orary member thereof. It was afterwards exhibited through the whole of the United States of America, with great eclat.

South Carolina, Mr. Watson was elected an hon- | tary public school of Greenock, but the delicacy of his health interfered with his regular attendance on the classes, and for the greater part of his time he was confined to his chamber, where he devoted himself to unassisted study. He early displayed a partiality for mechanics, and when only six years of age he was observed at work with a piece of chalk upon the floor of a room drawing a geometrical problem. While still a mere boy, his attention began to be attracted to the great power of steam, as the following interesting anecdote will show:-His annt, Mrs. Muirhead, sitting with him one evening at the tea-table, said,

Sir John Watson Gordon, the distinguished portrait painter, who was elected president of the Royal Scottish Academy, on the death of Sir William Allan, in 1850, is the nephew of the subject of this memoir, who was a third cousin of Sir Walter Scott.

Among the paintings of Mr. Watson while president of the Scottish Academy. were:-Portrait of Sir Charles Kerr; The Hermit; James Hogarth; Colonel M'Donald, 91st regiment, and his Lady;"James, I never saw such an idle boy! Take a Forrest Alexander, painted for the Commercial Bank of Scotland; Jewish Doctor; Rev. Bishop Patterson; Old Soldier; Female Ornithologist; Sir Peter Murray, Threipland; Narrative interrupted, with Portraits of Gentlemen.

book, and employ yourself usefully; for the last half hour you have not spoken a word, but taken off the lid of that kettle and put it on again, holding now a cup and now a silver spoon over the steam, watching how it rises from the spout, and

WATT, JAMES, a celebrated natural philoso-catching and counting the drops of water." It pher and civil engineer, the great improver of the steam-engine, was born at Greenock, January 19, 1736.

His great-grandfather, a farmer of Aberdeenshire, was killed in one of Montrose's battles, when his property, being forfeited, was lost to the family. The son of this man, Thomas Watt, established himself in Greenock as a teacher of mathematics and the elements of navigation, and was baron bailie of the burgh of barony of Crawford's Dyke. He had two sons, the elder, John, a teacher of mathematics and surveyor in Glasgow, died in 1737, at the age of fifty, leaving a Survey of the River Clyde, from Glasgow to the Point of Toward,' which was published by his brother several years afterwards. The younger son, James, the father of the celebrated engineer, was a builder and merchant in Greenock, of which town he was for a quarter of a century councillor, treasurer, and one of the magistrates. He died at the age of 84, in 1782.

James Watt, the subject of this notice, was the elder and only surviving child of the latter, his brother, John Watt, a youth of promising abilities, being lost at sea soon after he came of age. He received his first instructions in reading from his mother, whose name was Agnes Muirhead, whilst his father taught him writing and arithmetic. He was afterwards placed at the elemen

appears that when thus reproved, his active mind was engaged in investigating the condensation by steam. We are told that he prosecuted almost every branch of science with equal success, and especially took so much interest in reading books on medicine and surgery, that he was one day detected conveying into his room the head of a child which had died of some obscure disease, that he might take occasion to dissect it.

After passing a year with some Glasgow relatives, in 1755, while only eighteen years old, a desire for improvement in mechanical art induced him to go to London, where he placed himself under the tuition of Mr. John Morgan, mathematical and nautical instrument maker, in Finch Lane, Cornhill. To that gentleman an apprenticeship fee of twenty guineas was paid with him. Ten hours a-day was given up to a trying sedentary employment, which involved much exertion of thought as well as much weariness to the frame. He also worked over hours to win a little money for himself, and made the sum of eight shillings a-week suffice for his nourishment. At the end of a year ill health compelled him to return to Greenock. He now pursued his studies and occupations without more instruction, and in 1757 settled in Glasgow as a maker of mathematical instruments. Meeting with opposition from some

of natural philosophy, to put in order a working model of a steam-engine upon Newcomen's construction, which had never worked well. In this machine, then first made known to Watt, the con

