Page 283 - My FlipBook

INTRODUCTION OF THE GOLD. 281

teen blows per second. The force of the blow can be modified at will
by an extremely simple contrivance, as follows : The interdigitations
seen around the upper end of the sleeve are held together by means of
a spring attached to the sleeve. Pulling the sleeve away from the head
against the spring, and revolving it to the right or left, raises or lowers
the head of the plunger. Upon releasing the sleeve the spring at once
throws it back to engage with the head, and the blow is heavier or
lighter, according to the direction in which the sleeve has been revolved.
The impacting power of the blow from this is great, and in the
hands of an experienced operator a large quantity of gold can be con-

FiG. 233.

Webb's set.

Chapiiell's set.
densed in a short space of time. When cohesive gold foil is employed
smooth oval points may be used M'ith most satisfactory results. The
point should not be pressed hard against the filling, but a skimming or
smoothing motion given to the instrument. The surface of the filling
when thus packed has a jwlished or planished appearance as if done
with a hand burnisher. Such fillings are usually of great density.
There are other mechanical mallets intended for use on the engine
which have what is known as a " cam " movement. They are not,