to;;

" From the London Mechanic's Magazine, for September, 1851. VoL. XXIIf.~' l ' t lxrt~ S ~ n I ~ . ~ N o , 2 . ~ F ~ a v ~ n r , 1852. 7

74 Civil Engineering.

drink." Mr. Donaldson said, in his evidence, " I am, f rom long observa. tion, aware that water passing through a bed of vegeta t ion does leave behind) not only the matter in mechanical suspension, but much of the matter m" chenneal" solution. This is a point which h a s not hitherto re- ceived the attention which its importance deserves. I a m quite sure that a bed of vegetation will detain fbr its food saline and o t h e r matter in solu- tion, which no sand or other artificial filter will separate fi'om the water. I have seen x~-ater containing a considerable quantity o f sewage from a farm-yard, which has passed upon well-drained p a s t u r e land, and the walerwhich h~.s drained through it, has come out perfectly clear from the manure in solution."

"It is to be presumed, however, that there might be an extent of ma- nuri;~g, or shallowness of the filter bed of earth, wh ich 'would not detain the matter in solution? No doubt of it." Animaleu]m have never been met with by Mr. ])onaldson in shallow spring-water as i t came from the spring or drain.

The ordinary rain-fall at Richmond Park is estimated at 25 inches; the usual calculation of the quantity of water collected f r o m rain-fall is the third of the amount of fall.

The Board has in review various sites in the vicinity of the metropolis which might be applicable as gathering-grounds, bu t give a preference to the tract "eommencingwith Bagshot and Woking sands , and extending to Hampshire." t?arnham has been for some time suppl ied with soft water by the drainage of less than two acres of the common land. ' the water 'qs delivered clear and limpid at all times of the y e a r . >~ "There is no reason why the same quantity of water should not be obtained fi'om the whole of a tract of' waste land there, ten miles long and f ive broad." "The improvement of most of these tracts has hitherto been g i v e n up in despair, and lhe growth of fir is recommended as the only agricultural purpose for which they are fitted." The Bagshot sands are es t imated as covering an area of 300 square miles. "Beneath these sands is a retentive stratum of marl and etay, varying from five to fifteen or twenty feet in thickness."

"The portion of this district to which our attention h a s been more im- mediately directed, comprises an area of no less than 100 square miles, lying east and west of a line from Bagshot to Farnham. ~ "Waters col- lected in this district at the surface, immediately after rain-fall, are of the highest degree af purity, being in large quantities not exceeding one de- gree of hardness."

"The chief practical result deducible from these observations is, that by arrangements for collecting the water before it has traversed any great extent or" surf,~ee, a quantity sufficient, as it appears, for the domestic supply of the whole metropolis will be obtainable at a very high degree of purity, prohahly equal to the present supply of l ? a r n h a m . "

"The nature of' the source requires a preservation of t h e rain during pe- riods of" its maximum fall, for a regulation of the s u p p l y during periods of a minimum fifll. The storage-room must therefore b e very extensive. The primary engineerins disadvantages of this district a re , that it nresents no deep natura ~ollows, such as are available to m a n y of the northern to.a ns,:for the storage of water without extensive excavat ions. Here the ex;avations for storage reservoirs must be very l a r g e and extensive.

T]~e Water Supl)ly and Drainage of Towns. 75

Against the modern engineering practice of exposed and open reservoirs, we would rather revert to the custom of' the Roman engineers, and re- commend covering tile service reservoirs and aqueducts to the utmost extent practicable.."

":ks a tbundation for proximale estimates, plans have been got out by ot.r engineering inspectors t'or extensive eovered reservoirs, anti for the conveyance of tile water in dc'ep conduits, also covered. They estimate the total expense of" storing aml bringing to the metropolis this next', and improved supply, inclusive of reasonable compensation for waste land tbr reservoirs, at littI~e more than one million sterling. We fully believe that two years' savil~g from the use of the purer water~ would fully repa2~ this~t)ortion of the outla)."

