MR. NEEDHAM'S NEEDLE GUN. 273 



bolt. The scear a is much smaller than in the common lock, 

 and is a catch of the most simple description pressed down into 

 its place by the spring b, and working upon the centre c. 

 As in the old lock it has a projecting arm which catches the 

 trigger, but since it must be pushed down instead of up, the 

 trigger requires to be of a somewhat different construction in 

 order to accomplish the liberation of the needle. This is 

 effected by carrying forward a lever in the trigger (see fig. 

 46, in which this is represented at d), ready to depress the 

 arm of the scear below it when the trigger is pulled. From 

 the want of room to play, and the consequent small size of 

 scear, there is not the freedom of action to be found in the 

 old locks, which will be missed by those who are fond of 

 handling them and making them " speak." This, however, 

 is a mere fancy; and so long as the lock does its duty with 

 safety and efficiency, it is little consequence whether it is 

 musical or not. Lastly, the bolt (fig. 47) is to be described 

 as follows : 



It is made in the form of a short screw, ter- 

 minating within in a sharp wedge, and without j> l( . ^j 

 in a lever about an inch in length. The bolt 

 is inserted in its place by screwing it in till it ( HALF S1ZE ' \ 

 reaches its bearings; when home, a little pro- 

 jecting knob traverses a smooth surface, slightly rounded, on 

 the outside of the lock, so that when the lever is either raised 

 or depressed, it is held firmly in that position. On comparing 

 the shape of the wedge at the end of the screw with the 

 notches in the needle, when the old plan of stop is adopted, 

 it will at once be seen that when the former is raised, this 

 wedge lies in the axis of the needle, and allows the longi- 

 tudinal notch to traverse freely upon it, while on depressing 

 it after the needle is caught by the scear, this same wedge 

 acts as a secure catch upon the third notch of the needle, and 

 prevents its being liberated on the pulling of the trigger. 

 When the scear is bolted instead of the needle, the catch 

 merely drops into a notch in it, but in either case, when these 

 parts are in good order, and the bolt is lowered so as to show 

 the word BOLTED, as in fig. 39, the lock is as safe as need 

 be, and I believe that there is far less danger than in the 

 ordinary lock at half-cock, because there is no chance of Mr. 



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