Below is an extract from Gibbons manual:
United States Sea -coast Fuze .- In the United States, a bronze fuze -plug has been adopted
for use with heavy shells, instead of the wooden one. It, however, fits the eye in the same
way, and is retained by friction.
It having been found that ricochets, more especially over water, were very apt to extinguish
these fuzes, a safety -cap and primer combined, have
been adopted in the navy, and found to succeed very
well, Fig. 188. A recess in the top is filled with priming
composition and covered, until the fuze
is required for use, with a leaden disk which fits
accurately the opening. A crooked passage filled with
the priming conveys the fire to the fuze -composition
beneath, and prevents water from being forced in, at
least in sufficient quantity to extinguish the fuze.
Another modification adds to the security of the fuze,
and removes one great objection to the use and storage
of loaded shells on ship -board. This consists of a small
leaden plug, A, Fig. 188, which fits the interior end of
the fuze-plug, and remains t here until the shell is fired,
when the shock of the explosion forces it out by blowing
the less dense shell away from it, exactly as it is stated a recent powder -explosion in the
streets of Wilmington, Del., blew the horses away from the shoes on their feet. No shock
less than that from a charge of powder is sufficient to produce this result, so that even were
the shell dropped from a considerable height on the end of the diameter opposite to the
fuze-hole, the plug would not leave its position. Or if, by any accident, the leaden disk of the
primer should be displaced, and the fuze take fire, the shell would not explode. In view of
the increased danger on board ship, and the terrible accidents which have happened from
shells, this improvement is a most important one. By means of it the shells can be loaded,
the fuzes set, and nothing remains to be done except to remove the leaden disk of the primer
when the shell is placed in the gun. The importance of the safety -primer is seen when it is
stated that four out of five fuzes are extinguished by ricocheting on the water.
Regards,
John aka Bart
