But never doubt our right.”
Watt’s first surmise, that the Hornblowers intended to work their engine by heated air or gas, had set Boulton upon a series of inquiries and experiments on the subject, in which he was assisted by Dr. Priestley, who had shortly before settled in Birmingham, and was a willing co-operator in all investigations of this nature. Their object was to ascertain whether it was practicable to produce mechanical power by the absorption and condensation of gas on the one hand, and by its disengagement and expansion on the other.
“What you propose,” Watt wrote, “is exceeding probable, and akin to what I have long contemplated—the use of mixed air and steam, which have a wonderful expansion and contraction. Nevertheless, I fear that there is in all such cases a proportional assumption of latent heat; but be it tried though it be beginning a new series of vexations and expense.... I suspect that a forcible compression would hinder the gas from separating from the water, and on the contrary any tolerable degree of vacuum would hinder the water from attracting it; but perhaps part of both may be used.... My greatest hope is in the expansive engine with double or single cylinder, which I consider as proved by many facts, and shall send you my ideas of the execution of it very soon. At the same time I am clear to take the air patent, which, as I have worded the petition, may include some other improvements on the steam-engine.... I hope my last letters have relieved you, as the knowledge of the Horners’ being a steam-engine working on our principle relieved me. I have some trust in the judges, though I have little in the law; and I think impartial people will regard us as injured persons, and not suffer the thief of our horse to escape because he has painted him of another colour.”[221]
Watt’s fears for his patent were about this time excited anew by the great Arkwright trial, in which Arkwright was nonsuited, and compelled to forego the rights derived from his improvements and combinations of spinning-machinery. The principal ground on which the patent was set aside was that the specification was unintelligible. On this, Watt observed,—
“Though I do not love Arkwright, I don’t like the precedent of setting aside patents through default of specification. I fear for our own. The specification is not perfect according to the rules lately laid down by the judges. Nevertheless, it cannot be said that we have hid our candle under a bushel. We have taught all men to erect our engines, and are likely to suffer for our pains.... I begin to have little faith in patents; for, according to the enterprising genius of the present age, no man can have a profitable patent but it will be pecked at, and no man can write a specification of a fire-engine that cannot be evaded, if the words and not the true intent and meaning be attended to. As kissing goes by favour, and as, in dubious cases, men are actuated by their prejudices, so, where a blue is very like a green they may decide either way.”[222]
Watt continued to be alarmed by the rumours of the forthcoming Hornblowers’ engine. “I have heard,” he wrote, “that a female confidant of Jonathan’s has seen the engine, and says that they evaporate half a hogshead of water with one ounce of coals! ... that in a few days they are to publish in print what their invention is, illustrated with a copper-plate. Then we shall see and admire, if God pleaseth; I hope we shall not believe and tremble.” Later he wrote,—“Our cause is good, and yet it has a bad aspect. We are called monopolists, and exactors of money from the people for nothing. Would to God the money and price of the time the engine has cost us were in our pockets again, and the devil might then have the draining of their mines in place of me. Yet all are not alike. Some are just, and I believe do not grudge us, and some are friendly. All this is to no purpose. The law must decide whether we have property in this affair or not, and we must submit to what we cannot help.”[223]
At length Watt learnt the precise nature of the Hornblowers’ invention. “It is no less,” he wrote Boulton, “than our double-cylinder engine, worked upon our principle of expansion.” This was an old idea of Watt’s, which he had pursued while labouring upon his model at Kinneil. “It is fourteen years,” he said, “since I thought of the double-cylinder engine, and I think that I mentioned it to Mr. Smeaton, when I explained the expansion engine to him in your parlour, some years ago. Wm. Murdock and Mr. Henderson can testify to my having mentioned it to them; but this of the Horners seems to be a different thing, being hung on the same beam.”[224] As early as May, 1769, he had communicated to Dr. Small a clear and explicit description of his method of working steam expansively; and he adopted the principle in the Soho engine, in 1778, as well as in the Shadwell engine erected in the same year. He was, however, prevented carrying it out extensively in practice by the inexpertness of the workmen. “Though the effect of the steam,” he explained to a correspondent, “is thereby increased 50 per cent. (by theory 100 per cent.), it cannot be done without rendering the machine more complicated than we wish; and simplicity is a most essential point in mechanics. There are other contrivances known to us which would increase the effect in an inferior degree, say from one-fourth to one-sixth, but they are all attended with peculiar inconveniences which forbid their use until the illiterate and obstinate people who are intrusted with the care of the engines become more intelligent and better acquainted with the machine.”[225]
Though suffering much from his usual headaches, which frequently disabled him from thinking, Watt finished the drawings of the rotary engine in a week, and forwarded them to Boulton at Soho. “I believe,” he said in a later letter, “a well-regulated expansive-engine is the ne plus ultra of our art.” But he intimated that a new trouble had come upon him in the shape of another inventor of a steam-engine in which all the distinctive principles of his own invention were embodied. “If he be engine mad,” said Watt, “and if it be agreeable to you, he shall have my share of them, provided he will come to my price. I wish to retire, and eat my cake in peace, but will not go without the cake. All mankind seem to have resolved to rob us. Right or wrong, they will pluck the meal from our mouths.”[226] Boulton, on his next journey to London, called upon the alleged inventor, a Mr. Ewer, and declared to Watt that the invention, so far as it was new, was not worth a farthing, and that all that was good in it was borrowed from their engine. “Though the white marks on your cow or your horse,” said he, “may be changed to black, the cow and horse are not the less your property.” He therefore counselled Watt to relieve himself of all anxiety on this account. Watt replied, “Ewer seems to have a genius more capable of inventing than of prudently examining the merits of his invention. Poets lose half the praise they would otherwise get did they but tell us what they discreetly blot. We must publish a book of blots.”
OLD ENGINE-HOUSE AT DALCOATH.