ground outside of the door, and with the staircases
of the gallery, so as to form separate exits above the regular
entrances.

IMPROVED ELECTRO-MAGNETIC DENTAL PLUGGER.

James E. Dexter, New York city.--This invention consists, first, in a
magnet having a centrally bored iron core, surrounded by a magnetic
coil, which is enveloped by an iron shell that is concentric with the
central core, and is attached to a flange formed on the lower end of
the said central core. One side of both shell and core are split for
the purpose of obviating residual magnetism. The invention also
consists in combining a spring yoke, a vibrator, and a spring contact
piece, as hereinafter particularly described. The third part of this
invention consists in the arrangement of the key for completing the
circuit, which is made with an insulating exterior, and is provided
with one of the termini of the magnet coil, and bears against the side
of the key to insure a constant contact of the surfaces. The various
parts of the plugger are combined, so that pressing the key with the
finger makes the circuit, and a succession of regular strokes is
produced, the force of which may be varied by an adjusting screw.

* * * * *

NEW MECHANICAL AND ENGINEERING INVENTIONS.

IMPROVED COTTON GIN.

Joseph W. Thorn, Iuka, Miss., assignor to himself and M.W. Beardsley,
of same place.--In this machine there is a new construction of the
brush drum for simplifying the same, and facilitating the application
of the brush wings, so that they can be readily taken off and put on;
also, an arrangement of the ribs between the saws for facilitating the
separating of the seed from the cotton without breaking and injuring
the fiber. There are also ingenious devices for preventing the seed
from gathering and clogging at the ends of the saw drum.

IMPROVED SAFETY CHECK FOR ELEVATORS.

Nathan H. Fogg, Boston, Mass.--When the car is suspended normally from
the rope, the rubber balls, arranged in sockets near the lower part of
the car, are supported on their seats in a state of rest; but the
instant that the rope breaks or gets detached from the bolt the action
of a spiral spring throws an actuating plate downward, and levers and
ball-carrying rods upward. The balls are thus thrown off their seats
and wedged between the inclined sides of the pockets and the guide
posts of the elevator so as to stop thereby the car.

IMPROVED COMB