.r' Copyright, 1891, By DopD, Mead, and Co. %4« rights reserved. John Wilson and Son, Cambridge. CONTENTS. CHAPTER PAGE I. Old Legends. — Steam in Earlier Times. — James Watt i II. Early Experiments in Steam-Naviga- tion .... 28 III. Robert Fulton's Early Life .... 48 IV. The Artist as Engineer 60 V. The Engineer, as Inventor, in Sub- marine Warfare . 69 VI. Fulton's Experiments with Steam. — The "Clermont" loi VII. River and Ocean Steam-Fleets ... 146 VIII. Ocean Steamers. — The Outlook . . 167 ROBERT FULTON. I. OLD LEGENDS. STEAM IN EARLIER TIMES. JAMES WATT. Robert Fulton has often, if not generally, been assumed to have been the inventor of the steamboat, as Watt is generally supposed to be the inventor of the steam-engine, which constitutes its motive ap- paratus. But this notion is quite incorrect. The invention of the steam-engine and that of the steam- boat alike are the results of the inventive genius, not of any one man or of any dozen men, but have been the outcome of the inventive powers of the human race, exerted at intervals throughout the whole period of recorded history. An invention is usually, or is at least assumed to be, the product of the genius of some great mechanic, acting, as did the genii of old, by a single effort of the mysterious power. In this sense of the word, the steam-engine was never in- vented ; rather it is the culmination of a long series of inventions of detail, and of improvements upon the earliest crude conceptions, and is the product of growth in a definite direction, and toward a now well- defined end. / But while Fulton was not the inventor of the steamboat, and while James Watt was not the 2 ROBERT FULTON. inventor of the steam-engine, in a proper sense, it is the unquestionable fact that the latter was the first to secure a general introduction of the machine into practical use ; and the former was the first to make the steamboat a commercial success, and to make its ultimate and permanent employment for marine transportation sure. As an inventor, Fulton accom- plished far less than Watt ; in fact, he did compara- tively little in this realm of intellect. Watt invented many improvements of the steam-engine, and left it in vastly better form than when he found it, as it came from the hands of his predecessors, Newcomen and Galley. He gave the already well-shaped machine the separate condenser, the steam-jacket, the double- acting form, the rotative type, the expansive system, the governor, and the " engineer's stethoscope," — the indicator. Fulton did nothing to modify the engine, or to improve the steamboat even. He simply took the products of the genius of other mechanics, and set them at work, in combination, and then ap- plied the already known steamboat, in his more satis- factorily proportioned form, to a variety of useful purposes, and with final success. /it is this which constitutes Fulton's claim upon the gratitude and the remembrance of the nations. And it is quite enough. The knowledge of the expansive power of steam was of earlier date than the Christian era ; forms of steam-engine antedated Watt by two thousand years ; the modern type of steam-engine was the invention of Newcomen rather than of Watt, and preceded that famous improver by nearly a century ; the steamboat OLD LEGENDS. 3 was said to have been constructed by several inven- tors long before the world witnessed the birth of Fulton ; other inventors had built and successfully operated steamboats with paddles, other boats with wheels, steam-vessels with screws, long before Fulton entered upon his great and glorious career. The simple fact is, therefore, as already indicated, that, like all really great and important inventions, these were the final fruition of minute germs of invention in earlier centuries, growing and gaining, century by century, throughout long periods of time. The fa- mous inventor is usually he who in the end brings into full bearing the hitherto unknown and unnoticed invention, — he who at last makes it useful to man- kind. This last was the mission of Fulton ; and it is this which has entitled him to all the credit as an engineer, and all the fame, which has been indisputably his. Before taking up our study of the life of Fulton, and of its magnificent results, as already exhibited after less than a century has passed, it will be both interesting and profitable to review the past, and learn, as well as history permits, the details of that growth which has led us finally to such wonderful fruition. In doing so, we will follow the thread of the narrative as it has already been given by the author in a more formal treatise.^ A rapid summary of the facts, and a study of their relations to our subject, beginning with earliest his- tory, and following this development up to the time of Fulton, will enable us to more intelhgently and 1 History of the Growth of the Steam-Engine, by R. H Thurston. New York. D. Appleton & Co. 1878. 