BORING. 417 



facture of the barrel, and the more expensive is the getting of 

 it up. The rods for wire-twist barrels are extremely narrow, 

 only three-eighths of an inch or less in width, and the quantity 

 of spirals is consequently increased. 



After the hoops have been twisted round the rods, the spirals 

 are joined together by heating the unclosed cylinder to a welding 

 heat, and striking the end against the anvil, which springs them 

 together so forcibly that, with a little hammering, the whole 

 cylinder becomes welded as if formed of only one continuous 

 piece. After the spirals are joined, the barrel is hammered in 

 the grooves of the anvil to make it perfectly round. 



It requires two, three, or four spiral cylinders, according to 

 the length of the piece, to make one barrel; and great nicety and 

 dexterity are necessary to join them together, so that the barrel 

 may appear to have been made out of one rod only. In common 

 barrels, this union of the rods may be distinctly seen upon ex- 

 amination before they are stained, and indeed very often after 

 they come from the stainer's hands. 



The next process in the manufacture of barrels is what \k 

 termed hammer-hardening, which is accomplished by beating 

 the metal for a considerable time in the grooves of the anvil 

 with light hammers, for the purpose of closing the pores, in- 

 creasing the density and elasticity, and rendering the texture 

 more firm, flexible, and solid. This labor is not often bestowed 

 upon ordinary barrels, got up merely for the home or foreign 

 trade, but on ordered or show guns only. 



BORING. 



The barrels are now submitted to the boring mill for the pur- 

 pose of giving them their proper caliber. This end is accom- 

 plished with the assistance of steam. The barrel being properly 

 arranged on a frame, the boring-bit is introduced into the muz- 

 zle, and, by the application of the necessary power, is made to 

 traverse the whole extent of the barrel, a stream of water play- 

 ing upon the metal during the whole process, for the purpose of 

 keeping down the heat that is engendered by the severe friction 

 of the bit, and which, if allowed to increase to its full extent, 

 might injure the quality of the metal. 

 27 



