270 VARIETIES OF SHOT-GUNS, ETC. 



at four inches from the breech end as in other guns at that 

 part itself. This will be better understood by referring to 

 fig. 42, which shows the chamber opened ready for the 

 reception of the cartridge, and which will then give an idea 

 of the part where the real barrel begins, which is marked a 

 in the cut. There must be enough strength behind this to 

 resist the backward action of the explosion, but the metal 

 need not be left of full thickness for this purpose, as the area 

 upon which the force is exerted is only that of the diameter 

 of the bore. The strain is not entirely upon the bolt-hole b, 

 which keeps the breech-plug up against the barrel, for the 

 base of the lock-cylinder is wedged up, and transmits 

 the recoil to the stock. There is nothing very peculiar in 

 other respects in Mr. Needham's barrels, which are relieved 

 before in the usual manner, and also opened behind to an 

 extent which will allow of the ready insertion of the car- 

 tridge. By this arrangement it will at once be seen that 

 when the breech-plug c is in its place, the chamber for the 

 reception of the powder is similar to that of the French gun 

 already described, and that there is no conical chamber 

 like that in the breech of the percussion gun. In this respect, 

 therefore, the two guns are alike ; and if there is any virtue 

 in the Manton, Wilkinson, or other form of breech chamber, 

 neither can claim it, and both in this matter stand on the 

 same footing. But when the mode of closing the breech 

 comes to be examined, it will be seen that this is more com- 

 plete in Mr. Needham's than in the French gun in one 

 particular, while it is less so in another, the balance of advan- 

 tage and disadvantage being somewhat difficult to strike. 



The breech-plug (tig. 41 a) should be considered as quite 

 independent of the lock, though it also contains that impor- 

 tant part within it, and has a small hole in its face to allow 

 of the needle being driven through it into the cartridge. In 

 this hole is the element of weakness, for through it, however 

 well the needle fits, will be a small escape of gas, consequent 

 upon the explosion. Independently of this the plug con- 

 sists of two parts, each of which serves a double office firstly, 

 of closing the breech, and secondly, of acting on or contain- 

 ing the lock. In reference to the breech, this plug may be 

 described as consisting of two portions an anterior (a, fig. 



