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“ was the best.' I recommended the Admiralty College to “ erect a steam-engine; this occasioned a good deal of con“ versation between me and the gentlemen of science in that

country, particularly a Mr. Model, the Court apothecary, a

gentleman of great reputation, and one of the first chemists “ of the age, whom I had instructed in the doctrine of latent “ heat. I wrote to Mr. Watt, desiring him to undertake the “ erection of an engine. Mr. Watt, with that liberality which “ is natural to him, declined interfering in it. The expres“sion of his letter was, 'I think you are fully able to conduct " that project, and it will do you credit in the country where "you are.' The day that I received this letter, I went to “ drink tea with Mr. Model; and found sitting with him Mr.

Æpinus, a gentleman no less eminent for his beautiful “ theory of magnetism and electricity. I mentioned Mr. “ Watt's genteel declinature, and also a passage of his letter, “ in which he said that by admitting steam to press down the “ piston, its want of perfect tightness was not so hurtful as

appeared at first sight, because the steam which got past “ would only be lost, but would not choke the engine. Model “ broke out into an exclamation, confirming what I said. “ Æpinus did not see the force of what we said, and Model " took out his pencil to make a sketch which would explain “ it to him. Not readily finding a bit of paper, I pulled a bit "out of my pocket, on which he made a sketch. This hap"pened to be an official report, which I had that day received " at Cronstadt, and which I kept with many things of this “ kind, and they came home with my other papers.

I submit it to the inspection of the Court, and presume it “ will be acknowledged as a convincing proof that Mr. Model

completely understood Boulton and Watt's method; and " that much less information than is given in the specifi“cation is sufficient for enabling an intelligent engineer to erect an effective engine, or to comprehend Mr. Watt's principles.”

2. It was objected, secondly, in particular, that the mode of condensation, (by injection of a jet of cold water), was not specified.

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But as this mode was familiarly known to all engineers, and even to most common mechanics, to have been ordinarily practised in Newcomen's engines, the repetition of it by Mr. Watt in his specification was quite uncalled for; no departure from the former practice, in that particular, being intended by him to be adopted.

3. That the relative proportions which the condenser should bear to the cylinder, and which the air-pump should bear to the condenser, were not specified, so as to render it unnecessary to resort to experimental trials, in the construction of engines on the new principles.

On this head, it was readily shown that it was not requisite, according to any fair interpretation of the law, that the specification should describe the proportions of the various parts of an engine so that any person whatsoever might, without previous instruction as an engineer, be thereby enabled at once to construct a perfect steam-engine; that it was quite sufficient if it gave the information needful for such as had both received some previous education, and had some just right to be regarded as engineers; that the exact proportions of either the condenser or the air-pump were quite immaterial to the satisfactory performance of the engine, provided only they were large enough to do the usual work of condensation and pumping; and that the magnitude proper for each of them could not fail to be known to all who possessed the amount of previous knowledge required for such business before the new invention was made. “It is not material,” said Lord Kenyon, “whether the condenser shall be circular, square,

octagon, decagon, or what shape it shall be.” “They quarrel “ with us,” said Mr. Rous, in his very able speech in the Court of King's Bench, in 1799, “ for not giving a form of a u condenser. Neither form, nor size, nor position of the con“ denser is material. To have specified these would have “ been to deceive. When the valve is opened, the steam, “ from its elastic nature, escapes, and is condensed. If there “ be any choice as to form, size, or position, these must

depend on the local means of keeping the condenser cold; “ and when the artist is told that it must be kept cold, he

has every information on these heads which an artist can “ require. Nothing more is now to be done but to get rid of “ the air and elastic vapour, which cannot be removed by the “ means before employed. This Mr. Watt directs us to “ extract by a pump, worked by the engine, or otherwise, at " the pleasure of the artist. To complete the invention of “ “Mr. Watt, it was only necessary that this vapour should not “ be suffered to accumulate. The common mode of doing “ this, is to suspend the pump to the working beam of the

engine. I presume it will not be disputed that the con“ denser and the pumps are tangible and vendible substances. “ As to the perfection of this part of the invention, I cannot “ demonstrate it to be equal to the perfection of the other

part, by the bare inspection of the specification. I must “ refer my adversary to the testimony of witnesses, and the “ evidence of the gauge annexed to the engine. From these “ he will learn, that the exhaustion is nearly equal to that of “ the air-pump, and, consequently, that all sensible resistance “ to the action of the piston is removed."*

4. That of the various substances specified to be employed instead of water, to render the piston or other parts of the engines air and steam-tight, viz. “oils, wax, resinous bodies, “ fat of animals, quicksilver, and other metals in their fluid “ state," only one, (the fat of animals), was useful and economical in practice; and quicksilver, in particular, by cortosion and amalgamation, would injure any parts of the engine that might happen to be made of brass, to which it might get access.

