160 THE SHOOTER'S GUIDE. 



barrel by a narrow base, from which it spreads out as 

 the head of a nail does from its shank; and, when se- 

 parated, leaves a pit or hollow in the metal. 



The crack and flaw are to be regarded as much 

 more dangerous than the chink ; as the efforts of the 

 powder are exerted upon the circumference, and not 

 upon the length, of the barrel. The flaw is much 

 more frequent than the crack : but the latter will fre- 

 quently occur, where the iron is of an inferior qua- 

 lity. All these defects, however, when only external 

 and superficial, are of no material consequence ex- 

 cept in point of neatness ; but when situated within 

 the barrel, they become a very serious and even dan- 

 gerous disadvantage, by affording a lodgment to 

 moisture and filth that corrode the iron, and thus con- 

 tinually enlarge the excavation till the barrel bursts. 



A common gun-barrel is formed in the following 

 manner : The workmen begin by heating and ham- 

 mering out a bar of iron into the form of a flat ruler, 

 thinner at the end intended for the muzzle, and 

 thicker at that for the breach; the length, breadth, 

 and thickness of the whole plate being regulated by 

 the intended length, diameter, and weight of the 

 barrel. This oblong plate of iron is then, by repeat- 

 ed heating and hammering, turned round a cylindri- 

 cal rod of tempered iron, called a mandril, whose dia- 

 meter is considerably less than the .intended bore of 

 the barrel. The edges of the plate are made to over- 

 lap each other about half an inch, and are welded to- 

 gether by heating the tube in lengths of two or three 



