Part 10 (1/2)
The steam-pipe, _a b d d e_, leads the steam from the boiler to the cha_, leads from _h_ and _i_ to the condenser In the sketch, the upper steam and the lower exhaust valves, _b_ and _f_, are opened, and the steam-valve, _e_, and exhaust-valve, _c_, are closed, the piston being near the upper end of the cylinder and descending _l_ represents the plug-frae the lever, _s_, at either end of its throw, and turn the shaft, _u_, thus opening and closing _c_ and _e_ si-links, 13 and 14 A si-rod move the valves, _b_ and _f_, by means of the rods, 10 and 11, the ar the shaft, _t_, and thusthe arhts, carried on the ends of the arms, 4 and 15, retain the valves on their seats when closed by the action of the tappets When the piston nearly reaches the lower end of the cylinder, the tappet, 1, engages the ar the stea the exhaust-valve, _f_ At the sa the arm, _s_, doard, opens the steaer issues from the steaine-cylinder (not shown in the sketch); but it now enters the engine through the valve, _e_, forcing the piston upwards The exhaust is simultaneouslyfroh _c_ and the pipe, _g_, into the condenser
This kind of valve-gear was subsequently greatly ienious and efficient foreines of this class by the eccentric, and the various forear driven by it
[Illustration: FIG 33--Watt's Half-Trunk Engine, 1784]
The ”trunk-engine” was still another of the aline is described in his patent of 1784, as shown in the acco 33), in which _A_ is the cylinder, _B_ the piston, and _C_ its rod, encased in the half-trunk, _D_ The plug-rod, _G_,the catches, _E_ and _F_, as was usual with Watt's earlier engines
Watt's stea
34, in which _A_ is the stea evidently of the form just described It works a beam, _C C_, which in turn, by the rod, _M_, works the hammer-helve, _L J_, and the ha, and the block, _N_, the anvil
[Illustration: FIG 34--The Watt Hammer, 1784]
Watt found it iines at all times by measurement of the work itself, and endeavored to find a way of ascertaining the power produced, by ascertaining the pressure of steam within the cylinder This pressure was so variable, and subject to such rapid as well as extreme fluctuations, that he found it ie constructed for use on the boiler He was thus driven to invent a special instruine indicator” This consisted of a little stea piston, which e which was li, by means of which the piston was secured to the top of its cylinder The distance through which the piston rose was proportional to the pressure exerted upon it, and a pointer attached to its rod traversed a scale upon which the pressure per square inch could be read The lower end of the instruine by a s of the latter perine-cylinder to fill the indicator-cylinder, and the pressure of steam was always the same in both cylinders The indicator-pointer therefore traversed the pressure-scale, always exhibiting the pressure existing at the instant in the cylinder of the engine When the engine was at rest and steam off, the indicator-piston stood at the saine, and the pointer stood at 0 on the scale When steam entered, the piston rose and fell with the fluctuations of pressure; and when the exhaust-valve opened, discharging the stea a vacuum in the steam-cylinder, the pointer of the indicator dropped below 0, showing the degree of exhaustion Mr Southern, one of Watt's assistants, fitted the instru board, moved horizontally backward and forward by a cord or link-work connecting directly or indirectly with the engine-bea it a motion coincident with that of the piston This board carried a piece of paper, upon which a pencil attached to the indicator piston-rod drew a curve The vertical height of any point on this curve above the base-line measured the pressure in the cylinder at the moment when it was made, and the horizontal distance of the point froraine-piston The curve thus inscribed, called the ”indicator card,” or indicator diagrae in the pressure of steaine, not only enabled the ine to be deterineer, it was a perfectly legible stateine, and revealed aline which could not readily be detected by external exaineers' stethoscope,” opening the otherwise inaccessible parts of the steaineer even ives hians contained within the huineers' instrureatly iine had, by the construction of the iiven its distinctive forreat inventor subsequently did littlethe forms and proportions of its details As thus practically completed, it eine; and, as we have seen, the marked features of our latest practice--the use of the double cylinder for expansion, the cut-off valve-gear, and surface-condensation--had all been proposed, and to a liine has here ceased to be rapid, and the changes which followed the completion of the work of James Watt have been minor improvements, and rarely, if ever, real developments
Watt's mind lost none of its activity, however, forfurnace,” in which he led the gases produced on the introduction of fresh fuel over the already incandescent coal, and thus burned them completely He used two fires, which were coaled alternately Even when busiest, also, he found time to pursue more purely scientific studies With Boulton, he induced a nuham to join in the formation of a ”Lunar Society,” to meet monthly at the houses of its members, ”at the full of the moon” The time was thus fixed in order that those members who came fros, by land; but that at Biruished of them all Boulton, Watt, Drs S their occasional visitors were Herschel, Ss ”Philosophers'the period of s” that Cavendish and Priestley were experien, to determine the nature of their combustion Watt took much interest in the subject, and, when informed by Priestley that he and Cavendish had both noticed a deposit of ases, when contained in a cold vessel, and that the weight of this water was approxiases, he at once caen produced water, the latter being a chemical compound, of which the for, and the conclusions to which it had led him, to Boulton, in a letter written in December, 1782, and addressed a letter some time afterward to Priestley, which was to have been read before the Royal Society in April, 1783 The letter was not read, however, until a year later, and, threethe same announcement, had been laid before the Society Watt stated that both Cavendish and Lavoisier, to whom also the discovery is ascribed, received the idea froanic coloring- with their hydrogen, was uished French chemist, and the former i his father-in-law, Mr Macgregor, to make a trial of it
