412 On the comparalive power q/" Sleam.

been done, they feel confident it will be attributed to causes without their control, l'he constant aim of the committee has been, equal justice and impartiality to all. The are aware that many articles, Y . . . . .

deserving special notice, have been mmtted m tins prehmmary re- port. Respecting such they give the assurance, that in a few days~ they will present a detailed report of all which were exhibited~ with their respective merits.

S~ttlMEL V. MEmIIC~ • ffAI~IES RONALDSON~

THOS, FLETe HI~iR, ADAM RAgtAG E, M. W. BALDWIN~ M. D. LEwIs~ ISAIAH LUKI~NS~ CHRISTIAN G0B ltEetrI',

Committee on Premiums and Exhibitions°

Observations on the comparative differeme in the effective power of Steam, as applied to the Rotary, and Reciprocating Engine.

T O T H E ~*'I ) ITOR OF "J~E[B ]~]~ANK.LIN J O U R / q A L ,

SiR,--Having often enquired the difthrence in efihct between a reciprocatin~ engine and a rotary one, without being satisfactorily answered, I ~ately endeavoured to solve the problem myself. I have sent you the result of my labour: should my method of calculation be obscure, and the conclusion erroneous, [ need only put you in nfind, that you have promised to destroy, to correct, or to expunge, with tenderness, the communications of those who are less accus. tomed to handle a pen, than a HAMMER.

A reciprocating steam en- gine, whose cylinder is ~ fhet

0 long and one foot in diameter, wilt describe, by its crank, a circle fl feet in diameter, which will require a double stroke of the piston, and so consume a

¢~ column of steam 4 feet long and one tbot in diameter; but

, 0 the whole power of the steam will only be exerted at two

" ~¢o points in the circle, viz. at A " and B, and as the crank recedes

from these, the power decreas- a es till it reaches C, C, the dead

o points, where the steam is al- ~ 4 ~ together of no avail~ and on

the contrary, as it approaches A, B, the power increases till

~ 4 ~ it arrives at its maximum~ at those places. Now let us sup- pose the circle divided as ir~ C

On the comparative power o f 8team~ ~1 s

tbe diagram, then each figure will express the power of th~ eng~nle at the time tile crank is opposite to it: so, afso, would' }he':!~oss amount of all the figures united, express the powei ~ of tim et4 durin~ one revolution o[ the crank, or a double stroke of the pis2 ton: may we not state it thus?

Power ~00 (the amount of figures)produced bya columri of ste~tu 4 thet by I foot.

Now suppose a rotative engine of the same diameter as the circle which the crank above, deseri6es~ (viz. ~ feet) and the areaof whose piston is the same as the one above-mentioned; then, (leaving i~riction, &c. &e. out of the question) the force of such an en~ine'~vould be the same in all points of the circle, as the reciprocating one at A and B; consequently, each figure would represent 10, and thewh01e united, 400, or "ust double the .ower )rodt~ced b t h e reci rocatin • J 1 ~ 1 Y P g engine.

But then the quantity of steam consumed by the latter, will be considerably more than ihe former, viz. a colmnn of stea,n 6.~83~ the circumference by 1 foot: the account will then stand thus, the

Reciprocating engine, power ~00~ steam 4. Rotary do. power 400, Steam 6.~83~.

then if 6.~85~, the steam cor]sumed in the rotary, produce power 400, what will 4, the steam used in the reciprocating one( pr&luce? the answer is, $54; so that, if this calculation be hot visionary¢ a rotative engine is to a reciprocating one, the quantity of steam corn sumed being equal, as £54 is to ~00, or one-fourth more effective:

New York, October ~1, 18~8.

Remarks by the Editor.~The practical difficulties which have at- tended every plan hitherto attempted for constructing a rotary en- gine~ seem to us to render any comparison between it and the reciprocating, a task of no easy peribrmance. Which of the nume- rous: rotary engines, shall we a~topt, as the subject for comparison? In some of thegn, condensation has been atten]pted~: in otl{ers,;tl~6 high t~ressure principle, without condensation~ l{as beeh essayed;in all o[~ them~ the difficulties of packing, of constructing the va]ves, of letting the steam on and off, &c. &c. are sources of iinmense loss of power. The fact i% that a good rotary engine, or even one whose power can be calculated, is, in our opinion, a mere theoretical being, whilst the reciprocating can be correctly estimated. In a rotary engiue, the steam is never cut off; in the reciprocating, it may, anal ought to be, cut off long before the stroke of the piston is coml)leted , depending upon the elasticity of the steam employed. These are mere hint% but we can give no mor% as the subiect would demand more time anti space, than we have to spare.

