IMPROVEMENTS IN ELECTRIC TELEGRAPHS
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by William Chase Barney at the Office
of the Commissioners of Patents on the 11th September 1879.
WILLIAM CHASE BARNEY, of the City and State of New York, United States
of America, now of 8, Southampton Buildings, London. " IMPROVEMENTS IN
ELECTRIC TELEGRAPHS."
This Invention has for its object to increase the rapidity with which messages
may be transmitted through long lines of electric telegraphs, and more especially
through submerged cables and subterranean lines.
It is a well established fact that the speed of electric transmissions through
submarine cables depends on the electrical condition of the cable.
It is also well established that the maximum speed of transmission of electric
signals is obtained when the duration of the discharge of the cable is not longer
than that of the charge.
The laws of electric currents applicable to air lines, are also applicable to
submarine cables; but in consequence of the induction which is produced in these
latter, the duration of the variable period of the electric propagation is much longer
than in air lines.
The difficulties which present themselves in submarine cables are, 1st., the
induction produced during the propagation of the electric current; 2nd., the
slowness of the discharge; 3rd., the secondary discharges due to the condensation.
It is well established that, 1st., the phenomena of induction produced in
submarine cables take place only during the propagation of the electric currents.;
2nd., the induction is in proportion to the tension of the source of electricity; 3rd.,
the variable state of the current is independent of the tension of the source of
electricity; 4th the condensation which takes place in a submarine cable when the
conductor is insulated is much greater than when it is in communication with the
earth.
My Invention presents a new combination of various devices proved by long
practical use to be efficacious to diminish the induction, and thereby to increase
the speed of the propagation of the electric current; and also to diminish the
duration of discharge; and also to avoid the effects of the secondary discharges on
the receiving instument
In order to diminish the induction, 1st., I use a current of low tension; 2nd., I
work under the influence of a current taken at an epoch more or less of its variable

page_text: state; 3rd., I keep the cable always in communication with the earth near to both
ends.
In order to diminish the duration of discharge I arrange that a current of the
opposite kind of electricity to that of the charge passes into the cable from each
end of it at the moment the cable is separated from the battery of charge; the
effect of these two currents last sent into the cable is to restore the cable to a
neutral state in a duration of time not longer than that of the charge.
In order to avoid the effects of the secondary discharges on the receiving
instrument I place this instrument in an independent circuit through which the
secondary discharges cannot pass.
When a submarine cable, after having received a charge of electricity, is
suddenly separated from the battery and is put in communication with the earth
simultaneously at both ends, the duration of the discharge is about equal to that
of the maximum charge; that is, to the duration of the contact of the cable with
the battery necessary for the electric current to attain in the cable its maximum
intensity. The equality of duration of charge and of discharge will not exist when
the intensity of the current in the cable is allowed to attain only a fraction of its
maximum intensity by diminishing the durations of contact of the cable with
the battery, because the force which furnished the charge is much less than the full
force of the battery, hence the charge of the cable is made under the influence of an
increasing tension, but the discharge is always effected under the same conditions,
that is, under the influence of a force the tension of which is constantly decreasing,
and the duration of discharge remains the same as when the charge in the cable has
attained its maximum intensity.
In order therefore to increase the speed of transmission beyond that obtainable
when the current has attained its maximum intensity in the cable, it is necessary
to reduce not only the duration of charge, but also that of discharge.
The duration of charge and of discharge can be made equal in all cases by
using currents of an opposite kind of electricity to neutralize the previous charge.
In case the neutralizing current be sent into the same end only of the cable, into
which the previous current was sent, the greater part of the previous current will
continue to flow to the receiving end, and will produce a prolonged action on the
receiving instrument.
When a cable, one end of which is in communication with the earth, is suddenly
separated from the battery at the other end, and is put in communication with the
earth, the charge in the cable divides itself at the centre of resistance of the circuit
into two currents of discharge, and the charge in the parts of the cable on the side
of the centre of resistance next to the sending end will flow back and pass to the
earth, and the charge in the cable on the other side of the centre of resistance will
continue its course towards the other end and flow to the earth, producing a 4
prolonged action on the receiver.
Referring to the accompanying Drawing, -
In my system the cable always being to earth at the receiving end, the division
of the current of charge into two currents of discharge is effected by the cable
being put to earth at the sending station by the action of the lever-key L, which
separates the cable from the battery of charge, and instantly makes a contact on
the small lever l, which is in communication with the earth.
