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.
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