1839.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



409 



by Ne\rconien's engines. From this time, the use of the new engine 

 extended in the mining districts, particularly in Cornwall ; Boulton and 

 Watt receiving as payment the value of a third of the quantity of coal 

 which each of their engines saved. The commercial importance of this 

 invention may be conceived by one autlientic fact : in the single mine of 

 Chacewater, where three engines were at work, the ])roprietors found it 

 worth while to purchase up the rights of the inventors for an annual sum 

 of 2,400/. Thus, in one single instance, the substitution of the condenser 

 with internal injection had effected a saving of 7,200/. per annum, in the 

 produce of fuel. 



People agree, without difficulty, to pay the rent of a house or a farm ; 

 but tlus feeling ceases when it att'eets an idea, whatever ])rofit or advan- 

 tage it may have procured. Ideas, why they are conceived without 

 laboiu- aiul without trouble ! Besides, who knows but in time, every 

 one would have thought of them! In this way, no days, months, or 

 years can give validity to a privilege. To these opinions, \vhich it is not 

 certainly necessary for me to criticise here, custom has almost given the 

 sanction of a fixed decision. Men of genius and manufacturers of ideas, 

 seem condemned to remain deprived of all material enjoyments ; and, it is 

 very natural,- that their history should continue to resemble a legend of 

 martyrs. Whatever we may think of these remarks, it is certain that 

 the Cornish miners paid from year to year with more repugnance the rent 

 which they owed to the Soho establishment. They took advantage of the 

 first objections started by the plagiarists, to assume that they were dis- 

 charged from all obligation. The question was a serious one : it might 

 have greatly injured the fortune of our colleague, he gave up to it therefore 

 his whole attention and became a legist*. The incidents occurring in the 

 long and expensive suits which Boulton and Watt had to carry on, and 

 which at last they gained, are not now worthy of revival, but as 1 just now 

 quoted Burke an.ong the opponents of the great mechanic, it is but just to 

 remember that on the other hand, the rights of persecuted genius were 

 maintained before the seat of justice by the testimony of Roy, Milne, Her- 

 schel, Ueluc, Ramsden, Robinson, Murdoch, Rennie, Gumming, More, and 

 Southern. Perhaps also we ought to add as a curious trait in the history of 

 the human mind, that the counsel (I shall have the prudence to remark 

 that I am oidy speaking of the counsel of a neighbouring country) to whom 

 malignity imputes a superabundant luxiny of words, reproached Watt, 

 against whom they were employed in great numbers, with having invented 

 only ideas ; this, we may remark, led to the following apostrophe in Court 

 of Mr. Rous, " Do as you like gentlemen, with these untangible combina- 

 tions, as you call Watt's engines, they'll crush you like flies, and blow ^-ou 

 up out ot sight." 



The persecutions sustained by a man of mind, where he has a right to 

 expect, with justice, unanimous expressions of gratitude, seldom fail to dis- 

 courage him, and to give a tone of asperity to his character. AVatt's natu- 

 rally good disposition could not resist such rough attacks ; seven long years 

 of law excited in him a feeling which led hira sometimes to expi'ess himself 

 with bitterness. " W\\at I feai' most," wrote he to a friend, " is piracy. I 

 have ah'eady been cruelly attacked by plagiarists, and if I had not a tolerable 

 memory, theh' impudent assertions would almost have persuaded me that I 

 had never made any improvement in the steam-engine. You would scarcely 

 credit, that the ill-feeling of those whom I have most served, goes to that 

 lenjjth that they maintain that these improvements, far from being worthy of 

 encouragement, are injurious in the extreme to the uation.il wealth." 



AVatt, although greatly UTitated, was not cast down ; his engines, wliich, 

 at fiist, like those of Newcomen, were only mere pumps for draining, in a 

 few years he converted into universal movers, and gave them an indeliuite 

 power. His first attempt was the application of the double-act Inr/ evgine. 



To understand the principle of this, we must refer to the Improved mgine, 

 of which we have abeady spoken at page 407. The cylinder is closed; 

 the access of the external air is cut otf; tlie piston is forced do^^^l by the 

 pressure of the steam, and not by that of the atmosphere ; the rising move- 

 ment is eft'ected by a mere counterpoise, for at the moment, when this action 

 takes place, the steam, circulating freely above and below the cylinder, presses 

 equally on the piston two opposite ways. So that, as every one may see, 

 in the improved engine, as in Newcomen's, there is no real power, except 

 during the descending stroke of the piston. A veiy trifling alteration 

 remedied this serious defect, and gave us the double-acting engine. In the 

 eng;ine known under this name, as in that which we have called the improved 

 engine, the steam of the boiler passes freely to the top of the cyhnder, and 

 forces down the piston without any difficulty, for at the same time, the infe- 

 rior capacity of the cylinder is in conminnication with the condenser. This 

 movement once effected, the steam is cut off from entering above, and is 

 now, by opening a certain cock or valve, admitted to the under side of the 

 piston, and raises it up simidtaneonsly, the communication from the bot- 

 tom of the cylinder with the condenser is closed, and a similar passage is 

 opened from the top of the cylinder to the condenser, and allows the steam 

 to be drawn off from above tlie piston to the condenser, where it becomes 

 liquefied ; when this is done, and the piston anives at the top, all the cocks 

 and valves again change their movements, and are replaced in their original 



• How different is tliis from tlnf pl:iin narration of Stnart, and ttie actual facts. Poor 

