ACT OF PARLIAMENT. 271 active; and it was now that the services of some of his philosophical friends were called into exertion. Among them, Doctor Roebuck was conspicuous. The petition was heard, and an act was passed, by which he had the sole privilege to manufacture and use his improved engines for twenty-five years after the date of his application; and, to crown his good fortune, Bolton became his partner in the manufacture of the engines, as well as in the share of the monopoly. His prospects were now not only bright but steady. The discussion of his claim in parliament had drawn public attention, both to the mechanic and his production. And from the length of the term, the most ample outlay had every prospect of being repaid. But above all, his becoming a manufacturer of his apparatus was fortunate for his reputation. His first ideas were capable of great improvement. The chances of producing new and more perfect applications and combinations were all in his favour; every engine was an experiment which might lead to an improvement in the next production; and by this means the possibility of his claim to invention being appropriated by others, for mere technical perfection, was prevented. The sale of the machine, as an article of trade, was conducted by Bolton, who showed himself in every way a master of commercial tactics. "And had Watt," says Playfair, "searched all Europe, he could not have found another man so calculated to introduce the invention to the public in a manner worthy of its importance." The public was invited to an inspection of the engine; the principles of its action were explained; its parts were described, and an estimate, both 272 ESTIMATE OF POWER. mechanical and economical, was made of its powers. But as, on this last head, something besides a manufacturer's assurance, was required to satisfy many who were to use and pay for the machines, a number of practical and scientific mechanics, whose personal and professional character placed their testimony beyond all suspicion, were invited to Soho, to witness a series of careful and rigid experiments made with the new engine; on the coals it consumed, on the work it performed, and on the time in which it did it. The results of these trials were compared with those of another series of experiments, made with equal care, in the presence of the same individuals, on Newcomen's engine, of the best construction, and in the best order. The superiority of the new engine, in every point, was thus shown to be immense. "And now," said the patentees," all that we ask from those who choose to have our engine, is the value of one-third part of the coals which are saved by using our improved machine instead of the old. With our engine, it will not, in fact, cost you but a trifle more than half the money you now pay to do the same work, even with our third-part included; besides an immense saving of room, water, and expense of repairs. The machine itself which we supply, is rated at that price which would be charged by any neutral manufacturer of a similar article. And, to save all misunderstanding, to engines of certain sizes, certain prices are affixed." To induce those who were either unable or unwilling to throw aside the expensive apparatus which they might have already in operation, Bolton and Watt took the old engines at a price in many instances much beyond their value, in part payment for the new; and they even erected engines worth some thousands of pounds, on condition of being paid for them when they produced the estimated advantage. In other cases, the parts of the old engines were appropriated; and where this was practised, the alteration marked, in a striking and novel manner, the extraordinary value of the improvement. The new clinder was placed within the old working cylinder which served as a jacket, to prevent the radiation of heat; the inner, which now became the working cylinder, was seldom more than half the size of the outer one; but yet the power of the mechanism was greater. To those, such as brewers, who still used horses, or those who calculated the effect of Newcomen's engine by that standard, a set of experiments were made, on the force which a horse exerts in moving certain descriptions of machinery; from a comparison of this, they said, by burning a certain quantity of coals, you will produce steam, which, used in our new engine, will do the same work as a horse. "Thus," Bolton said, "I will guarantee, with eighty-four pounds weight of Newcastle coal, to raise thirty millions of pounds weight one foot high; or the same quantity will grind eleven bushels of wheat; or it will slit and draw five hundred and sixty pounds weight of iron into nails. Therefore, by burning this quantity of coals, you will produce a power equal to that exerted by ten horses;" but in estimating this as equal to that number, his honourable mercantile spirit shone in a new and brighter light. It was of infinite importance, that the power of the new mechanism should appear favourable, in a comparison with that of animals. And with this view, the lower the estimate of a horse-power, 274 INVENTION OF THE COUNTER. the greater appeared the power of their engine, Smeaton, an engineer of unimpeached accuracy of statement and of great experience, had valued the force of a strong English horse as being equal to lifting a weight of 22,000 pounds one foot high in a day. But Watt and Bolton were not satisfied with this; they said that a horse could raise 83,000 pounds one foot high: thus stating the case against themselves almost to a third more : but they went still further; "one of our engines," they said, "are calculated so, that they will raise 44,000 pounds one foot high with a bushel of coals; and when we say our engines have the force of five, ten, or more horses, we mean, and guarantee, that they will lift 44,000 pounds for each horse power;" so that a machine which, according to Smeaton's estimate, would have a power of ten horses, Bolton and Watt only valued as exerting the power of five. A mode of proceeding so fair and liberal was admirably calculated to set at rest all suspicion, and the public began, at length, to look with more complacency on the invention. But when Bolton had induced many to use the condensing engine, he wanted means to fascertain the work which the engines performed; disputes might arise from valuing the savings of fuel, where the data were to be furnished by those who were most interested in making them of small value; and an inspector over every engine, to have kept an account of the quantity of coals used and work done, would have been as expensive as it would have been an invidious and inconvenient method. Watt's invention was put in requisition to enable his colleague to keep his accounts with clearness and accuracy; so that, while the inter-. ests of the patentees were ascertained, it should be. INVENTION OF THE COUNTER. 275 done in such a manner as not to leave even a shadow of suspicion, or an opening to litigation. And the result was, Watts contriving a means of keeping an account of the work of the engine, for days or months, or years, without the trouble of reckoning, in so perfect and simple a mode, that at every period, after an hour's work or a month's work, the quantity of steam which had been used should be ascertained by a mere inspection. This apparatus, which was called the counter, was formed of a series of small wheels, shut up in a box, having a dial and index-hand, to show how many revolutions had been made by the wheels. This apparatus was so placed, that every time the balanced lever rose, or descended, the wheels moved one tooth. It was sometimes attached to what was called the spring-beam floor, at other times it was attached to the lever beam. The box, which contained this mechanism, was shut by two locks, the key of one was kept by the proprietor of the engine, and the other key remained in the possession of Bolton and Watt. At certain periods, (every three months,) a confidential person in their employment visited the engines, and, in the presence of the proprietor, opened the box, and noted how many revolutions the wheel had made; from this it was easy to ascertain the quantity of coals that had been used; for, as this mechanism showed the number of times the piston had risen and fallen in the cylinder, that gave the number of times the cylinder had been filled with steam; and as it had been ascertained how much steam could be made from a bushel of coals, that gave the quantity of fuel that had been used in the Watt engine; and as the difference between the use of the new and old machine had been ascertained from the experiments, the third part |