4 ROBERT FULTON. satisfactorily weigh our debt to that great man, and measure the obUgation of the world, and especially of his own country. The knowledge of the latent power of steam prob- ably antedates history ; rude forms of apparatus for utilizing that force are described in the earliest of ancient works ; yet the invention of a steam-engine, in the proper sense of that term, only took place within two centuries, and the steam-engine of the present time has been the outcome of a succession of inventions and improvements which are only now culminating in the production of an engine which' science indicates to be that which must be regarded as the final form of that remarkable motor. The principles of its construction, and especially those of its operation, are now well understood, and all its faults and wastes of either heat-energy or mechanical power are known and measured, their causes ascer- tained, and, in a general way, their methods of rem- edy determined. We are now gradually overcoming the practical obstacles to the reduction of the machine to the best possible proportions, and its plan to the ideal form. The history of the steam-engine is ex- ceedingly interesting, and to the philosopher especially so, as illustrating the fact that " great inventions are rarely the work of any one mind," but are " either an aggregation of minor inventions or the final step of a progression ; " " not a creation, but a growth, — as truly so as that of the trees in the forest." ^ 1 History of the Growth of the Steam-Engine, by R. H. Thurston. New York. D, Appleton & Co. (International Series.) OLD LEGENDS. The first account of what has been termed the germ of the steam-engine appears in the works of Hero the Younger, who hved, as is supposed, in the second century before Christ, at Alexandria, in Egypt. In his " Pneumatica " he describes a multitude of devices, s o m e o f them very ingenious, but mainly mere toys, in which the heat- energy of fire, or of the sun, is applied for transformation into mechanical power through the interme- diary of steam. He shows several forms of fountain, now known as the Hero fountain ; contrivan- ces for opening tem- ple doors by steam ; musical instruments^ — at least, so called, — and other such un- important trifles. Amongst this collection of curious illustrations of the non-utilitarian character of the Greek civilization, is found a real steam-engine, such as is illustrated by the accompanying engraving.^ The picture here given is a modern and highly 1 Thurston's Manual of the Steam-Boiler, p. 2. New York. J. Wiley & Sons. 1890. Fig. I. — Hero's Steam-Engine. 6 ROBERT FULTON. ornamented reproduction of Hero's machine, which is earliest shown in Stuart's " History of the Steam- Engine," 1829, and reproduced by the author in later publications. Curiously enough, this little ma- chine, which has often been reproduced, unwittingly, by modern inventors, and actually used with a fair degree of satisfaction, illustrates a form of engine which is " theoretically," ideally perfect. Its opera- tion under the theoretically best conditions, assum- ing it made with similar perfection and to be free from friction-wastes, would give highest possible effi- ciency and economy in the use of steam. But this would involve its operation at inapproachable veloci- ties and the impracticable condition of being friction- less; nevertheless, it is perfectly possible to secure such favourable conditions in practice as will make a fairly economical machine, when placed in comparison with the forms of engine which modern invention has produced. Its action is simple and easily seen. Steam is made in the boiler which forms its base, and passes up through one or both of the hollow support- ing columns or pipes, entering the axis of the whirl- ing globe, filling it at a pressure determined by the rate at which steam is formed ; and it is then ex- panded, finally issuing from the projecting arms or ajutages, and by its reaction turning the globe with considerable force and at high speed. Modern en- gines of this construction have been used quite suc- cessfully in driving factories and mills, and have been found to use no very extravagant amount of steam ; but have finally been thrown out, on account, mainly, STEAM IN EARLIER TIMES. 7 of their cost for repairs ; the whirHng arms being usu- ally rapidly cut away by their swift passage through the steam-laden atmosphere in which they necessarily work. Ideally, the machine is an " expansion- engine " of the most perfect type. From the days of Hero, however, nothing more is heard of the use of steam in any apparatus, nor is any machine produced capable of doing work in that manner. All through the early and the middle ages the force of confined steam and other vapours is evi- dently known, but no attempt that may be regarded as at all serious was made to utilize its latent power. Little "seolipiles" — -vessels in which steam was pro- duced and from which it issued in a jet which was sometimes employed to cause an induced current of air with which to blow the fire — were the only steam- engines, until, about the sixteenth century, it seems to have been suspected by one or another of the wool- gathering philosophers and the plodding mechanics of those days that steam had a somewhat higher mis- sion. At about the end of that century and the beginning of the seventeenth, we find records of