'Phe Board evidently give a preference to the obtainment of wa te r fror~ suitable gathering-grounds, which, on account of its softness and purity: ~hey consider as superior to that fl'om the souree$ of supply indicated b} C~@ain Veiteh. This genlleman's evidence is, however, given at lengtl~ in Appendix, No. 2. It appears by that evidence that he indicated sere. ral dil-ibrent available sources of supply, and he recommended them or ~ceount of their perennial abundance, "considering that the population o the metropolis has nearly doubled itself in 45 years," "and tha t grea soli~:itude is entertained lest the same rate of increase may continue t( t890, I consider it a most important measure to secure all the bes t sup pli~':~ of water that can be obtained near London, before they be appro t)riated ~o other objects of minor importance. '~ The sources partieularl 2 ~mrelted to are as follows: th(ose at I!ertlbrd, where "there is a singula: meeting of ibm' copious streams of water proceeding fi'om chalk valleys x'iz : ~he Lea, the \'er~llam, the Beane, and the Rib, which jointI:y haw a discharge of ¢9,~t)0,(J00" . . . . . cubic feet~ per die,n;" "the Ash, the Stort , an( springs which join the river Lea below Ware, about 43"20 cubic feet o w.,.ter per day. Such are the resources of the river Lea and its tributaries and which tbr the paramount object of supplying the increasing popula lic)a of tile metropolis with so needful an element of health and consump don ought to be held sacred tbr that pro'pose alone." The conjoint ~vater of' the river Lea, at l,'iehl's Weir, "amount to fourteen millions and a hal of" cubic feet, or ninety-four and a quarter millions of gallons per day? In respect to other sources, Cai~tain Veitch said, " I conceive~ in the firs place, that the water of the river Verulam is the first to be seeured, ant rendered available tbr the public good at London; the water of this rive taken a little above Ve~atlbrd, is a never-failing stream, derived frorr sprihgs, and ¢ielding three millions of cubic feet of water per diem, at a~ altitude of 158 feet above high water in the Thames." "Sirhitar to th( supplies of. water on the north-east of London, which unite to constitut~ the river Lea, fllose on the north-west of London unite to~constitme th~ river Colne, and consist or" the tblJowing streams: The Colne proper, m insignifleant brook in dry weather:" The "Verulam, a.fine s t reanl ," i chiefly fed from springs, and is cleat" and constant, with an average yieh of about 3,000,000 cubic feet per diem: The Gade, chiefly fed by sprin~,, yields a st pply of about 4,000,000 cubic feet per diem : rhe Chess, lime stream fed by springs, "2,000,000 feet per diem. The above stream

76 Ciz, il Engineering.

have their water unitM a little way above Rickmansworth." The river Mole is only noticed as a p robab le source that may be available.

For the supply of ",'cater t o the south side of the Thames, Captain Veitch had "especially d i r e c t e d his attention to the waters of the river Darentla, ~' which yiehl a b o u t ~,600,000 cubic feet per diem?' "The waters above speclfied~ ~ m a y all be dchvered to reservoirs, 140 feet above high water mark. Capta in Veitch was asked, "Do you not con- sider the above quantity of w a t e r as unnecessarily great? If water can be brought to London from such short distances, and at such an altitude on the gravitation system a lone , cool and clear in quality, I do not consider tha(any quantity of such w a t e r , and under such conditions, can be deem- ed over abundant tor t h e hea l th of the population." The supply of water to Rome, under the ]Empire, "'by tile Roman aqueducts, amounted1 to about 50,000,000 cubic feet p e r day, for the use of a population presumed to have consisted of about 1,OOO,000." The population of London is now about two millions anti, a cluarter; Captain Veitch conceives that forty years hence it may be i n c r e a s e d to 4,000,000 of souls.

A statement of all the s c h e m e s that have been proposed for the~supply of water to the metropolis has been drawn up by Mr. Henry Austin, and is published in the Append ix , 2No. 2, of the Board's Report; but as they are all of them variations only of the principal schemes, following up the Board's recommendation of gathering grounds, or deep wells, or Captain Veitch's, to take advantage o f existing springs and streams, it seems su- perfluous in this abstract to e n t e r into particulars of these nfinor schemes.

As to deep wells, it i s abundantly proved that they could not afford a sufficient supply. Whether to prefer the collecting of water from gather- ing grounds, preserving ie p u r e in covered reservoirs, or whether the bringing water impregnated w i t h lime from streams affording a perennial supply, and providing f o r the ptirifieation from lime of the water before delivery, seems mainly a quest ion of pounds, shillings, and pence. The greatest expense attendant on the former mode seems to arise h'om the im- mensity of reservoir requ i r e d ~ t h a t reservoir necessarily a covered or, e; for it is admitted, that in an ot)en reservoir the water would become even more contaminated with oNanie impurities, animal and vegetable, than it is found to be even in the " l 'hames . These reservoirs would have to provide not only for a sufficient s u p p l y during the dry weather of ordinary sum- mers, but also for seasons of extraordinary drought; the leaving London so much as a single d a y wi thou t water, is too horrible a chance to be risked. There are some seasons when, for perhaps two months, there is :no material rain-fall. Kov~ l n a n y acres of covered reservoi~ would sutfiee for.the supply of London during, such a drought? It is easy of calculation; so is the expense of depr iv ing water of lime, which wouht be to be com- pared with the cost of c o v e r e d reservoirs. The depriving water of car- bonate of lime, by Professor Clark 's process, might perhaps suffiee~fur- ther purifying it in Mr. la lol land 's mode would add to the expense; but even that is compensated for, according to his evidence, by enabling thus the water to save soap in "washir, g, and to require less tea, &c., in making extracts.

