INGENUITY AND LUXURY 



light enough so as to be carried to any part of a build- 

 ing, connected to the compressed-air tank by a rubber 

 cable. 



Every one who has been in the immediate vicinity 

 of a modern steel-frame building in the course of con- 

 struction is familiar with the sound, if not the mech- 

 anism, of the pneumatic hammer used for riveting. 

 It is utterly impossible to escape it. The shrill br-r-r-r-r 

 of the rapidly repeated strokes, striking against the 

 metal rivet at the rate of 1,500 to 3,500 blows a minute, 

 can hardly fail to attract attention. This pneumatic 

 hammer may be taken as a typical representative of 

 the class of percussion tools adapted to many other 

 purposes besides that of riveting. It is about three 

 inches in diameter and eighteen inches long, containing 

 a cylinder in which works a piston with a back and forth 

 action, driven by compressed air admitted and exhausted 

 by suitable openings. For convenience in holding 

 there is a handle at one end which is held by the oper- 

 ator, who presses the other end of the tool, which con- 

 tains the rivet-set, against the red-hot rivet. He then 

 presses the trigger-like throttle, admitting the com- 

 pressed air, and holds the rapidly striking hammer 

 in place until the riveting is completed a matter of 

 seconds only. 



As some counter-pressure is necessary for holding the 

 rivet in place, these hammers are frequently made with 

 a U-shaped end, particularly for special work in facto- 

 ries. But since these are not practical when working 

 in many places in steel-frame construction, the hammers 

 for this purpose do not have the U-shaped end, as a 



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