various contrivances, in the application of steam to useful purposes, which indicate that at last the minds of men were awakening to the consideration of the problem of the centuries. These inventions, if it can be said, fairly, that they were inventions, were commonly directed to the application of the force of confined steam to the raising of water through considerable heights, as in the draining of mines, or in furnishing a house-supply. Da Porta, 8 ROBERT FULTON. in 1 60 1, De Caus in 1605 to 16 15, and Branca, 1629, were among those who began to suggest, rather than to practise, the apphcation of steam to useful work. The first two pictured contrivances for raising water, which were, however, but distant imitations of the notions of Hero ; while the last-named gave drawings, with some elaboration, of machines, by the action of steam-jets, usually impinging against vanes, driving mills and metallurgical machinery. At about the latter time, the second Marquis of Worcester began his now famous career of invention, and probably as early as 1630 had devised what is known as his "engine" or his " fire-engine ;" a machine, however, which was really but the Hero fountain on an enlarged and somewhat more practi- cally available scale, and in better form. He did apply it to its purpose of raising water, though ; and this constitutes for him a legitimate and sufficient claim for remembrance and honour. He was the first to use steam — so far as is positively known — for industrial ends. It is known that he was engaged in erecting an engine at least as early as 1648, but his patents were only issued in 1663. It seems very certain that the marquis built two or more of these " fire-engines ; " but their exact form is unknown, and it is only certain that he profited nothing by his ingenuity and enterprise. He finally died unsuccess- ful and in comparative poverty. His widow was as unhappy and unfortunate as her husband, and died in 1 68 1 without having gained a foothold for her spouse's invention. STEAM IN EARLIER TIMES. 9 The death of this truly great man, inventor and statesman as he was, in the highest sense, did not, however, put an end to the progress which he had initiated. His friend and successor in this work, Sir Samuel Morland, made himself thoroughly familiar with the subject, secured opportunities to construct a number of such engines, and became so well in- formed as to their capabilities that he published an account of the apparatus, in which paper he intro- duced tables of the number and sizes of the working cylinders required to raise given quantities of water to specified heights in stated times ; thus, for the first time, constructing the now usual specifications for use in de- termining the requirements of purchasers. Yet neither the machines of Worcester nor those of Morland be- came generally used. These men were in advance of their time ; and it was only when, some years later. Captain Savery, — a man of talent both as an engineer and a man of business, whose character united all the elements of success in practical opera- tions, — took up the task that it became in any degree a commercial success. Very little is kno\vn in detail of the experiments or of the constructions of the Marquis of Worcester ; and that absorbing romance by George Macdonald, "St. George and St. Michael," may perhaps be taken as quite as. authoritative as any biography, so far as such minor details are concerned ; but the work of Savery, nearly a half-century later, came within the range of modern history, and is well understood. When Savery took up the new problem, at the lO ROBERT FULTON. opening of the eighteenth century, the mines of Great Britain had become, in many instances, so deep that the labour of freeing them from water was an enor- mously difficult and expensive task with the means and apparatus at the disposition of the mine- owners. They had rude forms of pump worked by horse-power almost exclusively ; and in the older and more exten- sive mines, hundreds of horses were sometimes kept at work, and the profits of mining were becoming daily less and less, and seemed likely to be soon ex- tinguished by this great tax on production. Worces- ter and his contemporaries had seen this threatening outlook, and were apprehensive that Britain might soon lose that supremacy, industrially, which she had, in consequence of her success in mining, up to that time so firmly held. They had, in many cases, looked to steam or some as yet undiscovered motor to do this work more cheaply than horse-power ; but even Worcester and Morland failed to make practically useful application of the new "fire-engine." Savery, familiar with the business of mining, a mechanic by experience and practice as well as by nature, not only saw the opportunity, but saw also a way to secure a prize. He made a workmanlike reproduction of the Worcester machine, giving it a form capable of im- mediate and effective application to the intended pur- pose. This is his device, as built by him for mines, and as described by him to the Royal Society, then already (1698) formed and in operation, and to the public through his little book, " The Miner's Friend ; or, A Description of an Engine to raise Water by STEAM IN EARLIER TIMES. II Fire described, and the Manner of fixing it in Mines, with an Account of the several Uses it is apph- cable to, and an Answer to the Objections against it. Printed in London in 1702 for S. Crouch." It was Fig. 2. — Savery's Engine, A. d. 1702. distributed among the proprietors and managers of mines, who were then finding the flow of water at depths so great as, in some cases, to bar further progress. The engraving of the engine was reproduced, with the description, in Harris's " Lexicon Technicum," 12 ROBERT FULTON. 