IMPROVE- MENTS IN TELEGRAPHY
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Peter Jensen at the Office of the
Commissioners of Patents on the 9th January 1882. A communication
from abroad by Francis Wiley Jones, a Citizen of the United States of America,
residing at New York, in the State and County of New York United States
of America.
PETER JENSEN, of 33 Chancery Lane in the County of Middlesex. " IMPROVE-
MENTS IN TELEGRAPHY." (A communication from abroad by Francis Wiley Jones,
a Citizen of the United States of America, residing at New York, in the State and
County of New York United States of America.)
This Invention relates especially to duplex cable telegraphs, and the object is to
provide an efficient means for overcoming the disturbing effects of the electrical
discharge from the cable upon the receiving instrument at the home or sending
station.
This Invention has, as a further object, the avoidance of certain difficulties that
exist when a check or neutralizer for the static discharge consisting of an electro-
magnetic coil, placed directly in the main circuit, is employed.
The phenomenon of charge and discharge of telegraph lines, is a well known
one, but the difficulties arising therefrom are most felt in submarine telegraphy.
When a submarine telegraph is duplexed, the discharge which occurs when the
transmitting key is raised, after the completion of a signal, affects the receiving
instrument at the transmitting station, and mutilates and renders unintelligible the
signals coming from the distint station. To meet this difficulty Mr. C. F. Varley
in 1870, proposed to place an electro magnetic coil directly in the main line circuit
at each station, and between the receiving instrument and the main line itself, the
design being to meet and neutralize the static discharge from the line, by the extra
current set up in the electro-magnetic coils at the moment of the change of
current, produced by the raising of the transmitting key or the restoration of the
transmitting apparatus to its uorinal condition after the completion of a signal,
the extra current thus set up being as is well understood in the same direction as
the current by which the coils are charged, and therefore in an opposite direction
to the current of discharge from the cable. This arrangement but imperfectly
accomplishes the object. The extra current set up in the coil is liable to interfere

page_text: with the proper operation of the receiving instrument at the distant end. The
coil moreover opposes a resistance to the transmitted currents and in the
position proposed, for it is a source of disturbance. The aim of this Invention is to
overcome the difficulties existing, by placing the electro-magnetic coils in a branch
to carth form the main line wire said branch passing off at a point between the
transmitter and the main line, and by employing a series of graduated electro-
magnetic coils with equivalent branches around them, so that the extra or
neutralizing current may be adjusted to the varying static condition of the line
and consequent variations in the duration and electro-motive force of the discharge
current, without disturbing the adjustment of the electrical balance employed for
the time being for preventing the outgoing signals from affecting the receiving
instruments at the sending station.
As applied to duplex arrangement for cable working known as the "Varley"
cable duplex the Invention may be applied as follows:-The condenser and the
receiving mirror galvanometer or other receiving instrument are placed in the
bridge wire at the station at one end of a cable. The non induction resistances
are formed by first doubling the wire of which they are made, and then winding
the same in the ordinary way. These resistances are adjustable and adjusted in
the well known manner to render the effects of the outgoing signals inappreciable
in the receiving galvanometer. These resistances are of course to be adjusted with
reference to the joint resistance of the cable and the branch from the main line to
earth containing the neutralizing electro-magnets.
The main line or signalling battery, and the transmitting or reversing key may
be arranged as usual. At the point where the bridge wire joins the main line,
or at some point near thereto, is connected a branch wire leading to earth through
a non-inductive resistance, and containing the series of electro-magnetic coils of
graduated size and capacity and each containing a bar of soft iron making them in
fact electro-magnets. These electro-magnets may be either straight electro-magnets
or horse-shoe electro-magnets with armatures bridging their poles, so as to form
their cores into closed magnetic circuits. The latter plan results in giving an
increased duration to the extra current set up in the coils, owing to the tardiness
with which the cores lose their magnetism. Each coil is constructed to give a
determinate electro-motive force of extra current, this being of course dependent
upon the length of the coil. The duration of the extra current set up may be
varied by making the cores longer or shorter or by bridging the poles to a greater
or less extent. Non-inductive resistances are connected to this branch and are
adjusted to equal the resistances of the coils or helices of the several electro-magnets,
and arranged in connection with switches for breaking the circuit through the
electro-magnet coils and substituting the connection through the resistances. By
this means any number or combination of the electro-magnetic coils can be included
in the branch wire leading to earth, so as to adjust the extra current produced in
the branch wire, to the varying condition of the cable, and the consequent variations
This is more-
in the strength or duration of the discharge current from the cable.
over accomplished without varying the resistance in the branch, since as will be
readily seen, when an electro-magnetic coil is cut out an equivalent resistance is
substituted so that an adjustment of the coil apparatus to produce a different
strength or duration of extra neutralizing current will not necessitate a re-adjust-
ment of the balancing resistances. There is also a switch adapted to close through
a resistance, a leak circuit taken from the branch wire at any one of a number of
points along said branch wire.
The resistance
beyond the electro-magnetic coils in the branch leading to earth enables the operator
to adjust the amount of current flowing through the said electro-mgnetic coils.
This resistance when set cannot evidently be disturbed without disturbing the
balance.
This arrangement of apparatus is operated in the ordinary way.
Outgoing signals sent by the transmitter do not affect the receiver, the bridge
wire being at a neutral point with relation to the outgoing current. A portion of

page_text: the outgoing current flows through the branch to earth, through the electro-
magnetic coils, and in a certain direction.
The current to line flows in the same direction and charges the line.
When the transmitter is restored to its normal position a discharge current flows
back from line in the opposite direction to the charging current, and at the inter-
secting point of the bridge wire and the cable wire a portion passes to the bridge
wire and would produce a false signal in the receiving instrument, were it not for
the extra current set up in the branch wire at the same time, which, under the
supposed conditions would be in the same direction as the charging current and
therefore in the direction along the branch to earth. As is obvious this current a
portion of which will also affect the bridge wire, will if properly adjusted as to
duration and strength perfectly neutralize the effects of the discharge current from
the cable.
This Invention is applicable not only to cable but to land lines, and to other
duplex arrangements besides that described, as for instance to the ordinary
differential system.