MITIEDEA.D'S MEMOIR AND CORILESPONDENCE OF ;IMES WATT. * VARIOUS lives of

James Watt have been published in various forms. The " doge " of Arago presented the scientific intellect of the great discoverer, with an acumen and a completeness that left little for future biographers. Lord Brougham's sketch was a rapid and vigorous narrative of the striking points in Watt's career and cha- racter. Other lives have appeared, in which the story is told with less breadth and force, but with more fulness of faets and 4reater sobriety if not accuracy. Mr. Muirhead's memoir, prefixed to the correspondence in the volumes before us, deals chiefly with Watt as a natural philosopher, inventor, and man of buainess. In fact, Watt as exhibited in his correspondence and business is the main characteristic of the publication; the memoir being chiefly founded on letters, though the biographer occasionally mentions some traits of private life, mixed with passing notices of Watt's friends. The letters themselves follow the memoir; commencing in 1765, when the inventor began his investigations on the steam-engine, and con- tinuing till towards the time of his death in 1819. The life and letters are contained in two volumes. The third volume consists of the various patents that Watt took out, and their specifications, with illustrative drawings ; some curious information on the history of the steam-engine before Watt's discovery ; and a variety of matter connected with the two great trials at the instance of Boulton and Watt for the infringement of their patent. The prime literary feature of the work is the correspondence ; in the selection of extracts from which Mr. Muirhead seems to have exercised discrimination. When the length of time over which the correspondence extends is borne in mind, the extracts cannot be considered unduly numerous ; and this is creditable to the editor. Gaps are met with occasionally, and that too in the earlier and more interesting part ; but these probably are unavoidable. The letters may have been lost, or some other mode of communica- tion adopted. Upon Mr. Muirhead's principle of proceeding—that of dealing with the philosophical and business career of Watt, the work is complete enough. In three ample octavo volumes the reader is entitled to expect a fuller biography. It may be tame that the particulars of Watt's childhood, school days, and family, can be found in Arago and other writers ; but they were only special notices or sketches. A work of this extent should be as complete as it could be made ; and that it cannot be without as full an account as can be given of the studies of Watt, and the manner in which he pursued them, as well as of his early bias and training. Indications of his studies and industry, indeed, often appear; but the reader wants a more continuous and complete narrative. It is only incidentally that he finds out that Watt was born in 1736 and at Greenock. He learns scarcely anything of Watt's family, though it was respectable. Indeed, his family connexions, and the friends they were a means of introducing him to, very materially contributed to his success. Neither his bodily health nor hiss;nental audacity would have enabled Watt to force himself upon the world. Happily, he met with judicious, zealous, and high-principled friends, who encouraged him to persevere when he was desponding, and aided him in a practical way.

The work possesses great interest to the student of me- chanics, the natural philosopher, and the inquirer into mind and character. We trace, though not so completely as might be desired, the struggles and baking failures through which a great conception is finally realized ; as well as the periods of gloom and depression by which bad health, constitutional despondency, and temporary disappointment, darken the spirits of the discoverer. Many subjects of natural philosophy are noticed in the corre- spondence, especially in relation to steam : and very curious it is to observe how the scientific minds of the age were employed upon it. Before Watt had begun his experiments, Professor Robison, then a student at Glasgow, conceived the notion of moving land-carriages by steam. When Watt had explained his ideas to his confidential friends, before their practicability was publicly established, they instantly seized upon steam as the subject of speculation. Indeed, their ideas were pushed into more than all the channels in which the invention has since been employed. Several thought of steam-carriages for common roads. Dr. Small of Birmingham, a fast friend of Watt, had an idea of posting by steam instead of horses. He also thought of steam-boats for canals, to be moved, it would appear, by paddle-oars. Watt answered his letter, suggesting a spiral oar, with a sketch of what he meant ; which is, as Mr. Muirhead remarks, undoubtedly a screw pro- peller. Watt himself appears to have turned his attention to steam-carriages. In 1813, Edgeworth, writing to him, . speaks of the railway in express terms. "I have always thought that steam would become the universal lord, and that we should in time scorn post-horses. An iron railroad would be a cheaper thing than a road on the common construction." Iron railways were already in existence for easing horse-draught, though they were premature and failed; we think the Wandsworth and Merstham tram-way was as old as 1807. The conception of a plan, however, is of little value till it is realized in the form which its nature requires. He only is entitled to the fame and profit of an inventor who renders an idea practically available; all the others are mere saggesters. man may conceive a poem or a picture, but he alone is the poet or painter who presents the world with the work. The impression left by the book is the importance of labour. From the time when, after an irregular education in mechanical

• The Origin and Progress of the Mechanical Inventions of James Watt Mtn-

trated by his Correspondence with his Friends and the Specifications of his Patents. By lames Patrick Muirhead, Esq., M.A. In three volumes. Published by Murray.

