Dictionary of National Biography, 1885-1900/Watt, James (1736-1819)
WATT, JAMES (1736–1819), engineer, born at Greenock on 19 Jan. 1736, was grandson of Thomas Watt (1642–1734), a teacher of mathematics, surveying, and navigation at Crawfordsdyke, near Greenock. The father, James Watt (1698–1782) of Greenock, appears to have been a man of many pursuits: carpenter and joiner, builder and contractor, mathematical instrument maker—to some extent at least (for it appears he ‘touched’ compass needles)—a shipowner, and a merchant. This last calling is that by which he is described in certain of the town papers, and this is the calling stated on the tombstone erected by his son, James Watt, in 1808. He was much respected and esteemed, and in 1751 was made chief magistrate of Greenock. He died in 1782, in his eighty-fourth year. About 1728 he had married Agnes Muirhead; she appears to have been a most exemplary and devoted wife and mother. Prior to the birth of James, the engineer, she had sustained the loss of two sons and an only daughter, who died in infancy; three years afterwards another son, John Watt, was born, who died at sea in 1763, at the age of twenty-four. The mother predeceased her husband in 1755, at the age of fifty-two.
James Watt, the son, was always delicate, and suffered throughout his life from severe attacks of headache. He lived with his parents till his eighteenth year. He was first sent to a school in Greenock, kept by one M'Adam, and was jeered at by his fellows as being dull and spiritless, a condition due, no doubt, to his feeble health. Subsequently, when thirteen years of age, he began to study geometry, and at once showed the greatest possible interest in the subject. He then went to the Greenock grammar school, where he acquired Latin and some Greek. During his boyhood he was a diligent worker in his father's shop so far as regards the making of models, and gave early evidence of his great manual dexterity and of his power to turn out delicate work. At the age of seventeen to eighteen he was sent to Glasgow to live with his mother's relatives, then to London to improve himself as a mathematical instrument maker, and with this object became an apprentice of John Morgan, philosophical instrument maker, of Finch Lane, Cornhill. He found, however, that the atmosphere of London was unsuited to one of his delicate health, and in less than a year he returned to Greenock. He did not stay there for any length of time, but went and settled in Glasgow, being then in his twenty-first year. He then endeavoured to open a shop, as mathematical instrument maker, in Glasgow, but was prevented by the Corporation of Hammermen, on the ground that he had not served a proper apprenticeship. It was at this juncture that one of his school friendships stood him in good stead. Watt had for his most intimate schoolfellow Andrew Anderson, whose elder brother, John Anderson (1726–1796) [q. v.], was professor of natural philosophy at Glasgow University. The heads of the university now came to Watt's assistance by appointing him mathematical instrument maker to the university, and by allowing him to establish a workshop within its precincts. Here Watt continued to work and to improve himself in various ways, and here he made the acquaintance of many eminent men, such as Joseph Black [q. v.], the discoverer of latent heat; Adam Smith [q. v.]; and John Robison [q. v.], professor of natural philosophy. Here also, in 1764 (when Watt was in his twenty-eighth year), occurred the well-known incident of the repair of the model of a Newcomen fire (steam) engine, belonging to the university, which had never acted properly, although it had been sent to London to be put in order by the celebrated mathematical instrument maker, Sisson. The poor performance of this model fixed Watt's thoughts on the question of the economy of steam, and laid the foundation of his first and greatest invention. Watt prosecuted this invention so far as his limited means would admit, but nothing on a working scale seems to have been done, until he entered into an arrangement with John Roebuck [q. v.], the founder of the Carron Works, to take a share in the invention, and an engine was made at Kinneil, near Linlithgow. But Roebuck fell into difficulties, and this engine does not seem to have excited much attention; nor did the invention develop in the manner that might have been expected.
Moreover, Watt became largely employed in making surveys and reports, in connection with canals, rivers, and harbours. He appears to have succeeded Smeaton in the position of engineering adviser to the Carron Foundry. Among the last of his engineering works of this character were an improvement of the harbour of his native place, Greenock, and a provision of water-works for that town. In 1768 Dr. Small introduced Watt to Matthew Boulton [q. v.], the founder of the Soho Engineering Works, near Birmingham. In 1769 Watt's invention was patented. In 1772 Roebuck failed, and Boulton offered to take a two-thirds share in Watt's engine patent, in lieu of a debt of 1,200l. In May 1774 Watt, discontented with his surveying and other work in Scotland, migrated to Birmingham, and early in 1775, being then thirty-eight or thirty-nine, he entered into partnership with Boulton at the Soho Works.
In 1786 Watt accompanied Boulton to Paris to consider proposals for the erection of steam engines in that country under an exclusive patent. Watt declined the French government's offer on the ground that the plan was contrary to England's interests. Among the French men of science who welcomed Watt with enthusiasm on the occasion was Berthollet, who communicated to Watt his newly discovered method of bleaching. It was through Watt that the new method was introduced into this country.
Watt retired from the firm of Boulton & Watt in 1800, Matthew Boulton going out at the same time, leaving the business to their sons, James Watt, junior, and Matthew Robison Boulton. After his retirement from Soho James Watt pursued at his residence, Heathfield Hall, near Birmingham, various inventions in the workshop which he had fitted up there. He also continued his interest in Greenock, and gave to this town a library in 1816. In 1819, on 25 Aug., Watt died at Heathfield, in his eighty-fourth year, and was buried in St. Mary's Church at Handsworth (now a suburb of Birmingham).
Watt married, in 1763, his cousin, Margaret Miller of Glasgow, who bore him two sons and two daughters. This lady died in childbirth in 1773. It would appear that one son and a daughter died in Watt's lifetime; the other son, James, is noticed below. In 1775 Watt married his second wife, Ann Macgregor, who survived him some thirteen years, dying in 1832. He had by her a son Gregory, who appears to have been a man of great ability in literary as well as in scientific pursuits. To Watt's great and enduring grief this son died of consumption in 1804, at the age of twenty-seven. There was also a daughter of the second marriage.
