ich shows that he realized the value of tungsten also for
this purpose. "Filaments of carbon placed in a combustion tube with a
little chloride ammonium. Chloride tungsten or titanium passed through
hot tube, depositing a film of metal on the carbon; or filaments of
zirconia oxide, or alumina or magnesia, thoria or other infusible oxides
mixed or separate, and obtained by moistening and squirting through a
die, are thus coated with above metals and used for incandescent lamps.
Osmium from a volatile compound of same thus deposited makes a filament
as good as carbon when in vacuo."

In 1888, long before there arose the actual necessity of duplicating
phonograph records so as to produce replicas in great numbers, Edison
described in one of his caveats a method and process much similar to
the one which was put into practice by him in later years. In the
same caveat he describes an invention whereby the power to indent on
a phonograph cylinder, instead of coming directly from the voice, is
caused by power derived from the rotation or movement of the phonogram
surface itself. He did not, however, follow up this invention and put it
into practice. Some twenty years later it was independently invented
and patented by another inventor. A further instance of this kind is
a method of telegraphy at sea by means of a diaphragm in a closed
port-hole flush with the side of the vessel, and actuated by a
steam-whistle which is controlled by a lever, similarly to a Morse key.
A receiving diaphragm is placed in another and near-by chamber, which is
provided with very sensitive stethoscopic ear-pieces, by which the
Morse characters sent from another vessel may be received. This was
also invented later by another inventor, and is in use to-day, but will
naturally be rivalled by wireless telegraphy. Still another instance
is seen in one of Edison's caveats, where he describes a method of
distilling liquids by means of internally applied heat through electric
conductors. Although Edison did not follow up the idea and take out a
patent, this system of distillation was later hit upon by others and is
in use at the present time.

In the foregoing pages of this chapter the authors have endeavored
to present very briefly a sketchy notion of the astounding range of
Edison's practical ideas, but they feel a sense of impotence in being
unable to deal adequately with the subject in the space that can be
devoted to it. To those who, like the authors,