Both percussion and time fuses are used in the shells of all calibres. The percussion fuse consists of a plunger having a fire-hole through the centre and surmounted by a pointed anvil. This is dropped into the fuse-hole of the shell, and hangs on a shoulder in the wall of the fuse-hole. Even with the point of the anvil a hole is bored through the wall of the shell horizontally, into which a pin is inserted whose inner end covers the anvil and keeps it from going forward. A gun-metal case screws into the end of the fuze-hole, and into this screws a small cap carrying the fulminating composition. When the gun is fired the centrifugal force throws the pin out, and when the projectile strikes the plunger rides forward against the fulminate and explodes it. The fulminate-cap and the pin are not inserted until the projectile is brought to the gun, the mouth of the fuse-hole being kept sealed by a wafer. The Krupp time-fuse consists of a gun-metal body which screws into the fuse-hole and has two chambers. The lower one, containing the blowing-charge, opens into the shell. It is solid to the rear, except a diagonal channel on one side which is pierced up and opens on a small table which carries the fuse-composition disc. The latter is circular and on the principle of the Bormann fuse, its exterior wall being marked for seconds and fractions. The upper chamber of the fuse is open at its upper extremity and closed at the lower, except several side channels leading to the composition disc. In the bottom of this chamber is a pointed anvil. The fuse-cap is ogival and screws over the tipper chamber, fitting tightly down on the composition disc. In this cap is a plunger loaded with fulminating composition at its lower end, and suspended by five small tenons. The composition is ignited by the percussion part of the fuse on firing. A safety-pin passes through the fuse-cap and plunger, and is withdrawn when the shell is brought to the gun. [Illustration: German Time-Fuse.] PRIMERS. Friction primers are used altogether. These are of the same type as those used with English guns. (See English Ordnance.) SIGHTS. [Illustration: Sight-Bush and Clamp.] [Illustration: Rear-Sight.] [Illustration: Front-Sight.] [Illustration: Rear-Sight for Light Guns.]