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CHAPTER XIX.

STEAM TILT-HAMMER — PATENT OF 1784 PARALLEL MOTION LOCOMOTIVE STEAM-CARRIAGES - COUNTER THROTTLE-VALVE GOVERNOR - STEAM BAROMETER OR FLOAT -STEAM-GAUGE INDICATOR -MOST INVENTIVE PERIOD OF MR. WATT'S LIFE — DEATH OF HIS FATHER — PATENT OF 1785 - CONSUMPTION OF SMOKE.

A FAVOURITE employment of Mr. Watt in the workshops at Soho in the latter months of 1783 and earlier ones of 1784, was to teach his steam-engine, now become nearly as docile as it was powerful, to work a tilt-hammer for forging iron and making steel. So far back as 3 May, 1777, he had informed Mr. Boulton that “[John] Wilkinson is going to work “ in the forge way, and wants an engine to raise a stamp of " 15 cwt. thirty or forty times in a minute. I have set Webb " to work to try it with the little engine and a stamp-hammer " of 60 lbs. weight. Many of these battering rams will be “ wanted if they answer.” During his long absence, and constant occupation in Cornwall, this labour seems to have been intermitted; and we do not find it resumed in earnest till November, 1782. Then the rotative motion and mill "part answered to every expectation, but the hammer-frame " and anvil-block were not sufficiently secured, which, how

ever, I have given orders for doing. And as the engine has " a great overplus of power, I mean to increase the weight of “the hammer to about 1) cwt., and to cause it to make 250 or 300 strokes per minute, by diminishing the height it

rises to 9 or 10 inches. The present facts are, cylinder, 15 " inches diameter, and 4 feet stroke, 25 strokes per minute; " hammer makes 6 blows per stroke of the engine; fly under “5 cwt., and 7 feet diameter; hammer 120 lbs., and 18 inches

wide; it strikes a good blow, and forges iron very well. “ The camms were wood, and were cut all to pieces by the “anyil-block sinking. I have ordered steel ones to be made, mentioned when treating of the patent of 1781, viz. that “self

acting rotative engines, not derived from the rectilinear “ motion of a piston in a cylinder, instead of being more

simple in their construction, are more complex than those " derived from reciprocating motions, and more difficult in “ execution,” it seems unnecessary to enlarge on this article, which is fully described in the specification.*

* See the specification of this third and the relative drawings, engraved steam-engine patent, printed in vol. ii. in the same volume, Plates VIII., IX., of the Mechanical Inventions of X., XI., XII., XIII., XIV., XV., • James Watt,' 1854, pp. 55 to 87; XVI., XVII., XVIII., and XIX.

CHAPTER XIX.

STEAM TILT-HAMMER - PATENT OF 1784 PARALLEL MOTION LOCO

MOTIVE STEAM-CARRIAGES COUNTER — THROTTLE-VALVE - GOVERNOR - STEAM BAROMETER OR FLOAT — - STEAM-GAUGE - - INDICATOR - - MOST INVENTIVE PERIOD OF MR, WATT'S LIFE — DEATH OF HIS FATHER PATENT OF 1785 CONSUMPTION OF SMOKE.

A FAVOURITE employment of Mr. Watt in the workshops at Soho in the latter months of 1783 and earlier ones of 1784, was to teach his steam-engine, now become nearly as docile as it was powerful, to work a tilt-hammer for forging iron and making steel. So far back as 3 May, 1777, he had informed Mr. Boulton that “[John] Wilkinson is going to work " in the forge way, and wants an engine to raise a stamp of “ 15 cwt. thirty or forty times in a minute. I have set Webb “ to work to try it with the little engine and a stamp-hammer " of 60 lbs. weight. Many of these battering rams will be "wanted if they answer.” During his long absence, and constant occupation in Cornwall, this labour seems to have been intermitted; and we do not find it resumed in earnest till November, 1782. Then “ the rotative motion and mill "part answered to every expectation, but the hammer-frame " and anvil-block were not sufficiently secured, which, how"ever, I have given orders for doing. And as the engine has " a great overplus of power, I mean to increase the weight of " the hammer to about 1} cwt., and to cause it to make 250 or 300 strokes per minute, by diminishing the height it

rises to 9 or 10 inches. The present facts are, cylinder, 15 “ inches diameter, and 4 feet stroke, 25 strokes per minute ; “hammer makes 6 blows per stroke of the engine; fly under “ 5 cwt., and 7 feet diameter; hammer 120 lbs., and 18 inches wide; it strikes a good blow, and forges iron very well. “ The camms were wood, and were cut all to pieces by the " anvil-block sinking. I have ordered steel ones to be made,