business as well as other things, Watt went to London at eighteen to learn mathematical-instrument-making with a view to a future

livelihood, he was ever employed. This in the book is rather visible incidentally and by results than by actual telling: but whatever excited the attention of the youthful philosopher he mastered. When the steam-engine was brought before him, he acquired its history as well as its principles, so far as was then known. He studied optics, and all the sciences connected with natural philo- sophy, apparently without any instruction beyond what he gathered from books. He made himself one of the first civil engineers ; building bridges, constructing canals with locks and tunnels; he even a made a survey for what is now the Caledonian Canal. He acquired languages through the same zeal of mastering a thing completely. He learned the German language in order to peruse Leopold's " Theatrum Machinarum," says his old friend Dr. Robi- son; and "Italian for similar reasons." Yet he seems to have been always at leisure for conversation, or even scientific gossip with his friends ; and it should be remembered that in the early part of his career his living depended upon his handicraft. The gains from this at the outset he humbly fixed at forty shillings a week. However, money in Glasgow a hundred years ago com- manded much more than it does now.

The anxious difficulties of an inventor are fully impressed on the reader by the correspondence, even when the invention was only an improvement, and the principles as well as the method of working them distinctly present to the inventor's mind, while that inventor was himself capable of mechanically realizing his conceptions. The primary action of the steam-engine, as Watt found it, is pretty much as it is now. The piston rose and descended through a cylinder, but the ascent only was effected by steam, the descent by atmospheric pressure. The action were all produced in the cylinder itself ; a cock turning on the steam. When the piston had been forced up, another cock turning cold water into the cylinder condensed the steam and produced a vacuum, when the pressure of the atmosphere caused the piston to descend. By this process, great waste of steam and therefore of fuel took place. Watt's invention really consisted in condensing the steam in a separate vessel called the condenser, so that the cylinder was not perpetually chilled and steam wasted ; and by causing the piston to descend by steam-power instead of at- mospheric pressure. Improvements of various kinds accompanied or followed this new engine ; but they were of a mechanical kind. The separate condenser was the thing. Watt himself affirms that the actual principle was as clearly present to his mind in 1765 as when it was finally realized. It was not, however, till 1769 that he took out his patent: the difficulties as re- gards practical success were then so great, or rather perhaps fail- ures were so frequent, that Boulton did not engage in the specu- lation till 1774-'5, and only on condition of an act being pro- cured to extend the privilege of the patent for twenty-five years longer ; which was obtained, through Watt's interest, in spite of strong opposition. Even then at first it did not pay, according to Watt ; but he seems to have been inclined to'croaking. Mechanical difficulties still intervened. In fact, but for the large resources and business enterprise of Boulton, the improved steam-engine might have very slowly displaced the old liewcomen's. The facts on which these conclusions are founded are scattered and minute ; they are often of a technical kind, and not well adapted to general apprehension. We will take a few of the most remarkable. 'Here is a passage written in the autumn after Watt had taken out his patent, and had just recovered from a tooth- ache. It is a true illustration of his own remark on another simi- lar occasion, that "great mischief often arises from small causes."

"Since that left me, I have been in better health than you could expect a valetudinary projector to be in, whose anxiety for his approaching doom keeps him from his night's sleep, and whose fears at least equal his hopes.

"I have no doubt but you would readily have excused this preamble, and would be glad to know somewhat of the health of the engine, as well as of the projector. Well, then, the trial has not been decisive; but I am still allowed to flatter myself with hopes. You shall judge. The adjusting and fitting all the parts together took longer time than we thought a; but, after much close labour, we got it brought to a trial about a fortnight ago. After the air was pumped out, the piston of the cylinder descended about two feet, and stopped there, being willing to come no further. Steam was admitted, and it ascended; on a second trial, it came down only a few inches. From some circumstances, I thought the bucket of the pump was in fault ; the water being let off and the bucket drawn, (which was not easily done,) the leather was found to be what we eallilyped, or turned inside out. On examining the piston of the cylinder, the pasteboard used for leather there, was found torn. It was conjectured that the jack- head hole might not be in the centre of the cylinder ; that was en- deavoured to be rectified, and three-ply of pasteboard was put on the piston instead of one. A double leather was put on the bucket, and the two were pinned together. We again set to work. After the air was pumped out, the piston descended briskly for a few strokes but grew gradually slower as the water rose in the pump. When the water came to the pump-head, the piston always waited some time after the valve was open to condensation before it descended. On suffering the strength of steam to increase, the piston descended more briskly, but I thought hardly in proportion to the in- creased pressure on it. The bucket of the pump made a groaning noise, by which I thought the friction in it might be more than usual, it having been rusty a little when put up. After some strokes the piston failed, and the oil came through the condenser. The piston being drawn, cork was put on in the same manner as the pasteboard ; the oil-pump was examined, and the passage through which it should discharge its oil found too small. This we could not remedy at Kinneil. On putting in the cork piston, in descending it did not apply itself to the cylinder at one place of one aide ; on examina- tion, the cylinder was oval in that place, either from some inaccuracy in the making or from some injury received in setting it up. This also we could not immediately remedy."

