gy weather
can be assured. In communicating between points on land, poles of great
height can be used, or captive balloons. At these elevated points,
whether upon the masts of ships, upon poles or balloons, condensing
surfaces of metal or other conductor of electricity are located. Each
condensing surface is connected with earth by an electrical conducting
wire. On land this earth connection would be one of usual character in
telegraphy. At sea the wire would run to one or more metal plates on the
bottom of the vessel, where the earth connection would be made with the
water. The high-resistance secondary circuit of an induction coil is
located in circuit between the condensing surface and the ground. The
primary circuit of the induction coil includes a battery and a device
for transmitting signals, which may be a revolving circuit-breaker
operated continually by a motor of any suitable kind, either electrical
or mechanical, and a key normally short-circuiting the circuit-breaker
or secondary coil. For receiving signals I locate in said circuit
between the condensing surface and the ground a diaphragm sounder, which
is preferably one of my electromotograph telephone receivers. The key
normally short-circuiting the revolving circuit-breaker, no impulses are
produced in the induction coil until the key is depressed, when a large
number of impulses are produced in the primary, and by means of the
secondary corresponding impulses or variations in tension are produced
at the elevated condensing surface, producing thereat electrostatic
impulses. These electrostatic impulses are transmitted inductively
to the elevated condensing surface at the distant point, and are made
audible by the electromotograph connected in the ground circuit with
such distant condensing surface."

The accompanying illustrations are reduced facsimiles of the drawings
attached to the above patent, No. 465,971.

V. THE ELECTROMOTOGRAPH

IN solving a problem that at the time was thought to be insurmountable,
and in the adaptability of its principles to the successful overcoming
of apparently insuperable difficulties subsequently arising in other
lines of work, this invention is one of the most remarkable of the many
that Edison has made in his long career as an inventor.

The object primarily sought to be accomplished was the repeating of
telegraphic signals from a distance without the aid of a galvanometer
or an electromagnetic relay, to overc