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“ which I expect will stand it." * On the 30th of November he says,—“I saw the tilt go admirably from 16 to 24 strokes

per minute, and it could have gone much faster, but our “ men could not work the iron under it. Joseph said that yesterday they made it go 28 strokes per minute, which is “ much more than the engine should do by my calculations; so but in the midst of our glory, the hammer helve broke : it

appears to have been rotten. The steel camms answer very well, and the whole will answer better when made to have

less lift and more strokes, as it will then answer for a “common tilt for steel; at present the blow is so strong, that “ we dare not attempt to hack a piece of iron under 12 inch

square, otherwise it knocks it to pieces. By the help of “ some more weight on the outer end of the beam, it goes so “ regular that you cannot tell when the engine is going out “ or when coming in.” On the 12th of December,—“I went “ out to Soho yesterday forenoon, hoping the engine would “ be ready for trial, but it was not. In the evening they

wrought it 2 hours, 240 blows per minute, rise of hammer “ 8 inches." On the 13th,—“We have tried our little tilting“ forge hammer at Soho, with success. The following are

some of the particulars :-cylinder 15 inches diameter, 4 “ feet stroke, strokes per minute 20. The hammer-head, “ 120 lbs. weight, rises 8 inches, strikes 240 blows per minute. “ The machine goes quite regular, and can be managed as

easily as a water-mill. It requires a very small quantity “ of steam, not above half the contents of the cylinder per “ stroke. The power employed is not more than of what “ would be required to raise the quantity of water which 6 would enable a water-wheel to work the same hammer with “ the same velocity.” Next month, they were “ making an“ other to work a hammer of 700 lbs., which will soon be at “ work.” This was for Mr. John Wilkinson at Bradley, and, on the 27th of April, 1783, Mr. Watt writes, “ We have had a “ trial of our new forge-engine at Bradley; cylinder 42 inches “ diameter, 6 feet stroke. Makes from 15 to 50 (even 60

* To Mr. Boulton, 28 November, 1782.

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“strokes per minute) at pleasure, works a hammer of 7} cwt. “ raised 2 feet high, which makes 6 strokes per stroke of the

engine, and has struck 300 blows per minute; we are, how"ever, going to make it strike only 41 blows per stroke of " the engine, because we want the latter to go 20 strokes per

minute, and they want only 90 blows of the hammer in " that time; but will increase the weight of the hammer to "10 cwt. N.B. The engine is to work two hammers, but is “ capable of working four hammers, of 7 cwt. each.”

In a letter written on the previous day, he had said, with excusable pride, “I believe it is a thing never done before, " to make a hammer of that weight make 300 blows per “ minute; and, in fact, it is more a matter to brag of than “ for any other use, as the rate wanted is from 90 to 100 “ blows, being as quick as the workmen can manage the iron “ under it.”

This most valuable application of steam-power was, accordingly, reserved for insertion in yet another patent, which Mr. Watt took out on the 28th of April, 1784. The relative specification, enrolled on the 25th of August in that year, may probably be viewed as second in importance to none of those prepared by Mr. Watt subsequent to that of the Separate Condenser in 1769; as, besides many improvements now of minor consequence, such as steam-wheels, balancing of pumprods, communication of motion from the same engine to two separate primary axes, and apparatus for opening the regulating valves with rapidity, it contains various methods of converting a circular or angular motion into a perpendicular or rectilineal motion,-one of those methods being the wellknown and much-admired Parallel Motion ;-a method of working a tilt-hammer for forging iron, making steel, &c., by steam ;—and the application of the steam-engine to give motion to wheel carriages for carrying persons or goods.

Of the last-mentioned invention, and of its inventor's views of the subject of locomotion by steam, in general, we shall presently treat. Of the invention of the Parallel Motion,-a beautiful mechanical puzzle which different philosophers have attempted to explain in various ways, but which has uni

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