elligible speech in an ordinary Bell telephone receiver nearly passes
belief. The work done in lifting such an instrument from its hook to the
ear of the listener, would, if converted into electric energy, be
sufficient to maintain an audible sound in a telephone for 240,000
years! Even extremely attenuated waves may therefore produce audible
signals in such a receiver.

The electric motor was another gift of Faraday to commercial science,
although in this case there are others who can, perhaps, justly claim to
share the honor with him. Faraday's early electric motor consisted
essentially in a device whereby a movable conductor, suspended so as to
be capable of rotation around a magnet pole, was caused to rotate by the
mutual interaction of the magnetic fields of the active conductor and
the magnet. The magnet, which consisted of a bar of hardened steel, was
fixed in a cork stopper, which completely closed the end of an upright
glass tube. A small quantity of mercury was placed in the lower end of
the tube, so as to form a liquid contact for the lower end of a movable
wire, suspended so as to be capable of rotating at its lower extremity
about the axis of the tube. On the passage of an electric current
through the wire, a continuous rotary motion was produced in it, the
direction of which depends both on the direction of the current, and on
the polarity of the end of the magnet around which the rotation occurs.

The great value of the electric motor to the world is too evident to
need any proof. The number of purposes for which electric motors are now
employed is so great that the actual number of motors in daily use is
almost incredible, and every year sees this number rapidly increasing.

The above are the more important machines or devices that have been
directly derived from Faraday's great investigation as to the production
of electricity from magnetism. Let us now inquire briefly as to what
useful processes or industries have been rendered possible by the
existence of these machines.

Apparently one of the most marked requirements of our twentieth-century
civilization is that man shall be readily able to extend the day far
into the night. He can no longer go to sleep when the sun sets, and keep
abreast with his competitors. Of all artificial illuminants yet
employed, the arc and the incandescent electric lights are
unquestionably the best, whether from a sanitary, aesthetic, or truest
economical standpoint. Now