Most persons, of good standing and general information, if asked what they knew about ‘Watt,’ would probably say that he was the inventor of the steam engine. Those who at all study the subject, or are acquainted with mechanical matters, will at once agree that, great as were Watt's merits, they were the merits of an improver upon an existing machine—the fire engine—and were not those which attach to the original suggester of a novel principle of work. Solomon de Caus in 1616, the Marquis of Worcester in 1659 [see Somerset, Edward, second Marquis of Worcester], Sir Samuel Morland [q. v.] in 1661, and Denis Papin [q. v.] in 1690, had each of them proposed to raise water from one level to another, in various ways, by the use of steam. It is disputed as to whether any one of these four inventors ever put his ideas into practice. Following these inventors, however, came Thomas Savery [q. v.], who put his ideas of raising water by steam power into real use, and to a very considerable extent.
All the before-mentioned inventors employed the steam, not to drive an engine (as we understand that expression) to work a pump, but they applied it directly to the vessels into which the water to be raised came, either to cause a partially vacuous condition in such vessels, so as to allow the atmospheric pressure to drive the water up into them, or to press upon the surface of the water in the vessels, so as to expel the water up a rising main, to a height dependent upon the pressure above the atmosphere of the steam employed, or, as in Savery's invention, to raise water by a combination of these methods. In Papin's case, pistons were interposed between the surface of the water and the steam. But about 1710 Thomas Newcomen [q. v.], in conjunction with John Calley, invented a ‘fire engine’ which was in truth a steam engine, in the sense in which we now understand the expression; that is, by the agency of steam he caused certain portions of machinery to move, and he applied their motion to work other machines, i.e. pumps. There was not any patent taken out for this engine, but Newcomen and Calley associated themselves with Savery, presumably on account of the existence of Savery's patent, which in those days probably would be held to cover the doing of an act by a particular agent (steam) almost irrespective of the mode by which that agent was employed. Newcomen's engine comprised a vertical cylinder with a piston working within it, which, when it descended by the pressure of the atmosphere acting on the piston, pulled down the cylinder end of the great beam, the other end at the same time rising and raising the pump rods. There was, of course, the boiler to produce the steam, and the condensation of the steam to produce the partially vacuous condition below the piston. An interesting adaptation of the power of a Newcomen engine to produce rotary motion is to be found in the specification of Jonathan Hull's patent of 21 Dec. 1736, or, better still, in the pamphlet that he issued in 1737, where he proposes to apply the steam engine to paddle-wheel propulsion.
Before passing away from the Newcomen engine, it may be well to notice the admirable account given by Belidor, in his ‘Architecture Hydraulique’ (1739–53), of an engine of this construction which had been made in England and was erected in France at the colliery of Fresnes, near Condé. The description is accompanied with complete scale drawings, from which, at the present day, a reproduction of this engine could be made without the slightest difficulty. It will be found that the boiler is provided with the safety valve invented by Papin, and with an open-ended standpipe for the admission of the feed water; this latter arrangement should, at all events, have insured that the pressure never could have attained more than the intended amount, probably two pounds above the atmosphere; but the amusing precaution is taken of covering the top of the boiler with heavy masonry, not for the purpose of confining the heat, but for that of holding down the boiler top against the pressure within. The writer told the late Sir William Siemens this, and was informed by him that, until quite lately, a regulation existed in France making such loading of the boiler top obligatory—a provision, it need hardly be said, not only useless with boilers of the present day, working at several atmospheres pressure, but absolutely harmful, as providing a stock of missiles ready to be fired all over the place should the boiler burst. Except in the matter of better workmanship and of increase in dimensions, the ‘Newcomen’ engine, as applied to the very important purposes of pumping, had remained practically without improvement for the nearly fifty years intervening between 1720 and 1769, the date of Watt's first patent.
Allusion has already been made to the well-known incident of the entrusting to James Watt for repair the model of the Newcomen engine belonging to the university of Glasgow. It turned out that the model was not out of repair, in the ordinary sense of the word, for it had lately been put in order by a celebrated philosophical instrument maker in London; but it was found that, although the boiler appeared to be of ample size, having regard to the dimensions of the cylinder, it was incompetent to generate sufficient steam to supply the heavy demand.
Watt was very much struck by this large consumption of steam, and at once turned his powerful mind to the consideration of how it was that so large a quantity of steam was needed. He saw it was due to the cold water used to condense the steam being injected into the very steam cylinder itself, and being played into that cylinder until its walls were brought down to a temperature corresponding to the vacuous condition intended to be produced in it; that, therefore, the quantity of incoming steam needed to fill the cylinder to atmospheric pressure in the up-stroke was not merely that represented by the cubic contents of the cylinder, but was, in addition, that needed in the first instance to heat up the whole of the walls of the cylinder, and the piston, with the water packing on the top of it, to its own temperature, to very considerably heat up the water accumulated in the cylinder, and also to expel the liquid contents and the air at the ‘snifting valve.’ Watt estimated these sources of loss as demanding at least three times as much steam as would have been needed to fill the contents of the cylinder; and, in actual practice, with large engines, in after years, he based his remuneration upon one-third of the cost of the fuel saved. At this time, and for some years previously, Joseph Black had held the chair of chemistry in Glasgow University, and in the course of his experiments had made the discovery of latent heat; that is to say, he had proved that mere temperature capable of being appreciated by a thermometer was by itself no guide as to the heat which had to be communicated to bodies to occasion changes of condition. This important scientific fact was repeatedly enunciated by Black in his lectures. Although it appears Watt had not the leisure to attend these lectures, he nevertheless was cognisant of the discovery, and he pursued the investigations into latent heat in connection with steam; he also determined the relation between the bulks of steam and water at atmospheric pressure, at pressures less than the atmosphere, and, to some extent, at pressures above the atmosphere. In fact, he prepared himself, as a man of science, to deal with the problem of improvements in the steam engine in actual practice. The solution of this problem by Watt was to condense the steam, not in the cylinder itself, but in a separate vessel, in connection, however, with the cylinder at appropriate times. The jet of cold water was thus from henceforth for ever discarded from entering the steam cylinder.