The discharge of the cable, or in other terms, the restoration of the cable to a
neutral state is produced by sending into the cable at both ends simultaneously
a current of an opposite kind of electricity to that of the previous charge. This is 5
effected by the action of the lever-key L, which on being depressed separates the
cable from the earth and instantly puts it in communication with the zinc pole
of a battery B, from which battery a current of electricity enters the cable and
neutralizes the return current of the opposite kind, and that part of the cable on
the near side of the centre of resistance is restored to a neutral state in a duration 5
of time not longer than that of the previous charge, which the cable had received
from battery A when the key L was on the back anvil. At this same moment

page_text: the current from the zinc pole of battery C neutralizes the charge of the opposite
kind of electricity, flowing with a constantly decreasing tension from the centre of
resistance. The action of these two currents of negative electricity on the previous
charge of positive electricity in the cable produces in the cable, each one on its own
side of the centre of resistance, the same neutralizing effect as though the cable
were severed at the centre of resistance, and those ends insulated, and thus the two
portions of the cable on each side of the centre of resistance are restored to a
neutral state in the same manner as if the two portions were separate cables,
and the entire cable is thus placed in the best condition for the propagation of
the positive current to be sent from battery A to make another signal.
In case the charge sent into the cable from the sending station to neutralize the
previous charge is more than is necessary to neutralize the return current, the
excess will flow back to the earth at the instant the cable is separated from the
battery B, and is put in communication with the earth, which is effected by the
lever-key L making contact on the small lever C on its return to contact on back
anvil k. This negative current sent into the cable to neutralize the return current
is furnished by a special battery B composed of fewer cells than battery A, and is
connected for quantity for the reason that the return current is rather of the nature
of quantity than of intensity.
When several conductors are connected to the pole of a battery the current from
the battery will be divided among the several conductors, and its intensity in each
conductor will be in inverse proportion to their respective resistances.
I use this principle for the purpose of regulating the intensity of the current of
battery C in the conductor a in the following manner :-A rheostat R³ is placed on
the line, which connects line a with the earth, and the resistance in the rheostat
is first adjusted so that the current of battery C which passes into line a shall be
just sufficiently strong to annul the action of battery D and no stronger; the
resistance in the rheostat R is then gradually reduced until battery D will act and
the current from it will pass on one side through the rheostat R³ to earth, and on
the other side through the receiving instrument to earth.
The intensity of the current of battery C can be adjusted by means of the
rheostat R5, so that a very slight increase of it by the current of battery A
will suffice to annul the action of battery D. The current of battery C in the
conductor a acts like a relay to open and close the circuit of battery D, and its
action is direct and is more reliable and more easily adjusted than the most delicate
relay, and it has the great advantage of being free from magnetic influences,
inseparable attendants upon all relays.
When battery A is put in communication with the cable the current from it
reinforces the current of battery C in the line a and annuls the action of battery D,
and no current passes through the receiving instrument; and when battery A is
separated from the cable the intensity of the current of battery C in the line a
becomes less, and battery D acts instantaneously on the receiving instrument, and
the signals recorded will be distinct and square-ended without tailing, because
battery D begins to act abruptly with its full force and ceases abruptly without
attenuation.
The changes of intensity of the current from battery C in the line a takes place
in the minimum time because the cable is in the best condition for the propagation
of the current of battery A.
The condensation which takes place in a cable when insulated is much greater
than when the cable is in communication with the earth, the difference is about
double; in my system the cable is always in communication with the earth through
the rheostats R2, R3, and R³, and thereby the condensation is greatly diminished.
The annexed diagram shows the combination of batteries and circuits with the
cable. I do not confine myself to the use of the lever-key here represented; any
instrument may be used which will put the cable in communication with the
batteries and earth in the manner described.
At the transmitting station, when a lever-key as represented in the diagram is

page_text: used, the end of the cable is connected to the lever which is insulated from the
other parts of the instrument, and this lever when at rest is kept in contact with
the back anvil k, and this anvil is connected to the copper pole of a battery A by a
conductor in which is placed a rheostat R¹; the front anvil p is connected to the
zinc pole of a battery B which is connected for quantity; the two other poles of
these two other batteries are connected to the earth; the small lever upon which
the lever-key L makes contact on its movements between its contacts on the
anvils and p is connected with the earth by line d, and the cable near to its
junction with the lever-key L is always in communication with the earth through
a rheostat Rs (Figure 1).