The copartnershi+p of Boulton & Watt terminated by limitation, and with the expiration of the patents under which they had been working, in the first year of the present century; and both partners, now old and feeble, withdrew froreement and to carry on the business under the same firm-style
Boulton, however, still interested himself in some branches of manufacture, especially in his mint, where he had coined many years and for several nations
Watt retired, a little later, to Heathfield, where he passed the remainder of his life in peaceful enjoyment of the society of his friends, in studies of all currentOne by one his old friends died--Black in 1799, Priestley, an exile to America, in 1803, and Robison a little later Boulton died, at the age of eighty-one, August 17, 1809, and even the loss of this nearest and dearest of his friends outside the faory, who died in 1804
Yet the great engineer and inventor was not depressed by the loneliness which was gradually co upon him He wrote: ”I know that all men must die, and I submit to the decrees of Nature, I hope, with due reverence to the Disposer of events;” and neglected no opportunity to secure amusement or instruction, and kept body and s of the club, uishedof his fondness for invention, and spentstatuary, which he had not perfected to his own satisfaction at the time of his death, ten years later This raph, which could be worked in any plane, and in which the -point followed the surface of the pattern, while the cutting-point, following its motion precisely, formed a fac-simile in the material operated upon
In the year 1800 he invented the water-ow Water-Works Company across the Clyde The joints were spherical and articulated, like those of the lobster's tail
His workshop, of which a sketch is hereafter given, as drawn by the artist Skelton, was in the garret of his house, and ell supplied with tools and all kinds of laboratory --desk in the corner Here he spent the greater part of his leisure ti his o to the table for them Even when very old, he occasionallyon his old friends and studying the latest engineering devices and inspecting public works, and was everywhere welcoineer, or as the kind and wise friend of earlier days
He died August 19, 1819, in the eighty-third year of his age, and was buried in Handsworth Church The sculptor Chantrey was erave, and the nation erected a statue of the great reatest of all the inventors of the steath than its subject justifies Whether we consider Watt as the inventor of the standard steaator of the physical principles upon which the invention is based, or as the builder and introducer of the reat sources of power in Nature are converted, adapted, and applied for the use and convenience of man,” he is fully entitled to preeminence His character as a ineer
Srapher, writes:[41]
[41] ”Life of Watt,” p 512
[Illustration: FIG 35--James Watt's Workshop (From Smiles's ”Lives of Boulton and Watt”)]
”Soarret at Heathfield in which Watt pursued the investigations of his later years The room had been carefully locked up since his death, and had only once been swept out Everything lay very much as he left it The piece of iron which he was last e, lay on the lathe The ashes of the last fire were in the grate; the last bit of coal was in the scuttle
The Dutch oven was in its place over the stove, and the frying-pan in which he cooked hison its accusto the pursuits which had been interrupted by death--busts, -machine--many medallion-moulds, a store of plaster-of-Paris, and a box of plaster casts from London, the contents of which do not see lead, his foot-rule, his glue-pot, his ha mirrors, an extemporized calasses laid about, indicate interrupted experilasses, cohts, and sundry boxes of hly prized In one place a overnor, in another of the parallel-motion, and in a little box, fitted ooden cylinders ures, is e suppose to be a -machine On the shelves are minerals and chemicals in pots and jars, on which the dust of nearly half a century has settled Thesince dried up; the putty has been turned to stone, and the paste to dust On one shelf we corapes On the floor, in a corner, near to where Watt sat and worked, is a hair-trunk--a touching -dead sorrow It contains all poor Gregory's school-books, his first attes of battles, his first school-exercises down to his college-theraht into this retired room, where the father's eye could rest upon them Near at hand is the sculpture- to the last Its wooden fra into dust, like the hands that one to rest, with all his griefs and cares, and his handiwork is fast cruht which he put into his inventions, still survives, and will probably continue to influence the destinies of his race for all time to come”
The visitor to Westminster Abbey will find neither monarch, nor warrior, nor statesman, nor poet, honored with a nobler epitaph than that which is inscribed on the pedestal of Chantrey's monument to Watt:
NOT TO PERPETUATE A NAME, WHICH MUST ENDURE WHILE THE PEACEFUL ARTS FLOURISH, BUT TO SHOW THAT MANKIND HAVE LEARNT TO HONOR THOSE WHO BEST DESERVE THEIR GRAtitUDE, THE KING, HIS MINISTERS, AND MANY OF THE nobLES AND COMMONERS OF THE REALM, RAISED THIS MONUMENT TO JAMES WATT, WHO, DIRECTING THE FORCE OF AN ORIGINAL GENIUS, EARLY EXERCISED IN PHILOSOPHIC RESEARCH, TO THE IMPROVEMENT OF THE STEAM-ENGINE, ENLARGED THE RESOURCES OF HIS COUNTRY, INCREASED THE POWER OF MAN, AND ROSE TO AN EMINENT PLACE AMONG THE MOST ILlustRIOUS FOLLOWERS OF SCIENCE AND THE REAL BENEFACTORS OF THE WORLD