With the early models constructed by Watt the separate vessel was composed of thin metal and was immersed in water; in other words, it was the ‘surface condenser.’ But subsequently, although as a rule the condenser continued to be immersed in water, the main reliance was no longer placed upon the cooling of the sides, but upon the use in the separate condenser of such an injection as had been employed by Newcomen in the steam cylinder itself. It must strike every one (of course it at once occurred to Watt) that in a very short time his condenser would be full of water from the condensed steam, mixed with the incondensable air liberated from the steam and from the condensing water, and that thus the vacuous condition would be speedily lost. The remedy for this was to apply an ordinary pump, to pump out the condensed steam, and also, where injection was used, the water of condensation and the air, and in this way the separate vessel was at all times maintained in a partially vacuous condition. As has already been said, Watt's want of means, and the need of pursuing other avocations for a livelihood, retarded the practical outcome of the invention for some time. Indeed, the want of means even prevented the application for a patent to secure the invention; for, although the discovery was made in 1765, the patent was not obtained until 1769 (No. 913). It does not appear that in the preparation of the specification Watt had the benefit of legal advice, but he had plenty of friendly philosophical advice. As a result of this amateur assistance the specification was so clumsily drawn that the validity of the patent was, many years afterwards, seriously contested. This patent not only included the separate condenser, with the air-pump, but it also embraced a variety of other matters. In the specification there is enunciated the doctrine which is as truly at the root of all engine economy at the present day as it was in the days of Watt—namely, that the walls of the cylinder should be maintained at the same heat as that of the steam which is about to enter the cylinder. Watt proposed to do this by means of an external casing, leaving an annular space between it and the outside of the cylinder, in which space there should always be steam, this external casing to be itself surrounded by some non-conductor. It should have been stated that Watt experimented with wooden cylinders, hoping that the non-conducting character of that material would have diminished condensation; but he found that such cylinders could not resist the continued action of the steam. This 1769 patent covered, as has been said, several heads of invention. The fifth head was for a rotary engine, of which the description was of the very haziest, and, as there were not any drawings attached to the specification of this patent, it would have been impossible from the information afforded by it for any workman to have constructed such a machine; and even could he have made it, it would not have worked, as Watt found out after repeated trials. Another head of invention was to lower the pressure of the steam by cooling it to a point not sufficient to cause condensation, and then to reheat it. Neither of these inventions ever came into practical use, and it is certainly a matter of surprise that, in the actions which ensued upon this patent, objection was not taken to the absolute absence of explanation as regards the fifth head of invention, the rotary engine. With Roebuck's assistance an engine with the separate condenser and air-pump was actually erected at Kinneil. The cylinder was eighteen inches diameter. This engine was tried on several occasions, but with no thoroughly definite result.
Dr. Roebuck having got into financial difficulties, the progress of the engine was impeded until, fortunately for Watt and for the world, Roebuck and Dr. Small in 1767 brought about the connection between Watt and Boulton. Subsequently Roebuck surrendered, on a proper payment, his interest in Watt's invention. It was then agreed, as so many of the fourteen years' life of the patent had expired without any remunerative result whatever, to apply to parliament to obtain an extension. In 1775 this act, which extended the patent until 1800, was passed, and in the same year the partnership with Boulton was effected. The experimental engine was removed from Kinneil to Soho, and was there put to work in such a manner as to demonstrate the merit of Watt's invention.
Inquiries from owners of Cornish mines began to be made as to the provision of the new engines. A very considerable business developed gradually in Cornwall, involving Watt's living in that county for lengthened periods extending over several years. This appears to have been a time of great distress to Watt. He disliked the roughness of the people; he was averse from all bargaining; he was in his usual bad health; and was away from all the scientific society he loved. In the result a large number of the improved pumping engines were put up, and were paid for on the fuel-saving terms already stated; but, whatever may have been the hoped-for eventual profits, the immediate result was the locking up of a large amount of capital, and it demanded all Boulton's indomitable energy and the exercise of his admirable business talents to carry the partnership through the time of trial. This Boulton, however, successfully accomplished, and, what is more, he encouraged his partner Watt, faint-hearted in all commercial matters, to hold up against their troubles. On 16 April 1781 he wrote to Watt in Birmingham: ‘I cannot help recommending it to you to pray morning and evening, after the manner of your countrymen (the Scotch prayer “The Lord grant us a gude conceit of ourselves”), for you want nothing but a good opinion and confidence in yourself and good health.’ It should have been stated that in the ‘Watt’ engine a cover was placed over the cylinder, the piston-rod working through a stuffing-box, and that the steam was at all times admitted to the upper side of the piston, its pressure replacing that of the atmosphere when the downward or working stroke of the piston was made, at which time the bottom of the cylinder was in connection with the condenser; that when the return stroke was to be made the condenser was shut off by an appropriate valve, and that another valve, called an ‘equilibrium valve,’ was opened, thereby establishing a connection between the upper and the under side of the piston, which, being then in equilibrium, could be drawn up by a counter-weight. Thus far the improved engine, like its predecessor (Newcomen's), was applied practically only for the raising of water; and where, as was so commonly the case, rotary motion was needed, recourse was had, if the work were beyond the power of horse gear, to the employment of a water-wheel to be driven by the water pumped by the engine. This was obviously an unsatisfactory operation, involving the cost of extra plant—plant demanding a considerable space—and involving also the diminished output of work due to the losses in the intermediate machine, the water-wheel. Watt therefore applied himself to obtain rotary motion from his reciprocating engine. The engine, being single-acting, did not lend itself well to the purpose; but it could be made to perform, to a considerable extent, as though it were double-acting by the expedient of largely increasing the counter-weight until it was equivalent to about one-half the total raising power of the piston. Watt applied himself to