IMPROVEMENTS IN ELECTRIC TELEGRAPHS
Year: 1870

page_text: PROVISIONAL SPECIFICATION left by Henry Brown Greenwood at
the Office of the Commissioners of Patents, with his Petition, on the
25th January 1870.
I, HENRY BROWN GREENWOOD, of No. 8, Minson Road, Morris Park,
South Hackney, in the County of Middlesex, do hereby declaro the
nature of the said Invention for "IMPROVEMENTS IN ELECTRIC TELEGRAPHS,"
to be as follows:-
This Invention has mainly for its object the transmission from one
place to another of a facsimile of a written message. For this purpose
the message to be transmitted is written with a pointed instrument on
metal foil covered with a non-conducting substance. In writing the
message on this prepared surface with the pointed instrument the non-
conducting substance is by it removed from the metallic surface. The
message may either be written in ordinary letters or in symbols to
represent them. The metal foil is fastened around the circumference
of a metallic drum, which when the message is being transmitted is
caused to revolve continuously. A metallic point is caused to bear

page_text: upon the surface of the foil which is fixed around the drum, and a slow
sideway movement is given to this point in the direction of the axis of
the drum, or this motion might be given to the drum itself. The point
and the drum are coupled up to a battery and to a telegraph wire in
such manner that when the point comes in contact with a portion of the
metal foil from which the non-conducting substance has been removed
an electric current will be transmitted through the wire.
This transmitting instrument is similar to transmitting instruments
heretofore proposed, but in order to record the transmission of the signals
at the opposite end of the wire I employ the following arrangement of
recording apparatus:-The electric currents from the line wire are
caused to circulate through the coils of an electro-magnet. The armature
of the magnet is carried on one arm of a lever; on the other arm of this
lever is carried a small reservoir for containing ink or marking fluid, the
bottom of the reservoir is contracted to a fine tube, which is open at
the bottom, the open end of the tube being so small as not to permit
the fluid to drop out therefrom. When the armature is drawn towards
the magnet it causes the pointed end of the ink vessel to bear against
the surface of a sheet or strip of paper fastened around the circumference
of a drum which is caused to revolve continuously at the same surface
speed as the drum of the transmitting instrument, and either the drum
or the ink vessel has a sideway motion given to it to correspond with the
sideway motion given to the metallic point or drum of the transmitting
instrument. When the open end of the ink vessel bears against the
surface of the paper, the paper is marked with the ink or fluid, and in order
to insure that there shall at all times be a flow of ink from the reservoir
to the extremity of its pointed end I pass down through the reservoir a
thin wire and allow its end to protrude somewhat beyond the open
pointed end of the reservoir. The portion of the wire within the reservoir
is formed into or connected with a spring, so that when the pointed end
of the reservoir is forced against the paper the wire may yield and allow
its end which previously projected somewhat beyond the point to move
back within it. When the point is again drawn back from the paper
the end of the wire again moves out from the point and carries along
with it a small quantity of marking fluid to be ready to mark upon the
paper when the point is again forced down on to it, I prefer to construct
each instrument in such manner that it shall act both as a recording and
transmitting instrument; a marking instrument such as above described

page_text: and also a metallic point being arranged to work in conjunction with
the same revolving drum.
The recording instrument above described is also applicable for
recording the transmission of electric currents through telegraph wires
by arrangements of transmitting instruments' such as are now commonly
employed for working with other descriptions of recording instruments.