1704; in Switzer's ''Hydrostatics," 1729; and in Desagulier's "Experimental Philosophy," 1744.-^ In Figure 2, ZZ is the boiler in which steam is raised, and through the pipes O O '\\. is alternately let into the vessels PP. Suppose it to pass into the left- hand vessel first. The valve M being closed, and r being opened, the water contained in P is driven out and up the pipe S to the desired height, where it is discharged. The valve r is then closed, and the valve in the pipe O; the valve J/ is next opened, and con- densing water is turned upon the exterior of P by the cock Y, leading water from the cistern X. As the steam contained in P is condensed, forming a vacuum there, a fresh charge of water is driven by atmospheric pressure up the pipe T. Meantime, steam from the boiler has been let into the right-hand vessel Pp, the cock W having been first closed, and R opened. The charge of water is driven out through the lower pipe and the cock R, and up the pipe S as before, while the other vessel is refilling preparatory to acting in its turn. The two vessels are thus alternately charged and discharged, as long as is necessary. Savery's method of supplying his boiler with water was as follows : — The small boiler, D, is filled with water from any convenient source, as from the stand-pipe, S. A fire is then built under it, and when the pressure of steam in D becomes greater than in the main boiler, Z, a communication is opened between their lower ends, 1 Our illustration is from Thurston's " History of the Steam- Engine," p, 37. New York. D. Appleton & Co. STEAM IN EARLIER TIMES. 13 and the water passes, under pressure, from the smaller to the larger boiler, which is thus "fed" without in- terrupting the work. G and N are gauge-cocks, by which the height of water in the boilers is determined ; they were first adopted by Savery. " Here we find, therefore, the first really practicable and commercially valuable steam-engine. Thomas Savery is entitled to the credit of having been the first to introduce a machine in which the power of heat, acting through the medium of steam, was rendered generally useful. It will be noticed that Savery, like the Marquis of Worcester, used a boiler separate from the water- reservoir. He added to the * water-com- manding engine ' of the marquis the system of sur- face-condensation, by which he was enabled to charge his vessels when it became necessary to refill them ; and added, also, the secondary boiler, which enabled him to supply the working-boiler with water without interrupting its action. The machine was thus made capable of working uninterruptedly for a period of time only Hmited by its own decay. Savery never fitted his boilers with safety-valves, although it was done later by others j and in deep mines he was compelled to make use of higher pressures than his rudely- constructed boilers could safely bear." ^ In this case, we find an illustration of a very com- mon fact in the history of inventions : The originator of this machine was probably, perhaps undoubtedly, 1 Thurston's History of the Steam-Engine, p. 38. See, also, Thurston's Manual of Steara-Boilers. New York. J. Wiley & Sons. T4 ROBERT FULTON. the second Marquis of Worcester ; but the practical constructor^ and the finally successful inventor, was Savery, the man who combined inventive with con- structive power and business ability in that way which is almost always essential to complete success. Savery was more an " exploiter " of this invention than its author. Yet he did introduce some excellent modifi- cations of details, and the various practically useftil minutiae which so often are the prime requisite to commercially satisfactory work. A glance at the draw- ings of the machine, however, and a comparison with the modern steam-engine will show that this was not only not a steam-engine in the usual sense, a train of mechanism, but that it belongs to an entirely different class of apparatus. A real steam-engine was only in- vented after experience with the Savery apparatus had shown it to be a wasteful, dangerous, and compara- tively rude contrivance for the application of steam to the work of raising water. It was w^asteful in conse- quence of the fact that it applied the pressure of the steam at tne surface of the cold water to be raised, and was thus certain to condense much more than it could usefully employ ; it was dangerous in conse- quence of the fact that it must necessarily use pres- sures exceeding those of^ head of water to be encountered, and higher than the mechanics of that time could make their boilers and "forcing- vessels " capable of safely withstanding. More than one explosion actually occurred. It is here that we meet with perhaps the greatest of all the inventors of the steam-engine, — the man who STEAM IN EARLIER TIMES. 