produce direct rotary motion from such a reciprocating engine. It is stated that he intended to obtain this end by the use of the crank, and was preparing to patent its application, but that, while the matter was under consideration, one Pickard, a workman in Watt's employ, revealed the secret to a man of the name of Wasbrough of Bristol, who was endeavouring to obtain rotary motion by various complex contrivances, which he made the subject of a patent of 1779 (No. 1213); that these being unsuccessful he joined himself to Pickard, who in 1780 took a patent (No. 1263) for the use of the crank in the steam engine. Watt was seriously inconsistent in his observations on this crank question, and his biographers—or some of them—have allowed themselves to follow him in his inconsistency; for while on the one hand he put himself forward as a meritorious inventor, and the intending patentee of the use of the crank, and complained bitterly of his invention having been stolen, on the other hand he writes in respect of Pickard's patent that ‘the true inventor of the crank rotative motion was the man who first contrived the common foot-lathe. Applying it to the engine was like taking a knife to cut cheese which had been made to cut bread.’ Thus Watt, while intending to patent the use of the crank, must in his own mind have known that such use was a mere ‘obvious application,’ and was therefore not capable of being made the subject of a valid patent. On finding that he was shut out by Pickard's patent from the use of the crank, Watt devoted himself to devising other means for converting a reciprocating into a rotary motion. He devised five different modes, the subject of his patent of 1781 (No. 1306), none of which, in his opinion, were amenable to the charge of involving the use of cranks; but there is no doubt that two of them were absolutely cranks. There does not appear to be any record of four of these devices having been used; but the fifth device, the ‘Sun-and-Planet’ wheel, was largely employed by Watt for converting the reciprocating motion into rotary motion.
Watt's engines, as actually made (the writer of this article remembers one of them perfectly), had the sun and the planet wheels of equal size, the planet being confined to its orbit by a link loose upon the sun-wheel shaft—the natural and proper means of doing it. But whether Watt feared that such a construction might be held to amount to a crank, or what other cause may have influenced him, cannot now be determined; but the fact is that in his specification he made a most extraordinary provision for confining the planet wheel to its orbit, by inserting a pin in continuation of the axis of the planet wheel, into a circular groove. The sun and planet wheels of the proportions used by Watt—that of equality of diameter—had a certain value besides that of steering clear of Pickard's patent, in that they gave two revolutions of the sun shaft, which was also the fly-wheel shaft, for each double reciprocation of the engine, so that the speed of a slow-going engine was at once augmented in the very engine itself, and, moreover, the fly-wheel had its value quadrupled. Some attempt was made to agree with Pickard for the use of the crank; but Watt's pride revolted from buying back that which he said was his own invention, and he explains that he had no wish to destroy Pickard's patent, thus throwing the use of the crank open to the public, and depreciating therefore the value of Watt's own substitute, the sun and planet.
Up to the present time it will have been noticed that, in all cases of Watt's engines, there was only one working stroke made during the passage to and fro of the piston in the cylinder, the return stroke being due to the action of a counter-weight. But, having now in these engines a close-topped cylinder with a piston-rod working through a stuffing-box, and having valves by which connection was made alternately between the under side of the piston and the steam boiler, and between the underside of the piston and condenser, it followed almost as a consequence that by additions to these valves the functions of the steam and vacuum might be repeated on the upper side of the piston, and that thus the engine would have a working stroke in both directions, rendering it independent of counterweights, and eminently adapting it for operation upon a crank, or upon its equivalent, to produce rotary motion. This was one of the subjects of Watt's patent of 1782 (No. 1321), and not only was this construction of great utility for giving comparative uniformity of rotary motion, but also it was one which obviously doubled the work that could be obtained out of a given dimension of cylinder. This patent also embraced another most important principle in the use of steam, one upon which practically the whole improvement, made since Watt's days to the present, in the economy of fuel depends—namely, the employment of steam expansively.
A few words of explanation to the non-technical reader may perhaps be necessary. Assume a cylinder of such a diameter as to have 1 square foot = 144 square inches of area, and assume the stroke of the piston in it to be 2 feet. Let steam be introduced into this at, say, two atmospheres of pressure, and assume the impossible, that there were a perfect vacuum in the condenser. Then, for simplicity, calling the atmosphere 15 lb. pressure, the piston would be urged to move by a load equal to 144 (2 × 15) = 4320 lb. And, if it did so through the 2-feet stroke, it would give a work of 8640 foot lb. and the consumption of steam would be 2 cubic feet at 2 atmospheres density. Assume, now, that, instead of allowing the steam to escape when the piston had completed the 2-feet stroke, the cylinder could be extended to a total length of 4 feet. Then the same steam—the ingress of any further quantity being cut off—continuing to press on the piston (the vacuous condition being maintained on the other side), the piston would be urged to move with a gradually decreasing pressure throughout the remaining two feet; and that, at the end of its journey, the steam being then double in volume, would still have a pressure equal to one atmosphere. The mean pressure throughout this second 2 feet would be 20.8 lb. then 144 × 20.8 × 2 feet equals another 5,990 foot-pounds obtained without the expenditure of any more steam. Thus, in the first supposed instance of non-expansion, 2 cubic feet of steam at 2 atmospheres density would produce 8,640 foot-pounds of work, while the same steam expanding to twice its bulk would produce 14,630 foot-pounds, or 69 per cent. more. It will of course be understood that these are merely illustrative figures, subject in practice to large deductions, the causes of which cannot be gone into here. As long as the engines were single-acting and the connection between the piston-rod and the beam was one that was always exposed to a tensile strain, that connection could well be made by means of a chain working over a sector attached to the beam. But so soon as the engines were made double-acting, then the piston-rod had no longer only to pull the beam end down, but had also to push it up. This was an operation which obviously could not be carried out by a single chain. To overcome this difficulty, and still by the use of a chain, a contrivance was invented which prolonged the piston-rod high up, and a second chain connected to the bottom end of the sector was employed; so that while the old chain pulled the beam end down, the new chain pulled it up.