At the receiving station the end of the cable is connected to the zinc pole of a
battery C, the copper pole of which is connected by a conductor a to the copper
pole of a battery D; and the zinc pole of this battery is connected through a
rheostat R* to a receiving intrument P, the other side of which is connected to the
earth. The conductor a is connected to the earth by line f on which is placed a
rheostat Rs, and the cable near to its junction with zinc pole of battery C is
connected to the earth by a conductor 9 on which is placed a rheostat R³
(Figure 2).
On long cables I place a condenser V in the place of rheostat R* (Figure 3).
The rheostat R¹ serves to regulate the intensity of the current of battery A, and
the rheostat R that of battery D.
In order to effect the contacts of the cable with the batteries and earth necessary
for a speed of transmission greater than thirty words a minute, which is about the
maximum obtainable by an experienced operator with any of the lever-key circuit
closers, I use an automatic transmitter with perforated paper. The action of an
automatic transmitter is more prompt and more regular, and the speed of trans-
mission is easily regulated.
In the band of paper are perforated by a machine three parallel lines of holes,
grouped so as to reproduce on the receiving paper the usual telegraphic characters.
Through the holes on one of the lines the cable is put in communication with the
copper pole of a battery A, through the holes on another line with the earth, and
through the holes of a third line with the zinc pole of battery B, in the manner and
order as required by my Specification.
I prefer to use the "bain" receiver, with paper saturated with a special solution of
iodide of potassium, which ensures the permanency of the marks on the paper. It is
well known that the "bain" chemical system gives a perfect record of the signals at a
much greater speed of transmission than any other system. Iodide of potassium is
extremely sensitive to the decomposing action of an electric current; so sensitive is
it, that with a battery of three "Leclanché" cells, medium size, I have recorded in one
minute 200 words through a resistance of 5111 ohms, and with ten similar cells
518 words in one minute through 10,000 ohms resistance; the marks on the paper
were in the usual telegraphic alphabet on one straight line, of a deep brown colour,
square-ended and not tailing.
The perforator is very simple in its construction, prompt and sure in its action,
making each letter and proper space by one movement of a lever, and can be
operated by any person familiar with the English alphabet, and the transmitting
and receiving machines can be superintended by a telegraph clerk of ordinary
ability.
In Figure 4 are shewn the connections of the three styles with the batteries and
earth, also the perforated paper; and also the signals as marked on the chemically
prepared paper.
The transmission of signals is made in the following manner, to clearly
elucidate which, I represent a lever-key L in the Figure 1, without confining myself
to this particular kind of instrument.
When the lever-key L is in contact with back anvil the cable receives a charge
of positive electricity from battery A, and this charge passes on to the other end of
the cable and reinforces the current of battery C, and that part of this reinforced

page_text: current, which passes into the conductor a, annuls the action of the battery D, and
consequently no effect is produced on the receiving instrument the other part of
this current passes to the earth through the rheostat Rs. On depressing the lever-
key L the cable is separated from the battery A and is instantly put in communi-
cation with the earth by the contact made by lever-key L on the small lever l, and
the return current begins immediately to discharge itself into the earth; the further
depression of lever-key L separates the cable from the earth, and puts it in
communication with the zinc pole of battery B, from which the negative current
passes into the cable and neutralizes any remains of the return current; when the
lever-key L is allowed to return to make contact on back anvil k, in its passage it
makes contact on small lever 7 by which the cable is put in communication with the
earth, and any excess of charge from battery B beyond what is necessary to
neutralize the return current, will flow back to the earth.
When the cable is separated from battery A and is put to earth, the current of
battery C being no longer reinforced by that of battery A is too weak to arrest the
current of battery D in the line a, and the currents from this battery pass on one
side through rheostat R³ to the earth, and on the other side through the receiving
instrument P to earth, acting thereon in proportion to the duration of the
separations of the cable from battery A, which durations are regulated by the
instrument used for transmission.
The results which necessarily follow the application of the above stated principles
and facts in my combination are,―
First. The duration of the discharge of the cable, or in other terms, its restoration
to a neutral state is not longer than that of the charge, whether the charge has
attained its maximum intensity or only a fraction of it.
Second. The cable is put in the best condition for propagation of the electric
current.
Third. The propagation of the electric current through the cable is made in the
minimum time.
Fourth. The changes of intensity of the current of battery C in the conductor a
are made in the minimum time.
Fifth. The maximum speed of transmission is obtained.