15 for the first time produced a steam-engine of the modem type j a train of mechanism, in which a steam- engine was constructed and applied to another ma- chine for the purpose of acting as its " prime mov^er," — an engine operating a pump. This greatest of the whole line of inventors, considered from the point of view of the historian of the engine and the student of its philosophy, was, not Watt, but Newcomen, or per- haps more precisely, two mechanics, Thomas New- comen and John Galley or Cawley, who patented the new engine, 1705, soon after Savery's machine had come to be fairly well known. Savery also controlled some of the patents incorporated in the new arrange- ment, and took an interest with its inventors, and shared their profits. Newcomen's engine, by employing steam of low, hardly more than atmospheric, pressure, evaded the dangers inherent in that of Savery, and by applying the steam to move a piston in a cylinder apart from the pump, secured comparatively economical perform- ance. It promptly displaced the older and ruder contrivance, and came into use all over Europe, as constructed later by Smeaton and other great engi- neers of the day. As finally given form by these able men, it isiseen in the next engraving, which* shows the machine as built by Smeaton in 1774, for the Long Benton colhery.^ The boiler is not shown in the sketch. Figure 3 illustrates its characteristic features.^ 1 History of the Steam-Engine, p. 65. 2 A fac-simile of a sketch in Galloway's " On the Steam- Engine," etc. i6 ROBERT FULTON. The steam is led to the engine through the pipe, C, and is regulated by turning the cock in the receiver, D, which connects with the steam- cylinder by the pipe, E, which latter pipe rises a little way above the \ ' i ) i S ly^^!^; ^1 Fig. 3. — Smeaton's Newcomen Engine. bottom of the cylinder, i% in order that it may not drain off the injection- water into the steam- pipe and receiver. The steam-cylinder, about 10 ft. (3 m.) in length, is fitted with a carefully-made piston, G, having STEAM IN EARLIER TIMES, 1 7 a flanch rising 4 or 5 inches (.1 to r.25 m.) and extending completely around its circumference, and nearly in contact with the interior surface of the cylinder. Between this flanch and the cylinder is driven a *^ packing " of oakum, which is held in place by weights \ this prevents the leakage of air, water, or steam past the piston, as it rises and falls in the cylinder at each stroke of the engine. The chain and piston-rod connect the piston to the beam //. The arch-heads at each end of the beam keep the chains of the piston-rod and the pump-rods perpen- dicular and in line. A "jack-head" pump, N^ is driven by a small beam deriving its motion from the plug-rod at g^ raises the water required for condensing the steam, and keeps the cistern, (9, suppHed. This "jack- head " cistern is sufficiently elevated to give the water entering the cylinder the velocity requisite to secure prompt condensation, K waste-pipe carries away any surplus water. The injection- water is led from the cistern by the pipe, P P, which is two or three inches in diameter; and the flow of water is regulated by the injection-cock, r. The cap at the end, d, is pierced with several holes, and the stream thus divided rises in jets when admitted, and, striking the lower side of the piston, the spray thus produced very rapidly condenses the steam, and produces a vacuum beneath the piston. The valve, e, on the upper end of the injection-pipe, is a check-valve to prevent leakage into the engine when the latter is not in operation. The little pipe, /, supplies water to the 2 i8 . ROBERT FULTOJV. Upper side of the piston, and, keeping it flooded, pre- vents the entrance of air when the packing is not perfectly tight. The " working-plug," or plug-rod, Q^ is a piece of timber slit vertically, and carrying pins which engage the handles of the valves, opening and closing them at the proper times. The steam-cock, or regulator, has a handle, h, by which it is moved. The iron rod, / /, or spanner, gives motion to the handle, h. The vibrating lever, k /, called the Y or the " tum- bling bob," moves on the pins, in n, and is worked by the levers, op, which in turn are moved by the plug- tree. When o is depressed, the loaded end, k, is given the position seen in the sketch, and the leg, / of the Y strikes the spanner, / /, and, opening the steam-valve, the piston at once rises as steam enters the cylinder, until another pin on the plug-rod raises the piece, P, and closes the regulator again. The lever, q r, connects with the injection-cock, and is moved, when, as the piston rises, the end, q, is struck by a pin on the plug-rod, and the cock is opened and a vacuum produced. The cock is closed on the descent of the plug-tree with the piston. An educ- tion-pipe, R, fitted with a clock, conveys away the water in the cylinder at the end of each down-stroke ; the water thus removed is collected in the hot-well, S, and is used as feed-water for the boiler, to which it is conveyed by the pipe T. At each down-stroke, while the water passes out through R, the air which may have collected in the cylinder is driven out through the " snifting-valve," s. The steam-cylmder STEAM IN EARLIER TIMES. 