of the corporations, on account of his supposed in- | of the wind, and which showed, too, no deficiency fringement of their privileges, the professors of in its powers of harmony. the university interfered, and attached him to Having directed much of his attention to the their establishment. He had been employed to subject of the elasticity of steam, and its conserepair some astronomical instruments which had quent availability as a motive power, about 1761 been bequeathed to the university by a Jamaica or 1762 Watt tried some experiments on Papin's proprietor, and had suffered some injury by the digester,-the contrivance of an ingenious French voyage. This commission earned for him more emigré of that name, made in London to realize than the £5 which, as the records bear witness, in practice his discovery of its property of prohe received for his work. Before he had reached ducing a vacuum in space by means of refrigerahis twenty-first year he was allowed to occupy a tion, as a counterpoise and auxiliary to its elastismall workshop for carrying on his business with- | city, in obtaining an alternate or oscillatory moin the college precincts, with the title of "mathe- tion,-and he had worked with strong steam a small matical instrument maker to the university." He model of his own construction, but the imperfechad also an apartment within the college, where tions inherent to its application in the crude mohe lived. His principal protectors on the occasion del of the Huguenot doctor prevented him at the were Adam Smith, author of The Wealth of time from proceeding with it farther. In the winNations; Dr. Black, the celebrated discoverer of ter of 1763-4 he was employed by Professor Anlatent heat; Robert Simson, the eminent mathe-derson, who had succeeded Dr. Dick in the chair matician; and Dr. Dick, professor of natural philosophy. These great men thought then that they were only delivering a zealous and able workman from the overbearing of the corporations, but soon after recognising in him a first-structor,-a hardware dealer at Dartmouth, whose rate man, they bestowed on him their warmest friendship. Before the close of his residence in the university, which lasted six years, his workshop became a sort of academy, whither students, professors, and eminent men of Glasgow resorted, to discuss difficult questions of art, science, and literature. "When any difficulty arrested us in the university," says Robison, one of the most illustrious editors of the British Cyclopedia, in an unpublished paper quoted by Arago, "we used to run to our workman. When once excited, any subject became for him a text for serious study and discoveries. He never let go his hold, until he had entirely cleared up the proposed question.gine, the vacuum was at first produced by exterOne day the desired solution seemed to require that Leopold's work on machines should be read; Watt immediately learned German. On another occasion, and for a similar reason, he rendered himself master of the Italian language." Although totally insensible to the charms of music, and not able to distinguish one note from another, he constructed an organ, which exhibited essential imimprovements in the mechanical details, in the regulators, and in the method of measuring the force

name it bore,-following Papin in the use of the vacuum-producing, in conjunction with the expansive, qualities of steam, had,—by separating the digester of the latter, which was boiler, cylinder, and condenser in one, into two vessels; a boiler or caldron, and a cylinder; the former for generating the steam, and the latter, receiving it from the caldron, for exciting alternate motion, although of a slow kind, first by its expansion, and next by its condensation,-produced a real and useful motive power, and opened the way to further and far more important improvements on the part of the subject of our memoir. In Newcomen's en

nal refrigeration. A second and larger cylinder enveloped the working one, and into the circular space between them an ample quantity of cold water was poured, the chill of which gradually penetrated through all the thickness of the metal, and at least reached the steam itself. The tardiness with which steam would cool and lose its elasticity by means of such a process was a serious impediment to its general usefulness. But accident fortunately soon indicated a very simple

way of obviating it. The closely fitted but move- | dimensions; the quantity of cold water that must able circular plate called a piston, which travels be injected into the cylinder to give a certain force up and down the inner circumference of the cylin- to the piston's descending oscillation; and finally der with each expansion and contraction of the the elasticity of steam at various temperatures. steam below, was at the beginning of the eighteenth century, when the art of casting metallic cylinders was in its infancy, covered with water on its upper surface, intended to fill up the vacancies between its circumference and the surface of the cylinder. One day the piston leaked, and, to the great surprise of the workmen, the engine began to oscillate much faster than usual. It was discovered that the drops of cold water that fell into the cylinder, by passing through the steam, annihilated it rapidly. This incident led to the abandonment of exterior refrigeration, and means were taken to shed a shower of cold water throughout the capacity of the cylinder at the instant of the piston's descent. The alternate up and down motion now acquired all the desired swiftness. To open and close the taps for the alternate letting on and shutting off of the steam and cold water through apertures into the cylinder required the uninterrupted attention of the person whose duty this was. The observant attention of a play-loving boy, by name Humphrey Potter, by connecting these taps with cords to the beam which Newcomen attached to his piston rod, so as to be moved when it, in ascending or descending oscillation, reached positions at the times and in the directions required for such openings and shuttings, enabled him to join his companions in play, and for the first time the engine worked by itself.

The little model of Newcomen's engine in the hands of a workman like Watt had soon the defects of its construction removed; and from that time it was made to work yearly under the eye of the delighted students. A man of common mind would have rested satisfied with this success. Watt, on the contrary, saw cause in it for deep study. His researches were successively directed to all the points that appeared likely to clear up the theory of the machine. He ascertained the proportion in which water dilates in passing from a state of fluidity into that of vapour, the quantity and weight of steam expended at each oscillation by one of Newcomen's engines of known

