Q. Explain the action of the combination fuse and name parts.
A. Before firing a hole is punched through the hole on the time-cone corresponding to time of flight at which it is desired that the projectile burst. On firing, the time-plunger strikes the firing-pin for the time-train, then the time-train begins to burn from the point where the hole in the cone was made, and at the end of the time of flight the flame reaches the interior of the fuse, thence to the shell. If this fails or it be desired to use the fuse as a percussion-fuse, the action is as in an ordinary percussion-fuse. Combination fuses are now always made with the centrifugal arming device as in percussion. (See Figs. 40 and 42.)
Q. What is a delayed-action fuse?
A. One which does not explode until a short time after striking.
Q. Explain the action of the new centrifugal fuse.
A. This fuse can act only when a rotary motion is given to it. This rotary motion, due to the rotating band, causes the plunger to bulge away from the center into two parts; when these parts separate it is seen from Fig. 41 that the firing-pin takes up a position parallel to the longer axis of the fuse and its point is almost touching the friction composition. When the projectile strikes, the plunger drives the firing-pin into the friction composition. The action is then the same as in the ordinary percussion-fuse. This fuse is therefore perfectly safe to handle, transport, or use. It becomes active only when a high rotary motion is given it. (See Figs. 41 and 42.)
Q. How are drill-primers loaded?
A. Insert a serrated wire with friction-pellet in the body of the primer, hold it in position with the assembling-tool, screw a rear wire or bottom wire (depending on whether it is an old- or new-model vent) fast to the serrated wire, fill with musket-powder, and close with a brass closing-cup, using the assembling-tool.
Q. Name the different kinds of projectiles in the United States service.
A. Solid shot, cored shot, shell, shrapnel, and canister. (See Fig. 43.)