IMPROVEMENTS IN THE MEANS FOR COMMUNICATING INTELLIGENCE BY ELECTRICITY, AND IN TELEGRAPHY BY INDUCED CURRENTS
Year: 1880

page_text: LETTERS PATENT to Herbert John Haddan, of the Firm of Herbert and
Company, Solicitors of ats, of 67, Strand, in the City of Westminster,
Civil Engineer, for an ention of "IMPROVEMENTS IN THE MEANS FOR
COMMUNICATING INTELLIGENCE BY ELECTRICITY, AND IN TELEGRAPHY BY
INDUCED CURRENTS." A communication from abroad by Samuel Latham
Mitchell Barlow, of New York, in the State of New York, United States of
America, Counsellor at Law, Assignee of the Inventor, Dr. Orazio Lugo, of the
same Place.
COMPLETE SPECIFICATION filed by the said Herbert John Haddan at the
Office of the Commissioners of Patents on the 7th December 1880.
•
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Solicitors of
Patents, of 67, Strand, in the City of Westminster, Civil Engineer. "IMPROVEMENTS
IN THE MEANS FOR COMMUNICATING INTELLIGENCE BY ELECTRICITY, AND IN
TELEGRAPHY BY INDUCED CURRENTS.". A communication from abroad by Samuel
Latham Mitchell Barlow, of New York, in the State of New York, United States
of America, Counsellor at Law, Assignee of the Inventor, Dr. Orazio Lugo, of the
same Place.
The object of my Invention, speaking generally, is to produce intelligible signals
in a long telegraphic circuit with great distinctness by means of secondary induced
currents or pulsations of high electro-motive force or intensity, which are generated
by means of a battery or batteries of comparatively small power through the
medium of induction coils.
This Invention, broadly stated, consists in a novel art, method, or system of
producing intelligible signals at a distant station in an electric circuit by making
and breaking at the transmitting station an electric current in the primary wire of
induction coil, constituting a transmitting or generating circuit of very low
resistance, thus producing corresponding electric currents of very high tension in
the secondary wire of said induction coil which constitutes part of the line wire,
and transmitting said current through the secondary wire of a corresponding
receiving induction coil, also of very high resistance, and included in the line wire,
which operation induces corresponding currents of low intensity in the primary
circuit of said receiving induction coil, in which primary circuit a helix of low

page_text: :'
resistance actuating a diaphragm or plate sounder is included, and which primary
circuit is again of very low resistance.
The interrupted currents thus produced in the primary wire of the receiving
induction coil correspond exactly with those produced in the primary wire of the
transmitter, and by a proper receiving instrument are converted into intelligible
signals (as by a sounder).
An important fact upon which is based one modification of this Invention is the
following: When an electrical pulsation or current of brief duration is produced
in the secondary circuit of an ordinary induction coil, upon the closing of the
primary circuit the induced current is of opposite polarity or direction to the
inducing current, and another pulsation is produced at the moment of breaking
the primary circuit, but in this case its polarity or direction is the same as that of
the primary current.
Another important consideration is as follows:-The electro motive force or
intensity of the secondary current may be made greater than that of the primary by
increasing the number of convolutions of wire in the secondary wire of the induction
coil in proportion to the number of convolutions of the primary, but whatever this
proportion may be, it is well known that the electro motive force or intensity of
the secondary pulsation which takes place when the primary circuit is closed is very
much less than that of the pulsation which occurs when the primary circuit is
broken. Hence a difficulty has arisen in the application of this apparatus to
telegraphy, especially upon circuits of great length. The signals being made at the
sending station by simply opening and closing the primary circuit of the induction
coil, depending upon the alternate secondary pulsations thus produced to operate
the receiving instrument at the distant station, it has been found in practice that
the comparatively feeble pulsations occasioned by the closing of the primary circuit
often failed to produce any effect upon the receiving instrument, while at the same
time the pulsations caused by the breaking of the primary circuit were perfectly
responded to by the receiving instrument.
This Invention operating on the principle first above stated by me is intended to
overcome the difficulties I have enumerated; I can by means of it produce all the
secondary pulsations which are employed in the formation of signals, by the
breaking or interruption of the primary circuit, and utilize the feebler pulsations
caused by the closing of the primary circuit for the purpose of clearing the line
from static electricity between the signals. This is very important in the operation
of long lines, and especially of cables, when the signals are required to be sent in
rapid succession.
I have found the best results to be produced by having a very wide working
margin between the primary and secondary coils, that is to say, having a primary
circuit of very low resistance, and a secondary coil of comparatively very high
resistance; for instance, as an example, I have used with great advantage a line wire
having a resistance of 16,000 ohms, primary coils with a resistance varying from
two tenths of an ohm to one ohm, and secondary coils with a resistance varying
from 12,000 to 4000 ohms.
I have discovered that by the means above recited I can dispense with insulation
of the line wire, even if it passes through considerable bodies of water, and that an
earth or metallic circuit may also be often dispensed with.
The accompanying Drawing is a diagram illustrating this Invention, and
represents two terminal stations connected by a line; the apparatus at the two
stations is the same, and therefore description of one will suffice for both.
In the Figure 1 is an induction apparatus of well known construction, consisting
of an iron core c, upon which is wound a primary coil p of comparatively small
number of convolutions of coarse wire, and outside of this a secondary coil 8, having
a much larger number of convolutions of finer wire; at Ris a receiving instrument,
which for some purposes may be of the ordinary construction, consisting of an
electro-magnet, having an armature arranged to vibrate between adjustable stops
and a retracting spring, all of which are well known, and therefore need no detailed

