The base fuze shown in Pamphlet No. 4, Fig. 15, is typical of the fuzes met with in 7.5 cm, 8.8 cm and 10.5 cm armour-piercing shell, and has a screw-threaded recess in the base of the body in which a tracer is screwed. The following types of tracers have been met with:–

The type shown in Fig. 8 "A" consists of a steel body in the form of a hollow cylinder with an external screwthread for insertion in the fuze. The body contains in inverted cup of copper-plated steel. The cup contains 197 grains of tracing composition primed with 30 grains of priming composition. The tracing composition is pressed in three increments. Both the tracing and priming compositions are pres-sed with a serrated drift. The tracing composition consists of beeswax, barium nitrate and magnesium, and produces a brilliant white trace. The priming composition consists of barium peroxide, barium carbonate and magnesium. The tracer is lightly closed at the base by a convex celluloid disc held bet-ween an internal flange in the body and the mouth of the cup.

The type shown in Fig. 8 "B" has the body closed at the front end by a steel disc and is fitted with a steel liner instead of a cup. The tracing composition, with a weight of 185 grains, is pressed in two increments and contains shellac instead of beeswax. The 62 grain priming composition is pressed in two increments and has the same composition as that as the first type. The tracer is closed by a flat celluloid disc let into the undercut recess.

The type shown in Fig. 8 "C" consists of a steel body in the form of an inverted flanged cup with an external screwthread for insertion in the fuze. The body contains an inverted steel cup containing 157 grains of tracing composition pressed with a serrated drift and 46 grains of priming composition pressed with an eight-sided tapering drift. The tracing and priming composition are the same as those given for the first type. The body is clos-ing by a flat celluloid disc secured by a steel collar screwed into the body.