case, in order that the contact may be continuous and that the bell may be
rung, the piece, A, upon falling, sets up a permanent contact with the
part, _a_ (Fig. 3).

[Illustration: FIG. 5.--BRASSART'S SEISMIC CLOCK.]

_Brassart's Seismic Clock._--This apparatus is designed for being put in
connection at a distance with an indicator like the ones just described.
It is a simple clock to which a few special devices have been added.
Seismic clocks may be classed in two categories, according as they are
stopped by the effect of a shock or are set running at the very instant
one occurs. The Messrs. Brassart have always given preference to those of
the second category, because there is no need of watching them during a
seismic calm, and because they are much more easily constructed. It is to
this class, then, that their seismic clock belongs. It is capable of being
used for domestic purposes in place of any other clock, and of becoming a
seismoscopic clock as soon as it is put in electric communication with the
seismic telltales.

To the cross-piece that holds the axle of the drums the inventors have
added (Fig. 5) a support formed of a strip of brass, S, with whose
extremity is jointed (at the lower part) a double lever, A. This latter is
held in a horizontal position by a small counterpoise, _i_, so that the
finger at the opposite extremity shall prevent the pendulum, P, from
swinging. To keep the latter in a position of rest a bent lever, _n n'_,
is jointed to the upper part of the support, S. The longer arm, _n'_, of
this lever is bent forward at right angles, so that it may come into
contact with and repel the small rod of the pendulum as soon as the lever
has been lifted by means of a small cord which is connected with the
larger arm, _n_, and runs up to a small hook, from whence it descends and