19 is supported on strong beams, / // it has around its upper edge a guard, v, of lead, which prevents the overflow of the water on the top of the piston. The excess of this water flows away to the hot-well through the pipe W. Catch-pins, x, are provided, to prevent the beam descending too far should the engine make too long a stroke ; two wooden springs, y y, receive the blow. The great beam is carried on sectors, z z^ to diminish losses by friction. Comparing this machine wi^ that of Savery, it is seen that the dangers of the form previously in use are here evaded, while economy is enormously pro- moted by the change. As it is here practicable to employ steam of but slightly more than atmospheric pressure, no danger of explosions consequent upon high pressure in regular working is encountered. By the separation of the pump from the working cylin- der, and the application of the steam to a piston, instead of to a surface of cold water, the immense condensation to which it was subjected in the Savery engine is largely reduced. Thus both safety and economy are gained. It is therefore not at all sur- prising that this new invention should have come immediately into general use, and should have promptly become the standard form of the steam- engine for its time. It was built not only for all the principal mines of Great Britain, but also for those of the cotitinent of Europe ; and long after the death of its inventors the genius of that greatest of en- gineers of his time, Smeaton, continued to sustain it 20 ROBERT FULTON. and to keep it in use, even as a rival of the most famous of this whole Ime of inventions, — that of James Watt, who now comes upon the scene. Smea- ton himself built a large number of these engines; and at the time of his death, about the end of the eighteenth century, there were not less than a hun- dred Newcomen engines in Great Britain, and many elsewhere in Europe. Notwithstanding the great advantage possessed by this engine when compared with that of Savery, it was, compared with our modern standards, a very wasteful machine. Its wastes occurred through the same causes precisely as those operating in the case of its predecessor, and though in less degree, still to a very serious extent. In the operation of the pump-end it had become efficient ; but the steam-cylinder was both a power-producing mech- anism and a condenser of steam, — for the condensa- tion of the one working- charge was produced by the introduction of water, cooling the cylinder itself, as well as the steam which it contained. This cooling compelled a subsequent heating by the next charge of steam, and consequent condensation and waste proportional to the quantity thus demanded, — a very large fraction of all entering the engine. Its "duty" was about six millions of pounds of water raised one foot high by a bushel of coals, — the usual measure of efficiency of engines in those days. This was but about a quarter of that obtained a little later by Watt, and but a tenth of that secured ultimately by his best engines. It was about five per cent of what is JAMES WATT. 2i to-day considered the maximum duty of the modern engine of the best type. It is to James Watt that we owe the latest and crowning improvements of the steam-engine, as we know it to-day. A half-century after Newcomen he found among the collections of the then and still celebrated University of Glasgow — always famous for its success in the promotion of the physical sci- ences — a model of the still-used engine of that ear- lier and no less deserving inventor. He was, in the course of his duty as the instrument-maker to the college, called upon to put this little machine in re- pair ; and having done so, he became interested in studying its working. He was surprised to find that its steam- cylinder absorbed, each stroke, four times as much steam as its measurement would indicate to be possible, three fourths of that entering being evi- dently condensed, and only one fourth doing work. This waste of seventy-five per cent of all the steam supplied, and of a similar proportion of the fuel used in generating it, and of the money demanded for the operation of the engine, seemed so extraordinary that the active mind of the great inventor was at once applied to remedy so singular and immense a loss. Watt saw at once that the remedy must consist in some way of reducing this liquefaction of the steam by, as he said, " keeping the steam-cylinder as hot as the steam entering it." This he did by first effecting the condensation of the steam in a separate con- denser, instead of in the cylinder ; then surrounding the cylinder itself by a " steam-jacket," in which he 22 ROBERT FULTOiY. kept steam at boiler-pressure, thus preventing any cooling off of the engine during the period of its operation. In his patent of 1769, he says, — " My method of lessening