A little
trigger, B, which you can cut out of sheet brass, is pivoted at a, where it
must be raised off the base by a small washer. It projects 1/4 inch beyond
the base on the gong support side. A square nick is cut in it at such a
distance from a that, when the wire spike on C is in the nick, the strip is
held clear of T2. The other end of the trigger, when the trigger is set,
must be 1/8 inch from the shank of the alarm hammer--at any rate not so
far away that the hammer, when it vibrates, cannot release C from the nick.
To fix the base on to the top of the clock, the works must be removed
(quite an easy matter to accomplish) and holes bored for a couple of screws
put through from the inside. If the underside of the base is not quite
correctly curved, take care not to force in the screws far enough to
distort the barrel. It is advisable to do the fitting of the parts of the
release after the base has been fixed, and before the works are replaced.
The position of the hammer shaft can be gauged accurately enough from the
slot in the case.
The tails of the terminals T1 T2 must be truncated sufficiently not to
penetrate the base and make contact with the barrel, or a "short circuit"
will be evident as soon as the battery is connected up.
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