n
induction telegraphy (two years before the publication of the work of
Hertz), but the patent (No. 465,971) was not issued until December
29, 1891. In 1903 it was purchased from him by the Marconi Wireless
Telegraph Company. Edison has always had a great admiration for Marconi
and his work, and a warm friendship exists between the two men. During
the formative period of the Marconi Company attempts were made to
influence Edison to sell this patent to an opposing concern, but his
regard for Marconi and belief in the fundamental nature of his work were
so strong that he refused flatly, because in the hands of an enemy the
patent might be used inimically to Marconi's interests.

Edison's ideas, as expressed in the specifications of this patent, show
very clearly the close analogy of his system to that now in vogue.
As they were filed in the Patent Office several years before the
possibility of wireless telegraphy was suspected, it will undoubtedly be
of interest to give the following extract therefrom:

"I have discovered that if sufficient elevation be obtained to overcome
the curvature of the earth's surface and to reduce to the minimum the
earth's absorption, electric telegraphing or signalling between
distant points can be carried on by induction without the use of wires
connecting such distant points. This discovery is especially applicable
to telegraphing across bodies of water, thus avoiding the use of
submarine cables, or for communicating between vessels at sea, or
between vessels at sea and points on land, but it is also applicable
to electric communication between distant points on land, it being
necessary, however, on land (with the exception of communication over
open prairie) to increase the elevation in order to reduce to the
minimum the induction-absorbing effect of houses, trees, and elevations
in the land itself. At sea from an elevation of one hundred feet I can
communicate electrically a great distance, and since this elevation
or one sufficiently high can be had by utilizing the masts of ships,
signals can be sent and received between ships separated a considerable
distance, and by repeating the signals from ship to ship communication
can be established between points at any distance apart or across the
largest seas and even oceans. The collision of ships in fogs can be
prevented by this character of signalling, by the use of which, also,
the safety of a ship in approaching a dangerous coast in fog