page_text: description or representation by Drawings, but the receiving instrument which I
find most efficient consists of a sounder, shown at T, which although resembling an
ordinary magneto telephone in appearance, differs essentially from it in the fact
that it is not necessarily a reproducer of sound, that is, a silent electric signal.at
the transmitting station will produce sound at a receiving station.
The induced current of electricity of very high tension coming from the secondary
wire of the induction coil at the transmitting station is conveyed to the secondary
wire of the induction coil at the receiving station, and there induced inversely
through such secondary wire into the primary wire of said induction coil (which
primary wire or circuit is of very low resistance), and passing through the helix of
the sounder, which is in circuit with said primary wire, causes a metal dial or
plate in the receiving instrument to vibrate and thus give an audible sound.
This plate constitutes a sounder, and may be greatly varied in thickness and
tension. I prefer to use a diaphragm or plate, as it can be thrown into vibration
with very small expenditure of electro motive force. In order to obtain the best
result, the helix of the sounder should have a very low resistance, equal to that of
A sounder may also, if
the primary wire of the receiving induction coil.
desired, be connected with the secondary wires of the receiving induction coil.
One terminal of the secondary coils of the induction apparatus may be connected
with the earth at 1, but I have discovered that it is not necessary, and the other by
the wire 2 with the receiving instrument, whence the wire 3 goes to the line and
distant station.
By means of a switch c the line may be connected directly from the receiving
instrument to the earth in receiving communications, thereby removing the
resistance. of the secondary coils s from the circuit if desired, or it may be discon-
nected entirely from earth connections by the same switch.
The form of transmitting instrument which I prefer is as follows:-The trans-
mitting key K oscillates between four stops or contacts b, b', i, i'. The stops band 6'
are respectively connected with the like poles of the local batteries B and B', which
may have from one to, say, five cells each.
The remaining poles of these batteries are joined by a common wired to one
terminal of the primary coil c of the induction apparatus, and the other terminal
of the batteries connected by a common wire e with the contacts i, ', of the
key K.
When the key is at rest, as shown in the Figure, it forms a connection between
the contacts b and i, and thus closes the circuit of, the battery B through the
primary coil p of the induction apparatus, thus causing the core c to become
magnetic.
If now the key K be depressed the primary circuit is momentarily broken, which
demagnetizes the corce c and induces a pulsation of great intensity in the secondary
coil 8, which traverses the line and causes the receiving instrument R to produce an
intelligible signal on the sounder, or to momentarily. attract its armature and
produce a signal.
The key then closes the circuit of battery B₁ between the points b¹ and i¹, which
5 transmits a feebler pulsation of reverse polarity; this serves to discharge the
line or cable of any static electricity remaining after, the transmission. of the
signal.
When the key is raised the primary circuit is again broken between b' and ',
and another pulsation is transmitted having the same polarity as the one which was
transmitted by depressing the key, and this is again followed by a weak pulsation
of opposite polarity, as before.
Thus a pulsation of the same polarity, is produced by breaking the primary
circuit at each elevation as well as each depression of the key.
If the key is manipulated in the ordinary, manner, as in Morse's telegraph, the
5 signals upon the receiving instrument, when the armature is used and not the
sounder, will consist of a series of dots, as they are technically termed, and the
different letters or characters may be distinguished by means of the varying intervals

