68 
INDUCTION SHOCKS 
matically either the make shocks or the break shocks at 
the will of the operator. The instrument under con- 
sideration lends itself so readily to the incorporation of 
such a device that I shall 
include a brief descrip- 
tion of one, believing 
that the value of the key 
is enough enhanced 
thereby to justify its 
inclusion. The entire 
mechanism, shown in 
ground plan in Fig. 13, 
is mounted upon a slab 
of vulcanite, which in 
turn rests upon a base 
of soapstone, slate, or 
other suitable material. 
The vulcanite is cut a- 
(Eh 
(0) 
FIG. 14. Diagram of the short- 
circuiting device. /, brass bar, 
rotating horizontally about axis, way between and under- 
u and bearing mercury cup, o, neath the leye k and 
which is in electrical communi- 
cation with post, p. z, z' ', platinum k , as indicated at s (Fig. 
pins mounted upon levers, k, k', 
and in electrical communication 
with post, p'. 
13). A brass rod, t 
(Fig. 14), is mounted 
upon an axis, u, in such 
fashion that it can be rotated horizontally about this axis 
within the confines of the space, s. At the end of the rod 
is a mercury cup, o. Two binding posts, p and p f , stand 