 Boitllon ulio liaci the wliole cuniniercial management, for wliich Watt was totally uiitit, 

 is here left entirely out of the qnestiou, in order that M. Araeo may make a point, and 

 add aiiuiher to the long string of miracnioijs qnalilications with which he has endowed' 

 his onhappy confrere. The medicine and surt;ery misht have pased, but what will the 

 gentlemen of Westminster Hall say to this sudden acquirement of a subject for which 

 they lind no l\mv iatiicivnu^ Note uf the Tramlator. 



position. In this way the same effects are reproduced indefinitely. The 

 motor, as has been seen, is here steam exclusively, and the engine, making 

 aUowauce for an inequality depending on the weight of the piston, has the 

 same power whether in ascending or descentUng. On tliat account it was 

 justly called on its first appearance the double impulse engine, or double acting 

 engine. — see Jig. ] I and V2. 



To make his new motor of easy and commodious application. Watt had to 

 conquer other ditficultics. He was obliged to find out the means of establish- 

 ing a rigid communication between the inflexible rod of the piston oscillating 

 in a straight line, and a beam oscillating circularly. The solution which he 

 produced of this important problem, is, perhaps, his most ingenious invention. 

 Among the constituent parts of the steam-engine, you have, no doubt, ob- 

 served an articulated parallelogram, which, at each doidjle stroke, stretches 

 out its sides and coUapses them with the ease, I had almost said the grace, 

 ■nith which the gestures of a perfect actor charm you. Follow the progress 

 of its various transformations progressively with the eye, and you see that 

 they are under sulijection to most curious geometrical laws. You will per- 

 ceive three angles of the parallelogram describing, in space, arcs of a circle ; 

 while theyoMr//(, the angle which raises and lowers the piston rod, moves 

 abnost in a straight line. The immense utihty of the result astonishes me- 

 chanics still less than the simplicity of the means by which Watt effected 

 it.* — see fig. VA and M. 



Power is not the only element of success in manufacturing processes, regu- 

 larity of action is equally essential ; but how can we exjiect regularity from a 

 motor which is engendered from fire by shovelfids of coals, and even from 

 coal of dift'erent qualities, under the superintendence of a single workman, 

 often unintelligent, and almost always inattentive. The disposable steam 

 will be so much the more abundant, and will flow into the cyhnder with 

 greater rapidity, and move the piston so much the faster, as the fire has 

 more intensity. Great inequahties of action seem almost inevitable, and the 

 genius of Watt had to proride for tliis palpable defect. The valves by which 

 steam is discharged from the boiler into the cylinder are not alw.iys open to 

 the same extent ; when the engine is working fast, these valves partially 

 close. A certain quantity of steam must tiierefore require more time to pass 

 through them, and the rapidity is iliminishcd. The openings of the valves, on 



Fig. 12. 



f~^ 



^"^^"^^^^v 



BOULTON AND WATT'S DOUBLE ACTING ENGINE. 

 The parts arc shown in Fig.ll, where C. is the cylinder ; the steam enters 

 at S, and passes into the upper part of the cylinder at F, or into the lower 

 part at 1), as in Fig. 12, showing the piston in the state of ascending, and 

 Fig. 11, as descending. From the lower part of the cylinder in Fig. 11, the 

 steam escapes through D into the condenser B, (see Fig. 10) where it is 

 condensed by a jet of cold water, whicli plays into it constantly \ and the 

 uncondensed gases and water pass through the valve G during the ascending 

 stroke, and expelled at the valve Q into the hot well. When the steam pis- 

 ton P, Fig. 12, ascends, the steam from the upper part of the cylinder passes 

 through F down the pipe E to the condenser. The steam passages D and F 

 arc opened and closed by a D-slide, so called from its plan resembling the letter 

 D ; it is moved by the rod O, by tappets or other methods. 



• These are Watt's terms in giving an account of his articiibited parellelogram : 

 ** I have myself boen surprised by the reyularity of its action ; when I saw it move, 

 for the first tune, I was as much pleased with the novelty, as if it had buen tlie im^entiim 

 of another person'" 



Snieatun, wlio was a fjifat afiniirer of Watt's invention, did not believe that in prac. 

 tice, it coiihl become an economical and general UK'de of communicatini; directly rota- 

 tory nioveraent to an axle. He maintained tliat steam-enLjines conkl always be em- 

 ployed in raising water, wliich, when raist-d to a convenient lieigth, could bt uscfl in its 

 tall, to give motion to the buckets or floats of ordinary water wheels. In this respect, 

 however. Smeaton's ideas have not been carried out, aUhnugh I saw, in 1834, wliile on a 

 visit to Mr. Boulton's works, at Soho, an old steam-eriijine, which is stiU used to raise 

 water from a I:irii:c pond, and to pour it into the buckets of a large water wheel, ^\hen 

 the season is so dry as not to supply snfhcient w;iter from the stream generally used. — 

 IVoteof M. Arago. Leiipold sii>;gested llie idea of giving rotatoiy motion by means of 

 first raising the water into an elevated cistern, and then allowing it to fall on an over- 

 shot wheel, a drawing and desciipilun is given at page '1U3, vol. iii. Theatrum Afacki- 

 narum, — Note of Translator, 



2 L 2 



