PROVING BARRELS. . 419 



is laborious in the extreme, and quite uncertain, except in the 

 hands of very superior and skilful mechanics. 



The process of turning by a simple lathe is as follows : The 

 barrel beinsj fixed in the lathe, an inch or so of the surface, 

 both at the breech and muzzle end, is turned to the proper 

 diameter; the rest is then removed to a distance of four or five 

 inches from these points, and another inch or so of the surface 

 at either end is removed, and so on, having great care, however, 

 at each operation, to make the depth of the turning correspond 

 with the size and caliber of the barrel. This part of the 

 process being accomplished, the next step is to file away, by 

 means of an instrument termed a float, the projecting surfaces 

 of the barrel intervening between the parts cut out by the lathe ; 

 the barrels are now readv for breeching and the tests of the 

 proof-house. 



BRAZING AND BREECHING. 



The barrels for double guns are now filed away at the breech 

 and muzzle, to make them lie against each other snugly, bound 

 together, and then brazed with hard solder or brass for several 

 inches. This latter practice of brazing is highly censured by 

 Greener, who asserts that, in common barrels, their strength is 

 injured twelve and a half per cent,, and, in hammer-hardened 

 barrels, even to a much greater extent. His ideas on the sub- 

 ject are doubtless very correct, as the heating of the metal 

 afresh to a white heat, for the purpose of brazing, must of 

 necessity diminish a portion of that tenacity or strength which 

 it had already acquired by the process of hammer-hardening. 

 This being finished, the barrels are now tapped or turned out, 

 ready for the reception of the breeches, and are then sent to the 

 proof-house. 



PROVING BARRELS 



There is no department in the manufacture of a gun in which 

 there is more deception than that of the proving-house ; we do 

 not wish to be understood that frauds upon the public actually 

 take place under the eye, and with the full cognizance of the 