the consumption of steam, and consequently fuel, in fire-engines, consists in the following principles : — " I St. That the vessel in which the powers of steam are to be employed to work the engine — which is called ' the cylinder ' in common fire-engines, and which I call '■ the steam-vessel ' — must, during the whole time that the engine is at work, be kept as hot as the steam which enters it : first, by inclosing it in a case of wood, or any other materials that trans- mit heat slowly; secondly, by surrounding it with steam or other heated bodies ; and thirdly, by suffer- ing neither water nor other substances colder than the steam to enter or touch it during that time. " 2dly. In engines that are to be worked, wholly or partially, by condensation of steam, the steam is to be condensed in vessels distinct from the steam- vessel or cylinder, though occasionally communi- cating with them. These vessels I call condensers ; and while the engines are working, these condensers ought at least to be kept as cold as the air in the neighbourhood of the engines, by application of water or other cold bodies. " Sdly. Whatever air or other elastic vapour is not condensed by the cold of the condenser, and may im- pede the working of the engine, is to be drawn out of the steam-vessels or condensers by means of pumps, wrought by the engines themselves, or otherwise. JAMES WATT. 23 "4thly. I intend in many cases to employ the expansive force of steam to press on the pistons, or whatever may be used instead of them, in the same manner as the pressure of the atmosphere is now employed in common fire-engines. In cases where cold water cannot be had in plenty, the engines may be wrought by this force of steam only, by discharging the steam into the open air after it has done its office." Thus he converted the " atmospheric engine " of Newcomen into the steam-engine of James Watt. His separate condenser, with its air-pump ; his cov- ered cylinder, permitting the contact of hot steam instead of cold air with the top of the piston; his steam-jacket, and his generally improved construction, at once gave him a machine which was capable of doing four times as much work, on the same expen- diture of money for fuel, as the older engine. A capitalist, Matthew Boulton, joined with Watt in the formation of a company for the manufacture of the new engine ; and the firm of Boulton and Watt became promptly known all over the civilized world, and is likely to be remembered as long as the steam-engine endures. This partnership was formed in 1769, and from that time on, for years. Watt found employment for all his genius in the improvement and adaptation of the engine for its countless purposes. In 1 78 1 Watt invented the now familiar "double- acting " engine, applied to turning a shaft, and to the driving of machinery in factories and mills. His patent included, — (i) The expansion of steam, and six methods of 24 ROBERT FULTON. applpng the principle and of equalizing the expansive power. (2) The double-acting steam-engine, in which the steam acts on each side the piston alternately, the opposite side being in communication with the con- denser. (3) The double or coupled steam-engine, — two engines capable of working together, or indepen- dently, as may be desired. (4) The use of a rack on the piston-rod, working into a sector on the end of the beam, thus securing a perfect rectilinear motion of the rod. {5) A rotary engine, or " steam-wheel." The efficiency to be secured by the expansion of steam had long been known to Watt, and he had conceived the idea of economizing some of that power, the waste of which was so plainly indicated by the violent rushing of the exhaust-steam into the condenser, as early as 1 769. This was described in a letter to Dr. Small, of Birmingham, in May of that year ; and the earlier Soho engines were, as Watt said, made with cylinders " double the size wanted, and cut off the steam at half- stroke." But though " this was a great saving of steam, so long as the valves remained as at first," the builders were so constantly annoyed by alterations of the valves by proprietors and their engineers that they finally gave up that method of working, hoping ultimately to be able to resume it when workmen of greater intelligence and reliability could be found. The patent was issued July 17, 1782.1 * History of the Steam-Engine, p. 105. JAMES WATT. 25 During the following two years or more, Watt was engaged in bringing out and perfecting a number of the minor inventions, the accessories of the engine, — as the governor, the counter, the numerous little details of construction and of valve mechanism ; finally, in 1784, he patented a group which included these, and the steam-hammer, and the locomotive. The steam- engine had now taken its distinctively modern form, and may be said to have been substantially com- pleted ; and Watt's work was mainly done. The form of the engine as now built by the firm is seen in the next engraving, which is a reproduction of his own drawings made at that date. In Figure 4, C is the steam-cylinder, P the piston, connected to the beam by the link, g, and guided by the parallel motion ^^