Section II.—The Contemporaries of James Watt

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Section II.—The Contemporaries of James Watt.

In the chronology of the steam-engine, the contemporaries of Watt have been so completely overshadowed by the greater and more successful inventor, as to have been almost forgotten by the biographer and by the student of history. Yet, among the engineers and engine-builders, as well as among the inventors of his day, Watt found many enterprising rivals and keen competitors. Some of these men, had they not been so completely fettered by Watt’s patents, would have probably done work which would have entitled them to far higher honor than has been accorded them.

William Murdoch was one of the men to whom Watt, no less than the world, was greatly indebted. For many years he was the assistant, friend, and coadjutor of Watt; and it is to his ingenuity that we are to give credit for not only[133] many independent inventions, but also for the suggestions and improvements which were often indispensable to the formation and perfection of some of Watt’s own inventions.

Murdoch was employed by Boulton & Watt in 1776, and was made superintendent of construction in the engine department, and given general charge of the erection of engines. He was sent into Cornwall, and spent in that district much of the time during which he served the firm, erecting pumping-engines, the construction of which for so many years constituted a large part of the business of the Soho establishment. He was looked upon by both Boulton and Watt as a sincere friend, as well as a loyal adherent, and from 1810 to 1830 was given a partner’s share of the income of the firm, and a salary of £1,000. He retired from business at the last of the two dates named, and, dying in 1839, was buried near the two partners in Handsworth Church.

Fig. 36.—Murdoch’s Oscillating Engine, 1785.

Murdoch made a model, in 1784, of the locomotive patented by Watt in that year. He devised the arrangement of “sun-and-planet wheels,” adopted for a time in all of Watt’s “rotative” engines, and invented the oscillating steam-engine (Fig. 36) in 1785, using the “D-slide valves,” G, moved by the gear, E, which was driven by an eccentric on the shaft, without regard to the oscillation of the cylinder, A. He was the inventor of a rotary engine and of many minor machines for special purposes, and of many machine-tools used at Soho in building engines and machines. He seems, like Watt, to have had special fondness for the worm-gear, and introduced it wherever it could properly take the place of ordinary gearing. Some of the machines designed by Watt and Murdoch, who always worked well together, were found still in use and in good working condition by the author when visiting the works at Soho in 1873. The old mint in which, from 1797 to 1805, Boulton had coined 4,000 tons of copper, had then been pulled down, and a new mint had been erected in 1860.[134] Many old machines still remained about the establishment as souvenirs of the three great mechanics.

Outside of Soho, Murdoch also found ample employment for his inventive talent. In 1792, while at Redruth, his residence before finally returning to Soho, he was led to speculate upon the possibility of utilizing the illuminating qualities of coal-gas, and, convinced of its practicability, he laid the subject before the Royal Society in 1808, and was awarded the Rumford gold medal. He had, ten years earlier, lighted a part of the Soho works with coal-gas, and in 1803 Watt authorized him to extend his pipes throughout all the buildings. Several manufacturers promptly introduced the new light, and its use extended very rapidly.

Still another of Murdoch’s favorite schemes was the transmission of power by the use of compressed air. He drove the pattern-shop engine at Soho by means of air from the blowing-engine in the foundery, and erected a pneumatic lift to elevate castings from the foundery-floor to the canal-bank.[135] He made a steam-gun, introduced the heating of buildings by the circulation of hot water, and invented the method of transmitting packages through tubes by the impulse of compressed air, as now practised by the “pneumatic dispatch” companies. He died at the age of eighty-five years.

Fig. 37.—Hornblower’s Compound Engine, 1781.

Among the most active and formidable of Watt’s business rivals was Jonathan Hornblower, the patentee of the “compound” or double-cylinder engine. A sketch of this engine, as patented by Hornblower in 1781, is here given (Fig. 37). It was first described by the inventor in the “Encyclopædia Britannica.” It consists, as is seen by reference to the engraving, of two steam-cylinders, A and B—A being the low and B the high pressure cylinder—the steam leaving the latter being exhausted into the former, and, after doing its work there, passing into the condenser, as already described. The piston-rods, C and D, are both connected to the same part of the beam by chains, as in the other early engines. These rods pass through stuffing-boxes in the cylinder-heads, which are fitted up like those seen on the Watt engine. Steam is led to the engine through the pipe, G Y, and cocks, a, b, c, and d, are adjustable, as required, to lead steam into and from the cylinders, and are moved by the plug-rod, W, which actuates handles not shown. K is the exhaust-pipe leading to the condenser. V is the engine feed-pump rod, and X the great rod carrying the pump-buckets at the bottom of the shaft.

