the counterpoise. The contact is thus kept up for some few minutes.
This apparatus works very satisfactorily, but is cumbersome and
relatively high-priced.

_The Brunot Controller as a Controller of the Passage of Trains._--The
Brunot Controller, which has been employed for several years on the
Railway of the North, is designed to control the regularity of the
running of trains, and to make automatically a contradictory
verification of the figures on the slips carried by the conductors. In
Fig. 11 we give a longitudinal section of the apparatus. It consists
of a wooden case containing a clockwork movement, H, upon the axle of
which is mounted a cardboard disk, C, divided into hours and minutes,
and regulated like a watch, that is to say, making one complete
revolution in twelve hours. The metallic pencil, c, which is capable
of displacing itself on the cardboard in a horizontal direction
opposite a groove on the other side of the disk, traces, when pressure
is brought to bear on it, a spiral curve. The transverse travel of
the pencil is effected in ninety-six hours. The displacement of the
pencil is brought about by means of a cam. Under the influence of the
jarring of the train in motion, a weight, P, suspended from a flexible
strip, l, strikes against the pencil, c, which traces a series of
points. During stoppages there is, of course, an interruption in the
tracing of the curve.

[Illustration: Fig. 11.--Brunot's Controller. RAILWAY APPARATUS AT THE
PARIS ELECTRICAL EXHIBITION.]

Up to this point no electricity is involved--the apparatus is simply a
controller of regularity. Mr. Brunot has conceived the idea of
utilizing his apparatus for controlling the passage of trains at