Should the gathering g r o u n d system be adopted, Professor Way's ex- perimen% in addition to exper ience at Farnham, and to general agricul-

The Water S~tpl)ly and Drainage of Towns. 77

rural and other observations, indicate that the gathering grounds should be under the complete control of whatever person or persons may have- to govern the supply of water to Luadon; this would be essential, since those grounds should at all times be kept at a certain degree of vegetable production; enough of that growth to assimilate the whole of whatever adventitious manure might fall upon the grounds, as also any moderate quantity that might be permitted tbr the purpose of profitable cultigation of tile area chosen as a gathering ground.

The propertk's desirable in water itself" having been thus exhibi'ted; mid the sources t)om which a supply may be obtained, the next considera- tioa is that of th(? most efficient anti most economical mode of bringing water to the metropolis, and of distributing it therein with the greatest convenience and at tile smallest cost to the inhabitants.

'l'Ite General Board of Hc;dth are of opinion, that "even if the same sources of supply as those !aken tbr lhe New River were eligible, and if tl,.r).~e works belonged to the public, they ought to be abandoned, arid the t?.oman principle of covered channels reverted to, as Captain Veitch pro-: poses."

Captain Veitch, in his evidence, gave r~any partieuNrs,.showing that l}~e mode origlnally adopted for the conduction of the New River was dt~fective, on account of its bein~ an often canal followinff all the sinuo-. , J a ' ~ "

sities of the grouM, as on a contour line; that it had an inclination o£ <~nlyo three inches per mile, but that "within the present eentur, y~.ff.reat in- geauity and great expense have been applied by the New River Company to correct the evils of the rude and vicious mode of conduit first adopt-. ed." He observed, that "a great ob.i':'cdon to the conveyance of water for domestic purposes, ira an open earthen channel, is, that the water must have a very slow rnotion~ not exceeding half a mile per hotlr, to prevent~ the eurren.t wearing the chanmd-bed, and bringing in turbid water; the slow motion is again attended, with serious evils, depositions of silt and decayed vegetable 1hatter take place, which require to be cleaned o~t fi'om time to time; in the warm season, so long and broad a surface ex- posed to the atmosphere gels heated to a degree favorable to the produc-. tion of vegetable and animal life of the lower tbrms, and also in giving rise to a consTderabte quantity of waste from evaporation; the high tern- perature of the water rather taeilitates the decoction of leaves and other- vegetable matters, which get btowrr in.to the New River, to the manifesV i~jury of the water; but there are other pollutions of a worse character,. to which all open canals are subject. It is true, the New River C0inpany have five acres of settling-grounds at Clerkenwell,* and thirty-eight a t Newington, for the dep.o~t of solid matters." "S~eh are the i~b'eetions:,j. . to all open water conduits conducted in earthen ehannels~ the.defic~enews. of which will,, however, be still, better appreciated by u contrast with ihe qualifications that may be obtained for the same water, if conveyed in

* Dead dogs and cats arc strained off by a grating before the water, enters the settling ground at the New River l:Iead, but other impurities cannot be so separated., A panic h a s sometimes been occasioned by a report that the New Rive~ was poisoned; as it happened during the excitement occasioned] by Lord (~eorge Gordon's riots; all the ~rater was t hen tbr a short time red; this, on cxamination~ was found to liar6 ariien:from a quantity of re-.. fuse madder, throwa in f r o m a dye-house.

7*

78 Civil .Engineering.

covered channels constructed of st(>ne or brickwork, and conducted in straight lines, with an uniform and efficient descent, crossing valleys on embankments or arcades, and piercing hills, by tunnels or adits; for ex- ample, the water of the river Lea might be conducted to London in such a channel fl'om Ware, at a distance of 20 miles, instead of forty, and with a speed of one mile per hour, instead of half a mile; that is, the transit would be accomplished in twenty hours instead of eighty."

