IMPROVEMENTS IN THE MEANS OF TRANSMITTING ELECTRIC CURRENTS FOR TELEGRAPHIC AND OTHER PURPOSES
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Thomas Walker at the Office of
the Commissioners of Patents, with his Petition, on the 23rd January
1874.
I, THOMAS WALKER, of No. 65, Robert Street, Chelsea, in the County
of Middlesex, do hereby declare the nature of the said Invention for
" IMPROVEMENTS IN THE MEANS OF TRANSMITTING ELECTRIC CURRENTS FOR
TELEGRAPHIC AND OTHER PURPOSES," to be as follows:-
:-
My Invention relates to means of rendering uninsulated or partially
insulated wires available for transmitting electric currents for telegraphy
and other purposes, and to the partial insulation and protection by
For the
inexpensive materials of wires employed in this manner.
purpose of rendering an uninsulated or partially insulated wire available
as a conductor or telegraphic line wire I interpose between the receiving
instrument which is to be operated by currents transmitted by the wire
and the near end of the line wire, a battery, preferably consisting of
iron for the one pole, and of some less oxidisable metal, such as copper
or platinised silver, for the other pole. The line wire being connected to
the iron pole of this battery, and the receiving instrument being con-
nected to the other pole, electric currents sent into the line wire at its

page_text: distant end will be transmitted to the receiving instrument, notwith-
standing the defective insulation of the line wire.
For considerable lengths of line wire, and also in cases where it has
to branch off to different receiving instruments, several batteries such as
I have described may be interposed in the course of the line wire.
As a single line wire is generally made to serve for the transmission
of currents in both directions, and is therefore made capable of being
connected at each of its ends to both a sending and a receiving
instrument, I employ a battery as I have described above at each end
of the line, and by means of commutators or bridges of any known
construction I bring either battery into circuit when the receiving
instrument next to it is to be employed.
In the manner above set forth electric currents may be transmitted by
imperfectly insulated conductors for blasting or other purposes to which
such currents are ordinarily applied.
Although by the arrangement which I have described a wire without
any insulation whatever may be made available as a telegraphic line
wire, yet the action of such a wire as a conductor can be very much
improved by partially insulating it by the use of inexpensive materials
which serve at the same time to protect the wire against corrosion. In
order to provide such insulation and protection I employ a mixture of
shellac, rosin, and tar, or of rosin, tar, and oil, to which may be added
pitch or asphaltum, which mixture I apply as a thick paint to the wire;
or I make the mixture of a more solid consistency, and apply it to the
wire by means of a die, in the manner in which the india-rubber or
gutta percha covering is usually applied to electric wires.
In order the better to secure the adhesion of the coating to the wire,
and also to render it more strong and durable as a protector, I prefer to
cover the wire with tape or fibre, saturated with the insulating mixture
before its application to the wire, or served therewith after it has been
put on the wire.