The cocks c and a being open and b and d shut, the steam passes from the boiler into the upper part of the steam-cylinder, B; and the communication between the lower part of B and the top of A is also open. Before starting, steam being shut off from the engine, the great weight of the pump-rod, X, causes that end of the beam to preponderate, the pistons standing, as shown, at the top of their respective steam-cylinders.

The engine being freed from all air by opening all the[136] valves and permitting the steam to drive it through the engine and out of the condenser through the “snifting-valve,” O, the valves b and d are closed, and the cock in the exhaust-pipe opened.

The steam beneath the piston of the large cylinder is immediately condensed, and the pressure on the upper side of that piston causes it to descend, carrying that end of the beam with it, and raising the opposite end with the pump-rods and their attachments. At the same time, the steam from the lower end of the small high-pressure cylinder being let into the upper end of the larger cylinder, the completion of the stroke finds a cylinder full of steam transferred from the one to the other with corresponding increase of volume and decrease of pressure. While expanding and diminishing in pressure as it passes from the smaller into the larger[137] cylinder, this charge of steam gradually resists less and less the pressure of the steam from the boiler on the upper side of the piston of the small cylinder, B, and the net result is the movement of the engine by pressures exerted on the upper sides of both pistons and against pressures of less intensity on the under sides of both. The pressures in the lower part of the small cylinder, in the upper part of the large cylinder, and in the communicating passage, are evidently all equal at any given time.

When the pistons have reached the bottoms of their respective cylinders, the valves at the top of the small cylinder, B, and at the bottom of the large cylinder, A, are closed, and the valves c and d are opened. Steam from the boiler now enters beneath the piston of the small cylinder; the steam in the larger cylinder is exhausted into the condenser, and the steam already in the small cylinder passes over into the large cylinder, following up the piston as it rises.

Thus, at each stroke a small cylinder full of steam is taken from the boiler, and the same weight, occupying the volume of the larger cylinder, is exhausted into the condenser from the latter cylinder.

Referring to the method of operation of this engine, Prof. Robison demonstrated that the effect produced was the same as in Watt’s single-cylinder engine—a fact which is comprehended in the law enunciated many years later by Rankine, that, “so far as the theoretical action of the steam on the piston is concerned, it is immaterial whether the expansion takes place in one cylinder, or in two or more cylinders.” It was found, in practice, that the Hornblower engine was no more economical than the Watt engine; and that erected at the Tin Croft Mine, Cornwall, in 1792, did even less work with the same fuel than the Watt engines.

Hornblower was prosecuted by Boulton & Watt for infringement. The suit was decided against him, and he[138] was imprisoned in default of payment of the royalty, and fine demanded. He died a disappointed and impoverished man. The plan thus unsuccessfully introduced by Hornblower was subsequently modified and adopted by others among the contemporaries of Watt; and, with higher steam and the use of the Watt condenser, the “compound” gradually became a standard type of steam-engine.

Arthur Woolf, in 1804, re-introduced the Hornblower or Falck engine, with its two steam-cylinders, using steam of higher tension. His first engine was built for a brewery in London, and a considerable number were subsequently made. Woolf expanded his steam from six to nine times, and the pumping-engines built from his plans were said to have raised about 40,000,000 pounds one foot high per bushel of coals, when the Watt engine was raising but little more than 30,000,000. In one case, a duty of 57,000,000 was claimed.

Fig. 38.—Bull’s Pumping-Engine, 1798.

Large scale image (434 kB).

The most successful of those competitors of Watt who endeavored to devise a peculiar form of pumping-engine, which should have the efficiency of that of Boulton & Watt, and the necessary advantage in first cost, were William Bull and Richard Trevithick.[42] The accompanying illustration shows the design, which was then known as the “Bull Cornish Engine.”