Another contrivance was to furnish the sector with teeth and to provide the piston-rod with a rack engaging in these teeth. Both these arrangements were unsatisfactory. The remedy was to place a link jointed at its lower end to the top of the piston-rod and at its upper end to the beam. It is clear that, having regard to the versed sine of the arc described by the beam end, this link would be deflected out of the upright, and thus the piston-rod top would be exposed to a resultant horizontal stress, tending to deflect it. The obvious way to have overcome this tendency was to furnish the ends of the pins of the piston-rod with guide-blocks working in or on vertical guides, and Watt in his patent of 1784 (No. 1432) specifies this as one means of attaining his end. But he devised another, and a most elegant mode, whereby advantage was taken of the reverse curve given by levers pivoted in opposite directions so that the moving ends of these levers being united by a link, a point would be found in that link which for the extent of stroke required in the engine would move in a path that did not harmfully deviate from a straight line. This is Watt's celebrated parallel motion, on which he prided himself more than on any of his other inventions, and it is still used in nearly all the beam-engines that are now manufactured in the United Kingdom. But in the large number of direct-acting engines, embracing as they do in these days all steam vessels and all locomotives, transverse stresses of a more serious character—namely, those given by the crank through the connecting rod—are successfully combated by the simple guide which Watt rejected in practice for the parallel motion with which he was so very much pleased. Among Watt's other contrivances to obtain a connection between the piston-rod and the beam was the employment of a hollow or trunk piston-rod having the pin of the lower end of the connecting link situated at the lower part of the rod just above the piston.
Watt's many and most valuable inventions must always place him among the leading benefactors of mankind, and there can therefore be no need to endeavour to augment his merits by attributing to him, as some of his biographers have done, matters which were not really of his invention, although used by him. One instance is that of the centrifugal governor to regulate the speed of steam engines. It is commonly stated that Watt invented the centrifugal governor; but this is by no means certain, as it is frequently said that it had previously been used in flour-mills to control the distance apart of the millstones.
The writer has tried to find any publication prior to 1781, the date of Watt's patent for obtaining rotary motion from a reciprocating steam engine, which describes the use of the governor in flour-mills, but has not succeeded. The earliest publication he has as yet found is the specification of Thomas Mead's patent of 1787 (No. 1628), ‘Regulator for Wind and other Mills.’ A reader of this specification must certainly come to the conclusion that Mead was (or that he believed himself to be) the inventor of the implement, and not merely the suggester of its application to mills.
The writer has not been able to ascertain when Watt first applied the governor to his steam engines. Farey in his book on the steam engine, published in 1827, says, at p. 437: ‘In the years 1784 and 1785 Messrs. Boulton and Watt made several rotative engines … One of the first of these was set up at Mr. Whitbread's brewery in Chiswell Street … Mr. Whitbread's engine was set to work in 1785. In their general appearance these engines were very much like that represented in plate xi, having the same kind of parallel motion, sun and planet wheels, and governor.’ If this statement about the governor be correct, then Watt was using governors three years before the date of Mead's patent. It must, however, be remembered that Farey was writing between forty and fifty years after the period under consideration. At p. 435 Farey, describing the governor, says: ‘It was on the principle which had been previously used in wind and water mills.’
Having regard to Watt's silence on the question of the governor, to the fact that he did not patent it, nor even its application to the steam engine; having regard also to the statements (unsupported, it is true) of many writers that the implement was used as applied to flour-mills before the date of its application by Watt to the steam engine, it appears the probabilities are largely against Watt being the inventor of the governor. Watt applied it to the steam engine, and devised a particular kind of valve, the ‘throttle valve,’ which, being balanced on each side of a central spindle, was capable of being moved by a comparatively weak agent, such as the centrifugal governor.
There is another very useful adjunct to the steam engine—the indicator—the whole invention of which is also commonly but erroneously attributed to Watt. The indicator is an implement by which a pencil, controlled by a spring, is made to move forwards or backwards in accordance with the pressure prevailing in the engine cylinder at any moment, while a card, or nowadays a paper, is caused to traverse transversely to the movement of the pencil, and thus there is drawn on the card by the pencil, a diagram, which shows and records the varying pressures in the cylinder at all parts of the stroke of the piston, and thus enables the work done on the piston and the quantity of steam used to be determined. No doubt this implement has been of the greatest value in the developing of the various improvements which have been made, and are still going on, in the steam engines. Watt's share in the invention of the indicator was confined to the simple and comparatively useless vertical motion of the pencil in accordance with the pressure in the cylinder, and was a mere substitution for a glass tube containing mercury; the transverse motion, by which alone the diagram could be obtained, was due, it is believed, to the genius of John Southern, one of Boulton & Watt's assistants. So long as steam engines were used only for raising water, it was extremely easy to state the amount of work they were doing and to compare one engine with another. Thus, if engine A were raising a hundred gallons per minute from a depth of a hundred fathoms, and engine B were raising two hundred gallons from the same depth, B was obviously doing double the work of A; but when engines were employed to drive mill-work, there was no such record of ‘work done’ obtainable; it became necessary, therefore, to devise some standard. Prior to the use of the steam engine rotary motion on the large scale was derived from water-wheels, and on a small scale from windmills or from horse-wheels. Watt therefore, following Savery, determined that the horse-power should be the standard. Savery had come to the conclusion that it would need a stock of three horses to provide one always at work. He does not appear to have determined the ‘work’ of a horse; but if there were required four horses at work to drive, say, a pump, and Savery made an engine competent to do the same duty, he called that a 12-horse engine, as it was equivalent to the twelve horses that needed to be kept to provide four horses always at work. Watt, however, did not follow Savery in his rule-of-thumb determination, nor did he credit his engine with the idle horses. He satisfied himself that an average horse could continue to work for several hours when exerting himself to such an extent as would raise 1 cwt. to a height of 196 feet in a minute, equal to 22,000 lb. one foot high. In order that a purchaser of one of his engines should have no ground of complaint, he proportioned these machines so that for each of his horse-powers they should raise half as much again, or 33,000 lb. one foot high per minute. As regards the confusion into which the question of horse-power drifted, resulting in as many as five different kinds, see the ‘Proceedings of the Royal Agricultural Society’ (2nd ser. vol. ix. Cardiff meeting, No. 17, p. 55).
