818 Transactions of the American Institute. 



simply fastened ropes to the beam which lifted the valves when 

 required. Iron reds were afterwards substituted for ropes, and thus 

 the machine was made automatic. Before Watt took out patents for 

 his double-acting engine, and in fact during our Revolutionary war, 

 Oliver Evans, of Philadelphia, devised an entirely new steam-engine. 

 Many erroneous anecdotes have crept into the biographies of invent- 

 ors ; for example, that of Watt, which is accompanied by a picture of 

 him as a little boy looking intently at the lid of a teapot, which was 

 raised when the steam could not escape at the spout; yet Watt said he 

 never thought of the power of steam until he was a fall grown man. 

 So the Marquis of Worcester, who never made a steam-engine, is 

 represented as sitting by an old fashioned fire-place, watching the 

 motions of the cover of a boiling pot. The story of the origin of 

 the high pressure engine is more curious, and yet is not contradicted 

 by any other statement. The brother of Evans and other boys were 

 celebrating Independence day ; having no gunpowder, they procured 

 an old gun-barrel, stopped up the touch-hole, poured into the barrel a 

 little water and drove a plug in the end, and placed the barrel in the 

 fire of a blacksmith's forge. The plug was finally driven out with a 

 loud report, and with such force as to go through the wooden side of 

 the shop. From the account of that feat Evans first found out that 

 great force can be obtained from the direct action of steam. He set to 

 work to devise a plan for using this force. 



In the year 1779 he perfected his invention of the high-pressure 

 steam engine, and it came from his brain, like Minerva from that 

 of Jove, complete. Evans made the first locomotive, and the first 

 cylindrical boiler which contained a flue. For many years these 

 boilers were made of wooden staves and bound with iron hoops. This 

 invention is now called the Cornish boiler. Although the outside of 

 the boiler was made of wood, it contained a wrought-iron flue in 

 which a fire was made with wood. Some of these boilers have con- 

 tinued in use up to within a comparatively recent period. 



The next great improvement of the steam-engine, also made in this 

 country, was the application of the variable cut-off, first used on 

 marine engines by Sickles, and first applied successfully to stationary 

 engines by Corliss. With the cut-off', of which there are now many 

 ingenious varieties, the high pressure engine uses steam just in pro- 

 portion to the amount of work to be done. Thus the American engine 

 is literally and perfectly automatic in its action, and by means of its 

 own governor it controls itself with a light or heavy load more per- 

 fectly, and decides more correctly than any engineer could, the 