Mr. Rawlinson, in giving an aceount of the Croton aqueduct, instanced it as serving both as a warning and an example. The aqueduct itself has cost upwards of 40,000/. a mile, exclusively of reservoirs; it is supported upon a solid foundation wall, 17 feet thick; the "true aqueduct or water- way is constructed wifl~ a brick lining upon a c~nerete foundatmn. The whole s~rueture is banked up with eartl~ on each side. "I t would be diffi- cult to devise a more expensive work." "Nevertheless, in several in- stances, it has been found necessary to line the water-way with i ron."

Mr. Rawlinson is of opinion that "iron, wrought and cast, may be much more extensively employed in water-works than has hitherto been the practice." "Where it is not thought advisable to cross a valley or river by ,n inverted s:yphon-plpe, an elevated wrought iron tube aqueduct may be constructed, light, elegant, nay, even gracefifl in structure." "Telford set an example in his celebrated Pont-y-Cypoytte aqueduct, which is 126 fee~ in height, 1007 feet in length, and has a cast iron water° vcay as sound and perfect now es the day it was made."

iVh.. tlawlinson himself, in 1846, proposed a plan to the Corporation of Liverpool to bring in a supply of water from the river Dee. "The several intermediate valleys would have been crossed by inverted syphons, or by means of elevated aqueducts of wrought iron." His proposal was submitted to Mr. Fairbairn, who in his report to the Chairraan of the Liverpool Water-works Committee, October, 1846, said that " tubes 6 feet deep ~nd 2 feet wide, with etose tops, can be made of sufficient strength to carry 33 tons of water on 100 feet span." "The weight of 100 feet of such a tube will be about 12½ tons."

In respect to durability, "care must be taken to prevent oxidation, and in order to do this effectually, it will be necessary to make the top of the tubes, as all the other parts, perfectly water-tight, and the tube being ahvays full of water, it will be a great security against corrosive action la the interior. On the outside the usual preservatives must be applied; • a, ith these precautions, the tube might last for an almost indefinite period of time."

"The effects of winter, or the change of temperature, will not be se- verely felt on a long and somewhat flexible tube. Internally the tempera, turc will not vary considerably, as it never can be above 60°~ and never lower than 320."

Thus it seems that Mr. Fairbalrn is in favor of iron tubes. Mr. Rawlinson appears to advocate economy in public works. H e said

that " I f modern science has taught us how to make a steam engine, it has not yet Nlly inculcated the necessity there is that rigid economy should be studied in all engineering works." He gives the aqueduct 071 Spoletto as an example of the small quantity of masonry that suffices for

The l~ter Supply a~d Drainage of Towns. 79

piers. " . . . . . '1 he middle arch of that structure is 3"28 feet m clear height, sup- ported on piers 10 t~et 6 inches thick." The Pont du Gard, near Nismes~ - I "O' J~rance, might also have been noticed for the small quantity of masonry i~ its piers; in this instance they have occasionally to resist the immense three with which the waters of the Gardon come down suddenly upon the piers after storms in the mountains, converting a shallow brook into an impetuous broad river.

The mode of exectltion the Board prefers is not indicated in their Re- port; but it i:; said that, fi'om proximate plans anti estimates, "got out by our engineering inspectors for extensive covered reservoirs, and for the conveyance of the water in deep conduits, also covered," 'they estimate the "t~tal expense of storing and bringing to the metropolis ~his new and improved st, pply, inclusive of reasonable compensation for waste land for the reservoirs, at little more than one million-sterling." The Board, in their twenty-fifth question to Mr. Stirrat, of Paisley, s n i d e " W e find at present we can cover a reservoir at about 1000l. an acre." Mr. Stirrat had previously observed that, "as to covering or roofing the slor~g'e re- servoirs, that is altogether unnecessary, as nothing of the kind" (the growth of vegetation and production ot:animal litb) "affects us in so deep water." So, in other evidence, it is intimated that where waters are deep, the evils in question do not exist. As to loss by evaporation in uncovered reservoirs, Mr. Stirrat s a id~" I t is a great mistake to imagine that evapo- ration takes place to any extent, even in the height of summer, from the surface of a reservoir, where the water is of any considerable depth. The deposit of dew, I think, counterbalances it. I have one pond 10 feet deep, on which I made the experiment, and found, in the teat of sum- mer, that in two months it did not go down one-sixteenth pa~t of an inch; and there might have been a small escape to account for even that dimi- nution."