In 1785 Watt took out his last patent, No. 1485. This was for constructing furnaces, &c., the object being to attain better combustion and the avoidance of smoke. The invention appears to have been based on correct principles, and to have been employed with success to some little extent; but it was dependent very largely on the attention of the stoker, and was of but little practical use.
It has been thought well not to interrupt the sequence of the engine patents, and thus a patent as early as 1780 (No. 1244) has been passed over in order of its date, as it related to a matter entirely unconnected with the steam engine; it was, however, of great utility, and is now universally employed. This was the invention of copying letters by means of a specially prepared ink, which would give an impression on a damped sheet of a suitable paper when the writing and the damped paper were pressed together. Probably but few of the thousands upon thousands who, throughout all civilised nations, have their letter-copying books and presses are aware that this most useful process is due to the great James Watt.
When the success of the Watt engine was fully established, attempts were made to invent engines which should have the same advantages, but which should not be within the ambit of Watt's patent. One of these attempts was by Edward Bull, in the case of pumping engines for mines. The sole alteration he made was to invert the cylinder over the shaft of the mine and to connect the pumps directly to the piston-rod, thus doing away with the main beam; but he retained the separate condenser with its air-pump. Another attempt was made by Jonathan Carter Hornblower [see under Hornblower, Jonathan]. He proposed to employ the expansive principle by allowing the steam to pass from one working cylinder to a second working cylinder of increased capacity—a construction which prevails to-day under the title of the compound engine, and that, in the further development of three cylinders in series, is practically universally employed in all large steam vessels, whether used for war or for commerce. Hornblower, however, could not dispense with the separate condenser and air-pump, and his engines were thus infringements of Watt's original patent. From 1792 to 1800 Watt and his partner were engaged in vindicating his patent, and in putting a stop to these infringements. Actions were brought in the common pleas against Bull and against Hornblower, with whom was joined as defendant one Maberley. In each case the infringement was all but admitted, the defenders' arguments being addressed to the invalidity of the patent. In each case the jury found a verdict for the plaintiff. In each case the full court of common pleas by a majority determined the patent to be bad, on (speaking as a layman) grounds of the vagueness of the specification, due to the advice of the amateurs in patent matters to whom allusion has already been made, and in each case there was appeal. On appeal the patent was upheld, and the long litigation came to an end, after years of anxiety suffered by Watt and his partner, and after very heavy expenditure, as may be gathered from the fact that in the four years between 1796 and 1800 the costs were 6,000l. Watt used to speak of his patent as ‘his well-tried friend.’
By the kindness of Mr. George Tangye of Soho and of Heathfield Hall (at one time Watt's residence), the writer has had access to much of the correspondence between Boulton and Watt and their sons during the period these actions were going on; it is most interesting, and it shows also the charming character of the relations subsisting between these four men. In April 1781 Boulton, after complaining to Watt of a difference he had with a partner in his separate business, continued: ‘However, as to you and I [sic], I am sure it is impossible we can disagree in the settling of our accounts, as there is no sum total in any of them that I value so much as I do your esteem, and the promotion of your health and happiness; therefore I will not raise a single objection to anything that you shall think just, as I have a most implicit confidence in your honour.’
Watt's love of science was not confined to physics. He had from the time of his early life in Glasgow been devoted to chemistry, and, when settled in Birmingham, the pursuit of chemical science was stimulated by his intimate connection with such men as Priestley, Keir, Small, and Wedgwood. These, with others, constituted the ‘Lunar’ Society, who met monthly at about the time of the full moon. It was no doubt his steady pursuit of chemical science, even in the midst of all his steam-engine labours, that led Watt to the brilliant discovery of the composition of water. That Watt did make this independent discovery is undoubted. Whether it was made prior to a similar discovery by Henry Cavendish (1731–1810) [q. v.] is a question about which there has been much and bitter controversy. It seems clear, however, that Watt, as early as 13 Dec. 1782, wrote to Jean André Deluc [q. v.], ‘I believe air is generated from water. … If this process contains no deception, here is an effectual account of many phenomena, and one element dismissed from the list.’ Later on, 26 April 1783, Watt wrote to Dr. Priestley a letter setting forth his discovery of the composition of water, and requesting that it might be given to Sir Joseph Banks, then president of the Royal Society, with a view to its being read at a meeting. Owing to Priestley's doubts, Watt requested that the reading should be delayed to ascertain the result of some experiments Priestley said he was about to make; it further appears that in the meanwhile Watt's paper was pretty freely shown among the leading members of the society. On 26 Nov. 1783 Watt wrote a letter to Deluc on the same subject; this letter was not read to the society until 29 April 1784; while Cavendish's communication on the same subject was read on 15 Jan. 1784. Lord Brougham traced out various interpolations in the ‘Philosophical Transactions’ in Cavendish's favour by Sir Charles Blagden [q. v.], then secretary; and a curious double misdating of these transactions was also found; making it appear that Watt's communication of 26 Nov. 1783 was 26 Nov. 1784, and that Cavendish's paper was of the date of 15 Jan. 1783, and not, as was the fact, of 15 Jan. 1784. On 22 April 1783 Watt, in writing to Gilbert Hamilton, made this declaration of faith: ‘Pure inflammable air is phlogiston itself.’ ‘Dephlogisticated air is water deprived of its phlogiston, and united to latent heat.’ ‘Water is dephlogisticated air deprived of part of its latent heat, and united to a large dose of phlogiston.’ Watt directs that one part by measure of ‘pure air’ ( = dephlogisticated air = oxygen) and two parts by measure of inflammable air ( = phlogiston = hydrogen) are to be mixed and fired. It is quite certain that Arago in his éloge of James Watt delivered in 1839, though thoroughly aware of the claims that had been put forward by the friends of Cavendish, unhesitatingly ascribed the first discovery of the fact that water was not an element, but was a compound body, and also the ascertaining the nature and proportion of the two constituents, to Watt.
