Breech-sight

In gunnery, an instrument having a graduated scale of tangents by means of which any elevation may be given to a piece. Correctly speaking, the breech-sight gives the angle made by the line of aim or sight with the axis of the piece. The base of the breech-sight is a plate of bra curved to fit the base-ring or line, the scale and slides are similar to those of the pendulum hau e except that a hole is made in the plate, instead of a notch to sight through. Breech-sights are graduated for no disparts , a front-sight equal in height to the dispart being screwed into the top of the muzzle; in the Rodman guns, into the seat provided for the purpose between the trunnions. Breech-sights are also frequently held in sockets, and when the front-sight is placed on the trunnion, the socket is on the side of the breech. The pendulum hau e (see Hau e ) is a breech-sight used for field-guns to correct the error arising from difference of level in the wheels of the carriage. The Quinan breech-sight (invented by Lieut. W. R. Quinan, 4th U. S. Artillery) is an improvement on the pendulum hau e. It is fixed in a socket on the right side of the breech. The scale has a spirit-level, by means of which it is made vertical. The front sight is a short tube with cro -hairs fixed in it. The advantages claimed over the hau e are increased steadine and accuracy.