IMPROVEMENTS IN ELECTRIC TELEGRAPHS, AND IN TELEGRAPHIC CABLES OR CONDUCTORS FOR THE CONDUCTING OF ELECTRICITY IN SUBMARINE AND UNDERGROUND TELEGRAPHS
Year: 1858

page_text: PROVISIONAL SPECIFICATION left by John Tatlock at the Office of the
Commissioners of Patents, with his Petition, on the 9th October 1858.
I, JOHN TATLOCK, of Flookersbrook, near to the City of Chester, in the
County of Chester, Gentleman, do hereby declare the nature of the Inven-
tion for "IMPROVEMENTS IN ELECTRIC TELEGRAPHS, AND IN TELEGRAPHIC CABLES OR
CONDUCTORS FOR THE CONDUCTING OF ELECTRICITY IN SUBMARINE AND UNDERGROUND
TELEGRAPHS," to be as follows:-
My improvement in telegraphic conductors or cables for submarine and
underground telegraphs is intended to obviate the influence produced by the
action of (what is usually termed) the "induced current," and which is
supposed to be induced by the passage of the current transmitted from the
voltaic battery (or other apparatus used for generating the current by which
signals are effected) along the conducting wire when it is insulated from the
surrounding water or earth.
For effecting this object I make the conductor altogether of metal instead
of employing the earth or water for half the conductor, which is commonly
termed "the earth circuit." I employ two metallic conductors or wires which
I separately enclose in and surround with gutta percha, or other insulating
material, so that these conductors are insulated from the surrounding earth or
water, and as a matter of course from each other. The electric or magnetic
current used in telegraphing is by this means capable of being transmitted and
returned through an insulating metallic conductor wholly, instead of being
transmitted and returned (as in the method now in use) partially through an
insulated conductor and partially by water or earth or other uninsulated

page_text: conductor. These conductors are of course attached to telegraphic instruments
for transmitting and receiving signals.
By the adoption of my improvement there is no metallic. or conducting
communication between the earth or water and the insulated wires or con-
ductors, consequently there is no metallic communication or conductor,
whereby the induced current can travel from one side of the insulating medium
to the other side; nor can any transmission of the induced current through
the telegraphic instruments or indicators take place.
Strands of wires may be used (as in the case of the Atlantic cable) instead
of single wires for the transmission and return of the electric or voltaic current,
it being, however, necessary to insulate such strands (as I have before
mentioned with reference to the single wires), so that there may be no con-
ducting medium between the inside and outside of insulating medium, and
also that the current should be wholly transmitted.and returned by an insulated
conductor, as before described.
The insulation of the conductors must be sufficient to prevent the induced
current penetrating the insulating medium, and the amount of insulation must
be regulated by the length and size of the conductors and the strength of the
battery power employed.
If thought desirable at any time to cause a transmission of the induced
current, a communication can be established by connecting the conductors at
both ends thereof with the earth or water. This may be done without passing
the induced current through the indicating apparatus. For this purpose a
signal agreed upon may be sent to the receiving station, so that the receiver
may know when to disconnect the indicating apparatus from the conductors,
and connect the conductors with the earth or water.
The second part of my improvements relates to electric telegraph indicators
or instruments, and is designed for the purpose of better developing the power
of the electric current. Instead of taking one continuous wire from the con-
ducting wire, and forming the coil (which passes over the magnetized needle in
the ordinary needle telegraph), I take two wires, each from the conducting
wire, and lap one over each side of the magnetized needle, leaving room for
the needle to oscillate inside the coil. By so doing, the coil is in two halves.
I also, in some cases (where from the strength and nature of the current it
may be found advantageous so to do) employ two or more coils placed behind
each other; and in that case I take four wires from the conducting wire to
form the two coils, and so on, in proportion to the number of coils. Three or
more magnetized needles may be employed, namely, one within each coil, and
one before and one behind each coil; all such needles being fixed on one axle.

page_text: I do not, however, claim as any part of my Invention or improvement the
using of more needles than one. It must also be understood that more needles
or coils than one will not always be advantageous, as increased friction will be
caused by employing two or more needles instead of one, and the number of
coils and needles must therefore be regulated by the strength and intensity of
the current employed. I wish it also to be understood that I do not claim as
any part of my Invention or improvement the use of more wires than one in
the making of coils and galvanometers, except when such wires are used in
the manner I have before described.
The third part of my improvements relates to those cases where it may be
found desirable to telegraph by transmitting the electric current always along
the same conductor and allowing it to return along the other conductor,
whether insulated or not. In this case I use three batteries or currents, which
for the sake of distinction I hereinafter call respectively a, b, and c; I arrange
the magnetized needle in such a position in relation to the indicating needle, that
whilst the currents a and b are employed in passing over the coil in which the
magnetized needle oscillates, the indicating needle shall hang vertical or in a
perpendicular position, and the magnetized needle shall be inclined at an angle
to it; then by withdrawing one of the currents b, the magnetized needle will
incline more towards a vertical or perpendicular position, and so cause the
indicating needle to move from its normal position to an angle in one direction,
being restored to its vertical or perpendicular position upon the current 6 being
again attached. When the third current c is brought into connection with
the instrument (so that the three currents a, b, and c, are employed), the
magnetized needle will be inclined in a still more angular position than when
the currents a and 6 only are used, and consequently the indicating needle will
be carried to an angle on the opposite side to that to which it turned when the
current a only was employed. Thus two motions can be given to the needle in
opposite directions, and by arranging a code of signals, messages may be
transmitted.
In using this form of telegraph it will be necessary that the magnetized and
indicating needles shall be fixed on the same axis, and that whilst telegraphing,
the current a should be transmitted continuously along the wire, and that the
current 6 should only be removed and the current c added (in manner herein-
before explained) when it is required to cause signals to be transmitted.