Watt had his interest in chemical science still further stimulated by the hope of benefiting the health of his invalid son, Gregory, by the inhaling of gases, called in those days ‘factitious airs.’ This mode of cure was advocated by the celebrated Dr. Thomas Beddoes [q. v.], and Watt devised an apparatus to be used in hospitals, and of a smaller size in private houses, for the generation of the ‘airs,’ and in 1796 published a pamphlet, with illustrations, prices, and directions for use. Two principal ‘airs’ were to be produced, the one oxygen and the other hydro-carbonate; this appears to have been a mixture of hydrogen, carbonic acid, and some carbonic oxide. This horrible compound was not supposed to be of the best kind, nor to do its work properly, unless it had the effect of producing in the unhappy inhaler an attack of vertigo. Watt had advocated the employment of lime in the case of the oxygen gas to purify it, but he cautions the user of the apparatus when making the hydro-carbonate to be careful not to let any lime come in contact with the gas, as, if so, it will not produce the desired giddiness. The pamphlet is one of extreme interest, and the writer is indebted to Mr. George Tangye for a copy.
Watt fitted up a garret in Heathfield Hall as a workshop, and late in life returned to the practice of that delicate manual work in which he had always been so great a proficient. He specially devoted himself to the invention and constructing of apparatus for the copying and reproduction of sculpture, and he produced some very admirable specimens of this work, of which he was not a little proud. In 1883 there remained in this workshop a most interesting collection of models of several of Watt's inventions, including models of his various modes of obtaining rotary motion. They are most clearly described in a paper by Mr. E. A. Cowper, read before the Institution of Mechanical Engineers in November of that year. Now, practically the whole of these models have been removed, leaving only the sculpture copying machines.
Among the very interesting letters in the possession of Mr. George Tangye are some from Argand, on behalf of himself and of Montgolfier, relating to that most ingenious water-raising implement, the hydraulic ram, and to the Argand lamps. There are also four original letters from Robert Fulton to Boulton and Watt, ranging from 1794 to 1805, in which orders are given for steam engines, to be used in the steamboats Fulton was building.
Watt's first and greatest invention—condensation in a vessel separate from the steam cylinder—was the very life of steam engines working at the low pressure prevailing in those days, as such engines owed their power to the greater or less approach to a perfect vacuum which could be effected; but as the pressure of steam became increased, the value of the vacuous condition became relatively less and less, and thus the finality so confidently claimed by Mr. Serjeant Rous, in his speech to the court of appeal, was speedily shown to be groundless. Rous asserted, ‘This peculiar invention, for which this patent has been obtained, was from the first perfect and complete, has never been improved, and from the nature of things never can, because it is impossible to have more than all.’ So long ago as 1872, at the Cardiff meeting of the Royal Agricultural Society before mentioned, a portable non-condensing engine was shown, developing a horse-power for a consumption of 2.79 lb. of coal per hour.
It has always been a matter of surprise that Watt, who had invented the expansive use of steam, did not develop this principle by employing steam of higher and higher initial pressure; but this he did not do, and he steadily opposed Richard Trevithick [q. v.], who was the persistent advocate of high-pressure steam coupled with expansion. Sixteen years after Watt's death, when the writer of this article was an apprentice, the common pressure of steam in condensing engines, whether stationary or marine, was from 4 to 6 lb. per square inch above atmosphere; and notwithstanding the condensation in the separate vessel, the consumption of coal was from 5 to 8 lb. per horse-power per hour. The steam pressure in marine engines is now from 150 to 250 lb. (Perkins went as high as 500 lb.), and the consumption of coal is from 1½ to 2½ lb. per horse-power per hour.
In spite of his wretched health, Watt was one of the most determined and persistent of men; his courage, except in matters of finance, was of the highest. He very early acquired a knowledge of German and of Italian to enable him to read works on mechanics published in those languages, and he appears from his correspondence to have been a good French scholar. It has been said he was originally a mathematical instrument maker, and a workman of great delicacy of touch. In his early days at Glasgow, at the request of some friends, he made an organ of great beauty of tone, and he also made other musical instruments to oblige his friends, and not, it would appear, from a love of music; for in later years, when Southern applied for employment at Soho, Watt said: ‘I should be very glad to engage him for a drawer, provided he gives bond to give up music. Otherwise I am sure he will do no good, it being the source of idleness.’ In early days also Watt invented and sold a portable machine for drawing from nature in proper perspective.