- Watt himself had not sufficient means to get beyond a modeL He was first assisted by Dr. Roebuck, who originated the Carron Iron Works. The Doctor, however, became embarrassed, and this was one source of delay in arranging with Boulton. Difficulties such as we have just quoted, narrow means, ill health, and, more than all perhaps, a melancholy temperament, induced him some- times to think of throwing up the thing altogether. This is from a letter to Dr. Small, in December 1773.

"I long much to see you,—to hear your nonsenses and to communicate my own ; but so many things are in the way, and I am so poor, that I know not when it can be.

"I am heart-sick of this country : I am indolent to excess, and, what alarms me most, I grow the longer the stupider. My memory fails me so as often totally to forget occurrences of no very ancient dates. I see myself condemned to a life of business : nothing can be more disagreeable to me I tremble when I hear the name of a man I have any transactions to wale with.

"The engineering business is not a vigorous plant here; we are in general very poorly paid. This last year my whole gains do not exceed 2001., though some people have paid me very genteelly. There are also many disagreeable circumstances I cannot write : in short, I must, as far as I see, change my abode. There are two things which occur to me, either to try England, or endeavour to get some lucrative place abroad : but I doubt my interest for the latter. What I am fittest for is a surveying engineer."

At a later date, when the arrangement with Boulton was draw- ing to a close, he had an offer to go to Russia, but seems to have been deterred by the ill-treatment and non-payment of some other person. The report alarmed his friends, and Darwin writes to him.

".Dr. Darwin to Mr. Watt.

"Lichfield, March 29, 1775.

"Lord, how frightened I was when I heard a Russian bear had laid hold of you with his great paw, and was dragging you to Russia! Pray don't go if you can help it. Russia is like the den of Cacus ; you see the footsteps of many beasts going thither, but of few returning. I hope your fire-engines will keep you here."

Even after Boulton's resources were brought to bear on the executive part, there was an occasional hitch.

"Mr. Boulton to Mr. Watt.

"Soho, [May 1775.]

"The engine goes marvellously bad. It made eight strokes per minute; but upon Joseph's endeavouring to mend it it stood still. Nor do I at pre- sent see sufficient cause for its dullness. I have a few 'minutes ago had the top taken out, and find that I can pump down the piston ; and although I can hear the air pass by it into the cylinder, yet the error is not sufficient to account for its bad going. The piston is now taken out, and although the cylinder is not perfect yet there doth not appear any very gross error. The outside of the piston is hat, filled up with paper chewed. It is nine inches thick at least, which I fear makes much friction. I have ordered a bottle of oil to be put into the papier-mache, which will drain through the hat and lubricate the sides. It is certain, by another experiment I made, that much steam escapes, as the water which passed through the condenser continued to be hot.'

In about a year matters began to mend.

"Mr. button to Mr. Watt.

"Soho, July 25, 1776.

"I have an application for an engine from a distiller at Bristol, to raise 15,000 ale gallons per hour 60 feet high ; I have another for a coal-mine in Wales, another for a Mr. Langdale of Holborn, a distiller, and another for Mr. Liptrap at Mile End, a distiller. The wheel-engine is ready for trial, except the steam-pipe - the boiler is set, and many wheels will be wanted so soon as they are read/for sale. I did not sleep last night, my mind being absorbed in steam ; and thus I reasoned in my waking dreams."

A little longer and there was the effulgence of a bright dawn. "Mr. Boulton to Mr. Watt.

" [1776.] "If we had a hundred wheels ready-made, and a hundred small engines like Bow engine, and twenty large ones executed, we could readily dispose of them. Therefore let us make hay whilst the sun shines, and gather our barns full before the dark cloud of age lowers upon us, and before any more Tubal-Caine, or Watts, or Dr. Fausts, or Gainsboroughs, arise, with serpents like Moses's, that devour all others.

"Mr. Boulton to Mr. Watt.

" Soho, November 31, 1766.

"We have a positive order for an engine for Ting-Tang mine; and from what I heard this day from Mr. Glover, we may soon expect other orders from Cornwall. Our plot begins to thicken apace; and if Mr. Wilkinson don't bustle a little as well as ourselves, we shall not gather our harvest be- fore sunset I perceive we shall be hard pushed in engine work, but I have no fears of being distanced when once the exact course or best track is determined upon."