Whether on polilical grounds the water-supply of London should be from one single source, or from many diflbrent sources, does not seem to have been adverted to by the Board itself, or by any of their witnesses; nor, though the water were derived all of it from one and the same source, whether it might not be expedient to convey it to town in two or more conduits, rather than by a single aqueduct. That an army of foreign invaders would easily find its way to London, and burn it, is not to be feared; but that attempts to so destroy it, should be made by its own populace, experience has proved, and ~hat in furtherance of this seherae cutting off the water was designed. Had Lord George Gordon's riots lasted another day, the mains at the New River-head would, it was dread- ed, have been cut off, though ~ueh troops as could be spared were order ed for the protection of those x~ orks. It should not be lost sight of that, in all metropolitan disturbances, a great portion of the rioters is made up of those whose object is plunder, and that plunder is facilitated by exten- sire conflagration. Ia that fearful night, when his Lordship's mob had the upper hang, no less than fourteen separate fires were counted from one house-top; and then it was that the abundant supply of water saved the town. Of late, too, when setting fire to houses was one of the projects in an intended insurrection~ the water would doubtIess have been cut off.

80 Jlmerican Patents.

On such accounts, this political question in regard to water-supply seems well worth consideration; and it will be hereafter shown by what arrange- ments water might be conveyed to every part of the town~ th(mgh all but a single conduit were destro)c.d, i\l. S. i3.

Exl)eri'me~ds on l/re ,S'lre~g'/Jl, ( f ]Vrou/4"/~l or Rolled [ro~ ,Ioisls.*

Messrs. Fox and B~rrc~t bare ,j(~st introduced rolled iron joists as a substitute fl)r cast iron in 1he' c(mstrucfion of their tlre proof iloors, de- signed xxi~l~ a view to ruing the expense to l h e same as those o~' cast iron, aim thus render tire l)roof conslruction with ,joists of wro~N'/~t iron as in-

T i / expensive, according lo me r s!atement, as the ordinary timber lIoors. On the 25~1~ Novembc, r, some experiments were made on j~flsts of two

sizes, at the l~ahs and Wash Houses which are now being erected for the parish of St..James~ ia JJufi)ur's Place, Poland Street. The weight was applied d~rough a lever. The following particulars have been flu'- nhhed to us.

't'he smaller of the two joisls w~s .%} inches deep, and ~-in. lt~ick~ uith tlanch top and botlom, 15~ inches wide.

l ,em;th of joist% 17 feet. ~;Vidth of bea~ing, . . . . 16 "

We igh t per ibot :'an, 10 3-5 lbs. W~i~ht i;er sq. ft. of floor which

Load on Centre. Dc~exlon. the load is equivalent to. 12 cwt. .65 112 lb~ per foot. 15 , -80 . 140 ,' 18 1-O0 168~- " 28 . . . 1 . 4 5 . , 26o~: ,,

The larger joist was 7 inches ~ieep~ and ~a-in. thick, with flanch top and bottom, 2~ inches wide.

] ,cm;th of joist, 17 feet. Wid th of bearing, . . . 16 "

~,Yeiglit per tbot ran, 16} lbs. W e i g h t per sq. ft. of floor which

Load on Centre, Deflexion. the load is equivalent to. 12 cwt. %2 112 11/. per ibot. 28 . "785 260 " 3~ .90 300~ ,, 4{) • 1"10 . 370§ "

AMEI~ICAN PATENTS. Lid e¢ Am erlcan Patents whlch issued fi'ora December 9, 1851, to Januar~j 6, 185 o,

(;no/us&e,) wi/h Exempbfications by C ~ t ~ x s M. K ~ L ~ n , l a t e Chief Examiner of Palenl;, in lhe U. S. Palent Qffice.

~1. For an Improved Revolvin¢ Reverberatory Furnace; Ambrose S. Beadleston, Au Sable Forks, 2~'cw Vork, December 9.

t ] ° Lt " ,/a~m.-- W h a t I claim as my invention is, the rolling or revolving furnace revolving on friction wheels or rolIc>,%r their equivalent, in combination wi th an ordinary fire, such as is used in reverberatory furnaces, the two being combined in such a ~nanner that the

From the London Builder, No, 460. Up to this point the elast ici ty of tlm metal was uninjured.

~: Permanent set on removal of load, '075. A load of 18 cwt. on the centre was left on 18 hours, bat produced searco, ly any perceptible difference,

§ Permanent set oa removal of load, ' 0 6 2 .