In his chemical pursuits he not only devised the apparatus to manufacture the ‘factitious airs,’ but he invented a simple mode of ascertaining the specific gravity of fluids, by means of a tube terminating in two tubular legs, one of which was immersed in distilled water, the other in the liquid to be tested. A partial exhaustion of the single tube being made, the water and the liquid to be tested rose in the respective legs, and the differences in the height between that of the water and of the liquid under trial gave the specific gravity of this liquid as compared with the water. Watt also invented an admirable micrometer; and he perceived the value of weather records, and for nine years kept at Soho a most complete account, observing every day at eight in the morning, two in the afternoon, and eight in the evening the height of the barometer, the temperature, the hygrometer, the direction of the wind, the rainfall, and the general condition of the weather.
Reverting to engineering—Watt devised a locked-up automatic counter, to record the number of strokes made throughout lengthened periods by his pumping engines. He proposed, and included in his patent of 1784 (No. 1432), a steam carriage for common roads, with differential gear for use on hills. He also proposed the use of the screw propeller, which he called the ‘spiral oar,’ for navigation. He was, in truth, not a mere specialist devoted to one subject, but was of great general scientific learning, and was a happy instance of a man who based his inventions on scientific data, and proved them in the model form by aid of his rare manual dexterity.
As regards the favourable impression he made on those with whom he associated in his later life, and the extent and versatility of his information, nothing can more readily testify to this than the statement by Sir Walter Scott of his meeting with Watt in 1817, when Watt was in his eighty-second year (Scott erroneously says eighty-fifth); this is to be found in Scott's letter to ‘Captain Clutterbuck’ in ‘The Monastery’ (1851 edit., p. 42).
Watt was made a fellow of the Royal Society of Edinburgh in 1784, of the Royal Society of London in 1785, and an LL.D. Glasgow in 1806, and was everywhere recognised by men of science as one of the foremost among them. This was so not only in the United Kingdom, but on the continent. As early as 1781 the Russian ambassador wrote on behalf of the empress a most flattering letter, begging Watt to go to Russia, and to be the supreme director of mines, metallurgy, and ordnance castings in that country. Watt refused this offer in a letter admirable for its clearness and its courtesy. He corresponded very frequently with scientific men in France, and was extremely well received there by them when he went with Boulton to Paris in 1786. Lavoisier and Berthollet were among his most intimate acquaintances. In 1808 he was made a corresponding member of the Institute of France, and in 1814 one of the eight foreign associés of the Académie des Sciences. He declined shortly before his death an offer of a baronetcy made through Sir Joseph Banks.
On 18 June 1824 (rather less than five years after Watt's death) a public meeting was held in London to make provision for a monument to Watt's memory; this meeting was attended by (Sir) Humphry Davy, Sir Robert Peel, Lord Brougham, and many others. In the result, a monument by Chantrey was erected in Westminster Abbey, with an epitaph by Brougham; while in France, Arago in 1839 pronounced a well-known and appreciative éloge before the Académie des Sciences.
A bust of Watt by Chantrey, a medallion and a chalk drawing by Henning, and a sepia by George Dawe are in the National Portrait Gallery, Edinburgh. Two portraits, one painted by Charles F. de Breda in 1793, and the other by Henry Howard, R.A., are in the National Portrait Gallery, London. Sir William Beechey in 1801 and Sir Thomas Lawrence in 1813 painted half-lengths, and Sir Henry Raeburn a head in 1815. A large statue was erected in Birmingham in 1868, and there are full-length statues by Chantrey not only in Westminster Abbey but at Glasgow (both in George Square and at the college), in Greenock Library, and in Handsworth church, where the engineer was buried.
The son, James Watt (1769–1848), born on 5 Feb. 1769, early turned his attention to science. In 1789 he went to Paris to pursue his studies, and took part in the revolutionary movement. At first he was in high favour with the leaders, but on showing a distaste for their later excesses, he was denounced before the Jacobin Club by Robespierre and was compelled to flee into Italy. Returning to England in 1794, he became a partner in the Soho firm, and afterwards gave some assistance to Fulton. In 1817 he bought the Caledonia of 102 tons, fitted her with new engines, and went in her to Holland and up the Rhine to Coblenz. She was the first steamship to leave an English port. On his return he made material improvements in marine engines. He died, unmarried, the last of Watt's descendants, at Aston Hall, Warwickshire, on 2 June 1848 (Gent. Mag. 1848, ii. 207; Ward, Men of the Reign).[Williamson's Memorial of the Life and Lineage, &c., of James Watt, 1856; Smiles's Lives of Boulton and Watt, 1865; Muirhead's Origin and Progress of the Mechanical Inventions of James Watt, 1854; Muirhead's Life of Watt, 1858; E. A. Cowper in the Transactions of the Institution of Mechanical Engineers, 1883, on the ‘Inventions of James Watt and his Models preserved at Handsworth and at South Kensington;’ ‘Watt’ in the Encyclopædia Britannica, 6th ed. 1823, by James Watt, junr.; Muirhead's Correspondence of the late James Watt on his Discovery of the Theory of the Composition of Water, 1846; Robison's Mechanical Philosophy: letters and notes by James Watt on the History of the Steam Engine; Farey on the Steam Engine, 1827; Law Reports: points reserved in Boulton and Watt v. Bull, and in Boulton and Watt v. Hornblower and Maberley; Specification of Wasbrough's patent, 1779; Specification of Pickard's patent, 1780; Edinburgh Review, vol. lxxxvii., Jeffrey on Watt and the Composition of Water; Phil. Trans. 1783 and 1784, vol. lxxiv.; Lardner on the Steam Engine, 1828 and 1851; Arago's Éloge, translated by Muirhead, 1839; North British Review, 1847, vol. vi.; Brewster on Watt's Discovery of the Composition of Water; Transactions of the Institution of Civil Engineers, Walker's (President) Address, 1843; Brougham's Lives of Eminent Men of Letters and Science, 1845; Edinburgh Review, xiii. 320; Rees's Cyclopædia, about 1814, ‘Steam Engine,’ by Farey on Watt's information; Stuart's Descriptive History of the Steam Engine, 1831.]