Mortar, Electric.
An electric toy which may have various modifications. In the cut a
wooden mortar with recess to receive a ball is shown. Two wires enter
the base but do not touch. On placing the ball in position and passing a
spark from a Leyden jar across the interval between the wires, the heat
and disturbance are enough to project the ball. Gunpowder may be used,
the discharge being passed through a wet string to prolong the spark.
Fig. 244. ELECTRIC MORTAR.
Motor, Compound or Compound Wound.
A motor which has two windings on the field magnets, one in parallel
with that on the armature, the other in series therewith, exactly as in
a compound dynamo. (See Dynamo, Compound.)
Motor, Differential.
A differentially wound motor; with a compound wound field, whose series
coil and shunt coil are wound in opposition to each other. It is
virtually a compound wound dynamo. (See Dynamo, Compound Wound.)
Motor, Electric.
A machine or apparatus for converting electric energy into mechanical
kinetic energy. The electric energy is generally of the dynamic or
current type, that is to say, of comparatively low potential and
continuous or virtually continuous flow. Some electrostatic motors have,
however, been made, and an influence machine can often be operated as a
static motor.
Electric motors of the current type may be divided into two
classes--direct current and alternating current motors.
Direct current motors are generally based on the same lines of
construction as dynamos. One of the great discoveries in modern
electricity was that if a current is passed through a dynamo, the
armature will rotate. This fact constitutes the principle of the
reversibility of the dynamo.