IMPROVEMENTS IN TELEGRAPHY
Year: 1885

page_text: "
I THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex Patent Agent do hereby declare the nature of this invention for
IMPROVEMENTS IN TELEGRAPHY" a communication to me from abroad by
Thomas Alva Edison of Menlo Park in the County of Middlesex and State of
New Jersey, United States of America, Inventor, to be as follows :--
The object of the Invention is to increase the capacity of local telegraph lines or
those lines having one or more way stations in addition to the terminal stations by
the production of apparatus by means of which two sets of independent and non-
interfering Morse signals can be sent back and forth over the line between terminal
stations or terminal and way stations or way stations alone.
In carrying out the Invention there are employed for receiving instruments at.
each terminal and way station an ordinary non-polarized relay which acts by
changes in the strength of current without regard to its polarity and a polarized
relay acting by changes in the polarity of current without regard to its strength.
The line is provided with a constant current from a main battery of a suitable
number of cells which is decreased by the manipulation of a Morse key at each
station such keys normally short circuiting a large resistance and throwing such
resistance into line when depressed. The non-polarized relays which respond to
this variation in current close sounder circuits at their back points.
In order to reverse the polarity of the constant line current without changing its
strength, there is provided at each terminal and way station, a battery, controlled
by the manipulation of a key, which battery has twice the number of cells of the
main battery, and which is thrown into circuit reverse to and opposing the main
battery. This local battery is normally out of circuit and when thrown in
neutralizes the current of main battery and produces a current of opposite polarity
equal to the normal current of the main battery. By these means it will be seen
the line current can be reversed at any station whether way or terminal thus
operating the polarized relay and without affecting the non-polarized relaya
Deted this 00nd den of Tune 100K

page_text: Improvements in Telegraphy.
I THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex, Patent Agent do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
The object of the invention is to increase the capacity of local telegraph lines or
those lines having one or more way stations in addition to the terminal stations,
by the production of apparatus by means of which two sets of independent and
non-interfering Morse signals can be sent back and forth over the line between
terminal stations or terminal and way stations or way stations alone.
In the drawing, the figure represents two terminal stations and a way station
having apparatus embodying the invention.
In carrying out the invention there are employed for receiving instruments at
each terminal and way station A, B, C, an ordinary non-polarized relay H, which
acts by changes in the strength of current without regard to its polarity, and a
polarized relay K, acting by changes in the polarity of current without regard to
its strength.
The line L, L, grounded at its ends as usual, is provided with a constant current
from a main battery M, B, of a suitable number of cells (for illustration 16 although
a less number is indicated diagrammatically in the drawing) which battery is
decreased by the manipulation of a Morse key D at each station, such keys
normally short-circuiting (as shown in the drawing) a large resistance R, (say
5000 ohms) and throwing such resistance into line when depressed. The non-
polarized relays H, which respond to this variation in current, close circuits to
sounders I at their back points. The main battery M, B, is shown with zinc
to line.
To reverse the polarity of the constant line current without changing its strength,
there is provided at each terminal and way station, a battery L, B, which has
twice the number of cells of the main battery, and which is thrown into circuit
reverse to and opposing the main battery.
t
The line passes through a circuit preserving lever E, and spring a carried
thereby on a block of insulation, which spring closes circuit normally as usual by
making contact with the hook end 1 of lever, and the local battery is located
between the line connection of lever E and the contact b. The lever E is worked
by a magnet F controlled by a key G and local battery v. Normally the
battery L, B, at each station is out of circuit as shown in the drawing. By closing
key G, magnet F moves lever E forward until spring a strikes contact 6 and is
forced away from the hook end 1 of the lever E. This throws the battery L, B,
into circuit with carbon to line over-coming main battery M, B, and producing
a current on line equal to the normal current of M, B, but of opposite polarity.
The polarized relays K which respond to this change in polarity of current close
circuits to sounders M at their back points.

page_text: Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I'declare that what
I claim is :-
1st In a system of Morse telegraphy, the combination with a telegraph line, of
terminal and way stations, a main line battery constantly in circuit, a local
battery at each station having double the power of the main battery, the said local
battery being normally out of circuit, and a key for each of such local batteries
throwing the local battery into circuit reverse to the main battery, whereby the
line current can be reversed at a terminal or way station without changing its
strength, substantially as herein before described.
2nd In a system of Morse telegraphy, the combination with a telegraph line, of
a main line battery constantly in circuit, two or more stations each provided with
a local battery, of double the power of the main battery, normally out of circuit, a
key at each station throwing the local battery into and out of circuit reverse to
the main battery, thus reversing the line current without changing its strength,
a key at each station varying the strength of the line current without regard to
its polarity, and polarized and non-polarized relays, substantially as hereinbefore
described.