AMERICAN INDUSTRIES SINCE COLUMBUS. 337 



into action. This consisted of a heavy lever, X, which had its 

 fulcruni on the hammer-block, F F. The shorter arm of this 

 lever rested in contact with a vertical bar connected with the 

 valve-gear, P, in snch a way that at whatever point of its length 

 the bar chanced to receive a side pressure from the short arm of 

 the lever, X, it caused the admission of steam to the lower end of 

 the cylinder, D, thus causing the " hammer-block " to make its 

 upward stroke. This occurred automatically the instant after 

 the delivery of the blow ; the inertia of the weighted end of the 

 lever not being overcome, it moved downward after the " ham- 

 mer-block" came to rest, and forced its short arm against the 

 vertical bar in the manner described. Such, in brief, were the 

 construction and operation of the first steam hammer built in 

 America, and placed by its builders in the smith's shop of their 

 Southwark Foundry, at Philadelphia, where (Mr. J. Vaughn Mer- 

 rick writes me) it was " continuously employed till after the sale 

 of the works in 1871." 



The original invention of Nasmyth has undergone many 

 changes, and since the expiration of his patents a multitude 

 of modifications having for their object the improvement of 

 its action or its adaptation to some particular variety of work 

 have been brought forward ; but they all involve the funda- 

 mental ideas of lifting a vertically guided heavy mass, or ham- 

 mer-block, by the direct action of steam upon a piston with 

 which it is connected, and letting it fall at pleasure upon the 

 work in hand by cutting off the supply of steam and releas- 

 ing that already beneath the piston ; and this combination of 

 ideas and methods originated with James Nasmyth, who, by 

 his invention, augmented the strength of the arm of Vulcan 

 and conferred new powers and possibilities upon the skill 

 of man. 



The appearance of a modern forge and all its Vulcanian ac- 

 tivities is well represented by Fig. 30, which to an experienced 

 eye presents what may be called a scene of well-regulated con- 

 fusion, in which, amid smoke and flame, coal and iron, the hiss- 

 ing of steam, beating of sledges, ringing of anvils, and the 

 scorching glare of white-hot metal, the stalwart, half-naked sons 

 of Vulcan strain and sweat at their appointed tasks, while the 

 solid earth for miles around quakes under the ponderous blows 

 of the Cyclopean hammer * that 



. . . upheaves its mighty arm 

 While on the anvil turns the glowing mass 



* This is no exaggeration, as it has been authoritatively stated that the blows of the 

 steam hammers in Woolwich Arsenal have been felt at Greenwich Observatory, about two 

 miles distant. 