page_text: of time between them if read by sound, or by varying intervals of space when
recorded on paper in the ordinary manner.
If an armature with a retracting spring is being used, by making the local
battery B¹ somewhat more powerful than the battery B a corresponding difference
will be manifested in the respective signals upon the receiving instrument, and
they can then be read as from a common Morse sounder.
The receiving instrument may be constructed as a direct sounder or recorder, or
as a relay, to work other instruments through the agency of a local battery.
Way stations may be inserted at any point between the terminal stations in a
manner well understood, the line being continuously connected at each of such
stations with the secondary wire of the induction coil, and by an arrangement of
apparatus similar to that shown and described at the terminal station messages
may be sent to and taken from the primary wires of the induction coils at any or
all of such intermediate stations. By the use of this Invention intelligible tele-
graphic signals may be transmitted through several hundred miles line by means
of power derived from a battery of two or three ordinary cells, and the annoyance
and expense inseparable from the use of powerful batteries of two or three hundred
cells is entirely avoided.
By the use of secondary currents of very high tension, as above described,
intelligible signals may be transmitted without any insulation on the line wire,
thus saving very large expense.
I do not desire to confine myself to the particular construction and arrangement
of the transmitting key which I have described, or to the production of successive
currents of opposite polarity, though this is the best mode of using the secondary
1. The herein before described novel art, method of, system of producing intelli-
gible electric signals in an electric circuit, which consists in causing signals to be
made by makes and breaks of the electric current in the primary wire of an
induction coil at the transmitting station, which primary wire or circuit is of low
resistance, thereby inducing corresponding currents in the secondary wire of said
induction coil in the line wire and in the helix of the receiving apparatus, the line
wire having no return circuit or earth connection.
2. The hereinbefore described novel art, method, or system of transmitting
intelligible electric signals in an electric circuit by causing makes and breaks in
the primary circuit of an induction coil, which makes and breaks are reproduced
upon a suitable receiver in the secondary circuit, including a line wire
uninsulated.
3. The combination, substantially as hereinbefore set forth, of the primary wire
of an induction coil, constituting a primary circuit including a battery and a key,
a secondary circuit including a single line wire without earth connections, and a
receiver.
4. The hereinbefore described improvement in the art of producing intelligible
signals at a distance in an electric circuit, which improvement consists in causing
signals to be made by makes and breaks of the electric current in the primary wire
of an induction coil at the transmitting station (which primary wire or circuit is
of very low resistance and constitutes a metallic circuit), thereby inducing corre-
sponding currents, but of very high tension, in the secondary wires of said induction
coil, in the line wire, and in the secondary wire of a corresponding induction coil
of high resistance at the receiving station, the currents of which wires act inversely
by induction upon the primary wire of the receiving induction coil (which primary
is of very low resistance) and a helix, also of low intensity, actuating a diaphragm
or plate sounder included in said primary wire, which constitutes a metallic
circuit.
5. The combination, substantially as herein set forth, of the primary wire of an

page_text: induction coil, constituting a metallic circuit of very low resistance, the battery,
the key, and the helix actuating the diaphragm or plate sounder included in a
branch of said primary circuit, whereby the key and battery are both cut out of
circuit by opening the key.
6. The combination, substantially as herein set forth, of the battery and the key
in the primary wire of an induction coil at the transmitting station (said primary
wire constituting a circuit of very low resistance), the secondary wire of said
induction coil, the secondary wire of the receiving induction coil (both secondary
coils being of very high resistance), the line wire connecting said secondary wires,
and the helix actuating the diaphragm or plate sounder included in a branch of
the primary wire of the receiving induction coil, constituting a metallic circuit of
very low resistance, whereby the key and battery are both cut out of circuit by
opening the key.
7. The combination, substantially as herein set forth, at each station of the
primary and secondary wires of an induction coil, a battery, and a key in one
branch of the primary circuit or wire, and a helix of low resistance actuating a
diaphragm or plate sounder included in another branch of said primary circuit,
with a line wire connecting the secondary wires of the respective induction coils,
each primary circuit being of very low resistance and having the capacity of
cutting out its battery and key, and each secondary of comparatively very high
resistance.
8. The hereinbefore described art, method, or system of transmitting telegraphic
signals by secondary or induced currents, which consists in producing the pulsations
constituting the signals by the breaking of the primary current, and in employing
the weaker pulsations caused by closing the primary circuit to clear the line from
static electricity betweeen the signals.
9. The combination, substantially as hereinbefore set forth, of an induction
consisting of an iron core, a primary and a secondary coil, a key or transmitting
instrument, which momentarily interrupts the circuit of the primary coil, both
when it is depressed and when it is elevated, and a receiving instrument included
in either one of the circuits of the induction coil at the receiving station.
10. The combination, substantially as bereinbefore described, of an inductor
consisting of an iron core, a primary and a secondary coil, and a key or transmitting
instrument, which momentarily interrupts the circuit of the primary coil, both
when it is depressed and when it is elevated.
In witness whereof I, the said Herbert John Haddan, have hereunto set my
hand and seal, this Sixth day of December 1880.
H. J. HADDAN. (L.S.)