Here was enough to occupy the life of a laborious physicist, yet Watt found means to conduct all these numerous and difficult researches to a good termination without the work of the shop suffering thereby. The properties of steam being considered, it will readily occur to the reader that two conditions irreconcilable with each other are required for the economic working of Newcomen's engine. When the piston descends, the cylinder requires to be cold, otherwise it meets steam more or less elastic retarding the operation of its descent by pressure of the external atmosphere. Again, when into a cylinder so cooled there flows steam at the high temperature of 212 deg., that steam has a portion of its heat abstracted by becoming partially fluid, and until the cylinder regains a temperature of boiling water, its elasticity will be greatly attenuated. Hence slowness of motion, for the counterpoise will not raise the piston until there is sufficient spring in the cylinder to counterbalance the action of the atmosphere. In consequence of this, the Glasgow model at each oscillation expended a volume of steam several times larger than that of the cylinder. Could the successive heatings and coolings, the inconveniences of which have just been described, be avoided, the expenditure of steam, or, in other words, of fuel, and consequently the pecuniary cost of the working of the machine, would be several times less. In the most simple manner Watt solved this apparently insolvable problem. It sufficed for him to add to the former arrangement of the engine a vessel totally distinct from the cylinder, and communicating with it only by a small tube furnished with a tap. This vessel, now known as the condenser, is Watt's principal invention. A discovery which has revolutionized the mechanics and politics of the globe deserves to have its action explained.

If there be free communication between a cylinder filled with steam and another vessel which contains neither steam nor air, the steam from the cylinder will pass rapidly into the empty vessel, and the movement will continue until the elasti

city becomes equal in both. If, by an abundant | centre by a hole furnished with greased tow stuffed and constant injection of water, the whole capa- | hard in, through which, however, the rod of the city and sides of this other vessel be kept con- piston has free motion, yet not allowing passage || stantly cold, then the steam will condense as soon to air or steam. The piston thus divides the caas it enters it; all the steam that formerly filled pacity of the cylinder into two distinct and wellthe cylinder will be gradually annihilated; the closed areas. When it has to descend, the steam cylinder will thus be cleared of steam without its from the caldron reaches freely the upper area sides being in the least cooled, and the fresh sup- through a tube conveniently placed, and pushes it ply of steam with which it will require to be filled, from top to bottom as the atmosphere had done will not lose any of its elasticity. Now the con- in the engine of Newcomen. There is no obstacle denser attracts to itself all the steam contained in to this motion, because while it is going on, the the cylinder, partly because it contains some cold base area of the cylinder only is in communication water, and partly because it contains no elastic with the condenser, wherein all the steam from fluids, but as soon as some steam has been con- that lower area reassumes its fluid state. As soon densed, these two conditions on which success as the piston has quite reached the bottom, the depended, have disappeared; the condensing wa- mere turning of a tap brings the two areas of the ter has become hot by absorbing the latent caloric cylinder, above and below the piston, into comof the steam, and a considerable portion of steam has munication with each other, so that both shall be been generated at the expense of that hot water. filled with steam of the same degree of elasticity, The cold water contained, besides, some atmo- and the piston being thus equally acted upon upspheric air, which must have been disengaged ward and downward, ascends, as in Newcomen's during its heating. If this hot water was not atmospheric engine, again to the top of the cylincarried away after each operation, together with der, merely by the action of a slight counterpoise. the steam and air contained in the condenser, in the long-run no effect would be produced. Watt, however, attained this treble purpose by the aid of a common pump, called an air-pump, the piston of which carries a rod suitably attached to the beam worked by the engine. The power required to keep the air-pump in motion diminishes so far that of the engine; but this is a very small portion indeed of the loss which under the previous arrangement was occasioned by the steam being condensed on the refrigerated surface of the body of the cylinder.

Another invention of Watt deserves notice, the advantages of which are easy to perceive. In Newcomen's engine, when the piston descended, it was by the weight of the atmosphere. Being much cooler than the metal cylinder, which was open at the top, in proportion as it expanded over the surface of its sides, it cooled them likewise; a cooling which was not compensated during the ascent of the piston except at the expense of a certain quantity of steam. This atmospheric action is eliminated in the engine of Watt by the following arrangement:-The top of the cylinder is closed by a metal cover, only pierced in the

Pursuing his researches on the means of economising steam, Watt further reduced the result of the refrigeration of the external surface of the cylinder almost to nothing. He surrounded the metal cylinder with a wooden casing of large diameter, called a jacket, promoting the uniform warmth of the enclosed cylinder, by filling the intermediate annular space with steam.

Such was Watt's engine as at the date when he took out his first patent in 1769-a modified, a vastly improved and incomparably more economical machine than Newcomen's, yet still, like it, having power only during the descending oscillation of the piston. By the facility of its working properties, capable perhaps, in skilful hands, of other uses, but only as yet, like it, a pump-a mere pump available for drainage, and rendered remunerative to him, by the payment on the part of the proprietors of mines who employed it, of a duty of the value of one-third of the coal saved by each of their engines. This duty established the commercial importance of the invention, even at this stage, by the fact, that the proprietors of one mine, the Chasewater, gladly compounded for it, by an annual payment for the work of three