414

Remarks on the arlicte zqmn Perpetual Motion, in the last ~uonber of the ~'anklin Journal, by a Corre~TondenL

• S ~ t , ~ I have been much gratified, by the article in yonr Journal tor November, on Perpetual Mot,on, because the inibrmation there given of some of the most plausible schemes tbr producing it~ is, I think~ equally with the demonstration of their futility~ calculated to awake many active and ingenious minds fi'om their day dreams, which, however, if they did not cause much loss of money or valua- ble time in the pursuit of an ignisfatuus, might be an innocen b and not always profitless amusement.

Great cre(ht is often claimed for our countrymen's alleged su- perior ingenuity, and. inventive powers. . I am. not disposed., to dis- pute the claim: it is at once accounted for m the pecuhar circum-

s tances of a new and thinly settled country, where every farmer is urged, by necessity, to contrivance tb,' the supl)ly of constantly re.o eurrmg wants. This evidently conduces to tbrm that character thr acuteness and ingenuity~ among our yeomanry, which would be seL dora tbund on the farms, if in the wo~rkshops, of Europe° l iu t that scientific and practical knowledge of mechanic% which is essential to the invention of a good machin% is equ~dly rare among us. These two causes, both operate to produce, and are manifest in, the multithrious inventions and machines that crowd the shelves, and the records, of the patent office~ and in the inquiry~ why so very few of them~ though new to the patentee, at% in reality, orig;~)al and valua- ble, we shall, probably, lind little to grati/~y ou'r national pride; fiw I believe it must be allowed, that most of them evi:lee a deficiency of mechanical science, or an ignorance of the progress made in it.

I desire not to depreciate the character of our nation %r natural or acquired talent, but to show the need there is for more fall an~I correct information to direct it usefully in the departl~ent of mc. chanies; and I believe the exhibition you have given of the fi~tilc attempts to produce a pe,'petual motion, will be useful as a corrective of the evil I have alluded to, and that it might be profitably extended to other subjects.

But even the pursuit after perpetual motion, hopeles~ as it is. tnay not be considered entirely vain. As an exercise of the mind and of the inveutive facultie% it is not useles% as it may, occasionally~ lead to useful modifications of machinery. As an instance of thi.,;, I here submit to you, a nlan suggested by an ineenious friend o~ mine, several. .yearsag° ' for. l)r°jec°ting lev~rs., fro~l~ the centre and on one side of wheels, winch was new to me, and if so to you, may be considered worth insertion in the Journal, as an appendix to yot~r remarks on perpetual motion.

The diagrams annexed, exhibit the plan. and need little explana. lion.

Remarks on lhe ~qrlide upon Perpetual Motion,

Fig. 1.

415

Fig. 1 is a oeroendicular view A, A. are two vertical whi~els placed diagonally, and revolving on the axes X, X. The levers Or arms 1~, B, and C~ C, are hinged at the peripheries of the wheels, and ave jointed near their cen~tres. By rotation of the wheels, the arms B, B, are projected from tile centre of motion, while tile arms C, (3, are drawn in.

Fig. 2.

t /

i / /

/

It is plain, that a series of arms, as shown in the horizontal View of one of the wheels, Fig. ~, will produce an eccentric motion, causing the weights at their ends, apparently, to preponderate on the side B. It is obvious, also, that a ring attached to the joints of tile arms, would form an eccentric, applicable, perhaps, to some useful mechanical purpose. B~aanoa°

November 15, 1828.

416

Notlce respecti~g Slean~ Carriage,~. i?y lhe F,~)~TO(~o Wl,: have several times ad vetted to the stiSject of steam carriages~

and have ever expressed the opinion that, Ul)~m ordinary road% they will not be made to fulfil the conditions required, for the conveyance of passengers, or the transportation of goods. For the convenient and safe t{pplication of steam power, a degree of uniformity of row. tion is requisite, which we think it impossible to obtain, where there are considerable ascents and descents, stones, ruts, and other ob-

oe " structions. We have inserted f,'om the Eu~hsh Journals~ several notices of attempts to overcome timse ditficulties, and we have con- tinued to seek for all the intelligence that has been published upon the subject; but the articles which have come under our notice, have been so contradictory, that we were only likely to mislead out" read- e,'s by their insertion. Of late, Gurney's steam carriage appears to have taken the lead, in arresting public attention, and some of the journalists have spoken of it as completely successful, whilst others 'have represented it as an experiment alti)gether unpromising in its character. In the London Journal of Arts and Sciences, the editors, Messrs. Newton and Partington~ say, ~ to several inquiries as to the progress of the steam coach, we are compelled to reply~ that there has not yet been any carriage exhibited, either publicly, or rivately, which warrants us in saying that the object is likely to be ePt~?cted. ' ' The proprietors, however, if we credit the representations published by them, or their friends, appear quite confident of success, and, indeed, claim to have already succeeded.