The steam-cylinder, a, is carried on wooden beams, b, extending across the engine-house directly over the pump-well. The piston-rod, c, is secured to the pump-rods, d d, the cylinder being inverted, and the pumps, e, in the shaft, f, are thus operated without the intervention of the beam invariably seen in Watt’s engines. A connecting-rod, g, attached to the pump-rod and to the end of a balance-beam, h, operates the latter, and is counterbalanced by a weight, i. The rod, j, serves both as a plug-rod and as an air-pump connecting-rod. A snifting-valve, k, opens[139] when the engine is blown through, and relieves the condenser and air-pump, l, of all air. The rod, m, operates a solid air-pump piston, the valves of the pump being placed on either side at the base, instead of in the pump-bucket, as[140] in Watt’s engines. The condensing-water cistern was a wooden tank, n. A jet “pipe-condenser,” o, was used instead of a jet condenser of the form adopted by other makers, and was supplied with water through the cock, p. The plug-rod, q, as it rises and falls with the pump-rods and balance-beam, operates the “gear-handles,” r r, and opens and closes the valves, s s, at the required points in the stroke. The attendant works these valves by hand, in starting, from the floor, t. The operation of the engine is similar to that of a Watt engine. It is still in use, with a few modifications and improvements, and is a very economical and durable machine. It has not been as generally adopted, however, as it would probably have been had not the legal proscription of Watt’s patents so seriously interfered with its introduction. Its simplicity and lightness are decided advantages, and its designers are entitled to great credit for their boldness and ingenuity, as displayed in their application of the minor devices which distinguish the engine. The design is probably to be credited to Bull originally; but Trevithick built some of these engines, and is supposed to have greatly improved them while working with Edward Bull, the son of the inventor, William Bull. One of these engines was erected by them at the Herland Mine, Cornwall, in 1798, which had a steam-cylinder 60 inches in diameter, and was built on the plan just described.

Another of the contemporaries of James Watt was a clergyman, Edward Cartwright, the distinguished inventor of the power-loom, and of the first machine ever used in combing wool, who revived Watt’s plan of surface-condensation in a somewhat modified form. Watt had made a “pipe-condenser,” similar in plan to those now often used, but had simply immersed it in a tank of water, instead of in a constantly-flowing stream. Cartwright proposed to use two concentric cylinders or spheres, between which the steam entered when exhausted from the cylinder of the engine,[141] and was condensed by contact with the metal surfaces. Cold water within the smaller and surrounding the exterior vessel kept the metal cold, and absorbed the heat discharged by the condensing vapor.

Fig. 39.—Cartwright’s Engine, 1798.

Cartwright’s engine is best described in the Philosophical Magazine of June, 1798, from which the accompanying sketch is copied.

The object of the inventor is stated to have been to remedy the defects of the Watt engine—imperfect vacuum, friction, and complication.

In the figure, the steam-cylinder takes steam through the pipe, B. The piston, R, has a rod extending downward to the smaller pump-piston, G, and upward to the cross-head, which, in turn, drives the cranks above, by means of connecting-rods. The shafts thus turned are connected[142] by a pair of gears, M L, of which one drives a pinion on the shaft of the fly-wheel. D is the exhaust-pipe leading to the condenser, F; and the pump, G, removes the air and water of condensation, forcing it into the hot-well, H, whence it is returned to the boiler through the pipe, I. A float in H adjusts an air-valve, so as to keep a supply of air in the chamber, to serve as a cushion and to make an air-chamber of the reservoir, and permits the excess to escape. The large tank contains the water supplied for condensing the steam.

The piston, R, is made of metal, and is packed with two sets of cut metal rings, forced out against the sides of the cylinder by steel springs, the rings being cut at three points in the circumference, and kept in place by the springs. The arrangement of the two cranks, with their shafts and gears, is intended to supersede Watt’s plan for securing a perfectly rectilinear movement of the head of the piston-rod, without friction.

In the accounts given of this engine, great stress is laid upon the supposed important advantage here offered, by the introduction of the surface-condenser, of permitting the employment of a working-fluid other than steam—as, for example, alcohol, which is too valuable to be lost. It was proposed to use the engine in connection with a still, and thus to effect great economy by making the fuel do double duty. The only part of the plan which proved both novel and valuable was the metallic packing and piston, which has not yet been superseded. The engine itself never came into use.

At this point, the history of the steam-engine becomes the story of its applications in several different directions, the most important of which are the raising of water—which had hitherto been its only application—the locomotive-engine, the driving of mill-machinery, and steam-navigation.

Here we take leave of James Watt and of his contemporaries,[143] of the former of whom a French author[43] says: “The part which he played in the mechanical applications of the power of steam can only be compared to that of Newton in astronomy and of Shakespeare in poetry.” Since the time of Watt, improvements have been made principally in matters of mere detail, and in the extension of the range of application of the steam-engine.

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