MR. NEEDHAM'S NEEDLE GUN. 271 



41), which is projected into the barrel, and a posterior part, 

 which forces it forward as the screw is turned by the lever. 

 The part a terminates in a short cone which fits accurately 

 into the barrel, and with the aid of the wad at the base of 

 the cartridge closely fills the aperture and prevents the 

 escape of gas between the two circumferences. But the 

 centre of this, where it is pierced by the needle, as shown in 

 fig. 40, is not so completely free from escape, and to prevent 

 the gas from passing backwards into the lock, a hole is drilled 

 as there indicated. These two divisions are each tapped, the 

 anterior one being constructed with a female screw, and the 

 posterior showing a male screw of a strong formation (fig. 

 41 b). The effect of this is so obvious as scarcely to require 

 the explanation that, when one is fixed as it is by the bolt 

 (fig. 42 b), and the other is turned by the lever, the total 

 length is increased or diminished as the case may be. The 

 pitch of the screw is so slight that no force which can be 

 applied by the explosion will drive the plug back ; and its 

 lever, when closed, being also held in its place by a spring 

 catch (see fig. 42), a sufficient resistance is doubly secured. 



TJue lock has been already described as being contained 

 within the breech-plug, and therefore its actions must be of 

 small size and of simple construction. Independently of the 

 plug which contains them, it may be said to consist of four 

 actions: 1st, the needle (fig. 43); 2nd, the mainspring 

 (fig. 44) ; Srdly, the screw cam (fig. 45), which drives the 

 needle back; and 4thly, the scear (fig. 46 a c), which holds 

 it ready for the trigger. There is also a bolt (fig. 47), which 

 is intended to act as a substitute for the " half-cock" of the 

 ordinary lock, and which j _j 5 



really is quite as efficient 

 in preventing danger. The 

 needle (tig. 43) consists of a 

 three parts a centre and 

 two extremities. The THE NEEDLE. (HALF SIZE.) 



front is a mere needle a 



about a line in diameter, and terminating in a sharp cutting 

 point, which readily pierces the paper base of the cartridge. 

 The middle receives this needle, and consists of two flat 

 shoulders or wings standing out from a strong pillar (see b), 