• W e have been presented;, by . . . . Turner Camac~ Esq. of Philadel..l)hia, with a large geometrical drawing of this carrmge, (Gurney's) m plan and section. This drawing was brought over by Lieut. Col. Camac of the British army, a brother to the-first named gentleman. We have conversed with the colonel, who had ridden a considerable dis- tance in Gurney's carriage. This trial coach was sutficiently large to carry six passengers inside; besides thes% there were eight per- sons on the outside'; two of whom were employed in the management of the vehicle, the others were passengers. The general impres-. stuns of Colonel Camac, as regards the coach, are favourable, but he apprehends that the obstructions from rough, or deep roads, and steep ascents, will with difficulty be overcome, although on level and good roads, the travelling was pleasant and rapid.

In public trials of this description~ it is not the wish, nor is it the business, of projectors, to be defeated in what they attempt, and the experiments are~ therefore, made in the most fitvdurable situations, where apparent perfect success is well calculated to lead a very large majority of the spectators into'error; and tliis we apprehend has beel~ the case in the present instan;e.

Much skill has~ of course, been employed in the structure, as it has been long in hand, and under the direction of men of ingenuity, who have profited by their own observations, and tliose of others, as successive difficulties have been encountered. W e do not, however, in the present state of our knowledge, think it necessary to give an

On Colou~ing Engravings , and o n Coloure~, Ink~, 417

i~gvaved representation of" the engine and carriage W h e r ~ i t ~ ~ave carried assenters in s ~ . . . . . . . . . ~" '~ '::~' ~;'? .~ , p ~, , uccess~ve tr~ps, on a rout~:of~:,t:w~t~

roues, wnere the usual varieties of hill and dale must h/i~e be ~ cou~tered, its structure and merits shall' be fully exhibited:,i:

vv e w~tl, at present, briefly remark, that the ~ iwo steam cylinders, which work two cranks on the axle of the hind Wheels, ar~: placed under the fore part of the carriage; the boiler, which is tubular; is in the boot, behind, and is encased in such a way as to radiate but lit. tie heat; there is a tank below the carriage, for containing a supply of water; there are six wheels, the two ~)remost being turned b~ k handle, under the management of the guide, to direct~the carriage, As .a. chimney of sufficient height, to procure the/requisite dr~ft, could not be used, a blower, or fan, with revolving ianes, ia enU ployed° To aid in ascending hills, there are propellers, which'are to operate like poles in propelling a heat; and there is a drag,.oi. brake, to regulate the velocity, in descending.

On Colouring Engraw:ngs, and on Coloured Inks.

TltA/qSLATED F 0 l t T i l e F l t . ~ N K L t ~ JOURNA~L;

[From the Jou~'nal des Connoisance Usuelles. ] Tnr. art of colouring engravings, is very easily acquired, and cat~

be practised by persons who are unacnuainted With drawin~ Oni. so much skill is necessary, in the co~nmencement, as shal~ ~ Suffice ~ for the imitation of good models; and a little practice will then give facility of execution, and improve the taste. As this a r t is very amusing to children, and furnishes an agreeable Occupation to females, we extract from the Encyclopedia Moderne, some direc- tions ~br its performance.

The colouring of hooks of engravings~ and of those which orna- ment the volumes in our libraries, are usually executed b~ ~0m:en~ it consists in giving, by means of tim perlci~, th~V6~ii~ii~h~:!:.~o ' printed engravi~gs, which sliatl correspon~l w~th the native'h~e's of the ob'ects, J re[~resented . . . . Th s art has, in modern times, •ari'ivedat ~reat perfection, as may be seen in various beautiful collections of flowers and plants, which have been presented to us.by those Who have attained the ~oTeatest sk~ll m thxs department. ] 'he maznificent collection of roses by Redout6; the medical Flora of the ~Antilles by D6courtils, and many others, might be cited as examples.

This colourin,, is a kind of bodiless painting, or rather of Washed drawing; the tints employed, ou~,ht to be transparent, and .tht~ those w~hich have the |easel body(are, therefore, chosen~ p( "rather colours. . are preferred, which, are without any, as rinse. Which a r e . . ob~ rained from flowers, and which are tbund to be the mostsmtable [br this kind of work. When it is necessary to take su:di as aloe niOtie ~ross, they are r,;peatedly washed, so as ~ eventually to prOcUre tile liner' particles only.

The blue petals of the iris., afford .'t ,.~-reen" t~cula;', but this,, mw ever, i~ less beautiful than that obtained fi-om the t'ipe berrie!~ of