dispart-sight

Sights should invariably be made so that the level line on the stem will correspond with the bottom of the head when it rests on the sight-box, and thus secure a dispart-sight in case of accident to the screw in the sight-box.

Ordnance Instructions for the United States Navy. 1866. Fourth edition. United States. Navy Dept. Bureau of Ordnance

In case the ordinary sights should be lost or rendered useless, tangent firing may be resorted to against ships, by pointing with the wooden dispart-sight at such part of the ship as the Tables indicate for the distance, and according to the class of gun in use at the time.

Ordnance Instructions for the United States Navy. 1866. Fourth edition. United States. Navy Dept. Bureau of Ordnance

Half the difference between the diameters of the gun at the base-ring and swell of the muzzle, or at any intermediate point on the line of metal, will give the proper height of the dispart-sight at the point where the least diameter was taken, to which must be added the height of the lock-piece above the base-ring, in order to get a line of sight over it, parallel to the axis of the bore.

Ordnance Instructions for the United States Navy. 1866. Fourth edition. United States. Navy Dept. Bureau of Ordnance