There was evidently nothing in this objection deserving notice; as it was pretty certain that if any one of the substances specified was both cheapest and best, (as was said to be the case with mutton suet), that would soon be adopted, to the exclusion of the rest. As for the argument from the quicksilver, all mechanics at all acquainted with their business knew very well that that metal ought not to be applied to any brass work; and the Chief Justice could not help obsery

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* Appendix to .Mechanical Inventions of Watt,' No. VI. p. 232.

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ing, that so mercurial an objection was scarcely to be considered as a subject for grave discussion.

. 5. That no annexed drawing or model of the new engine was lodged with the specification.

Unfortunately, the numerous piracies that were successfully practised, showed but too forcibly, that no drawing or model was requisite to enable counterfeits of the new engine to be made. The fact was, that either drawing or model was not only quite unnecessary, and, from the endless variety of forms in which the invention might be applied, quite useless; but it might really have injured the efficacy of the patent by limiting the extent of its application. For it must always be remembered, that the invention was not, as the infringers tried to represent it), of a new engine, but of a new method of saving fuel, by condensing the steam in a vessel apart from the cylinder. That separate condensation was the thing patented, in whatsoever form, or to whatsoever engine it might be applied; although the best mode of carrying out the principle, by valves, alternate communication, &c., was clearly pointed out, so as to be intelligible to all engineers or mechanics of ordinary capacity and education in their trade. “ We called," said Mr. Rous, "all the most eminent theorists, “ and practical engineers of all descriptions, who swore that “ to construct the engine from this description was so per

fectly easy, that no man of tolerable skill in his profession “ could mistake." The allegation of the defendants on this head was also triumphantly refuted by the remarkable circumstance given in evidence by Professor Robison, which has been already cited;* as well as by the fact, that “another

engineer, who superintended twelve of Newcomen's engines “ in Yorkshire, under a misapprehension respecting the time " at which the patent would expire, had actually formed and “ prepared all the parts, which have since been used with com“plete success." +

“ "I know," adds Professor Robison, “ that it has been

* See pp. 394, 395, suprà.
† Appendix to ‘Mechanical Inventions of Watt,' No. VI. p. 229.

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“repeatedly objected to this opinion of men of science con

cerning the sufficiency of the specification, that Mr. Watt's own accounts are in opposition to it. He had to encounter many difficulties before he perfected his machine, even after obtaining his patent. I know this well. But this was " chiefly in subordinate parts of the undertaking. I firmly “ believe that the great principles were as perfect in his mind “ in a few hours, as they are at this day; and that the phy“sical parts of the problem were as completely solved by his “ first model, as they are now by his best engines. But when " Mr. Watt was engaged in bringing the contrivance to per“ fection, he wished to perfect every part. He who wished "to make his engine not only the best, but the cheapest in " the world,ếhe struggled long, in opposition to his own “judgment, at Dr. Roebuck's instance, to perform the con“ densation without injection. He had a predilection for the “ wheel engine, and much time and labour were spent on it, “ while he was uncertain whether he should bring this, or the

reciprocating engine, first to the market. He had expe“ rience to acquire in great works, and in the practice of "several trades employed in such constructions. He had “ workmen to instruct, and to form; and to keep with him, " after they had acquired from him a little knowledge, and

were worth bribing away from him. But the chief cause of " the delay was that indelible trait in Mr. Watt's character,

that every new thing that came into his hands became a

subject of serious and systematic study, and terminated in “ some branch of science. How rarely do we meet with such

a conjunction of science and art -how precious when it is “ found ;-how much then does it deserve to be cherished ! “What advantages have been derived within these twenty

years from this fortunate union ;-how much then does it “ become our Courts to encourage and support it against the “ unprincipled attacks of ignorant and greedy plagiarists, "who would deceive our men of property, ruin them by

expensive projects which terminate in disappointment, and "thus discourage those who alone can by their capital give

any effectual aid to the energy and genius of this country!

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