IMPROVEMENTS IN ELECTRIC TELEGRAPHS
Year: 1881

page_text: LETTERS PATENT to Alexander Muirhead, of 27, Regency Street, in the City
of Westminster, and Henry Alfred Charles Saunders, of 66, Old Broad Street,
in the City of London, for an Invention of "IMPROVEMENTS IN ELECTRIC
TELEGRAPHS."
PROVISIONAL SPECIFICATION left by the said Alexander Muirhead and
Henry Alfred Charles Saunders at the Office of the Commissioners of Patents
on the 13th April 1881.
ALEXANDER MUIRHEAD, of 27, Regency Street, in the City of Westminster, and
HENRY ALFRED CHARLES SAUNDERS, of 66, Old Broad Street, in the City of
London. "IMPROVEMENTS IN ELECTRIC TELEGRAPHS."
The object of our Invention is to facilitate the reception and retransmission of
messages on long submarine cable-circuits. We employ a double telephonic
repeater in connection with the suspended coil or magnet of the receiving
instruments, and we introduce between one cable and another automatic translating
apparatus operating by light or radiant energy.
The double telephonic repeater which we employ consists of three independent
coils. The middle one is suspended and moveable between the other two." It is
connected to the moveable coil or magnet of a recorder and therefore responds to
the fluctuations of the cable-current in the latter. The other two coils of the
series are fixed and connected with two separate telephones.
A rapid series of currents from a battery is caused to pass through the suspended
coil by means of a tuning fork or other make and break arrangement. Sound will
be produced in the telephones varying in intensity with the proximity of the
suspended coil to the fixed coils.
The nearer the suspended coil to either fixed coil the louder will be the sound in
the corresponding telephone.
For automatic translation between submarine cables we employ an arrangement
which converts radiant energy into electricity.
We use a series of selenium cells extending like the scale of a reflecting
galvanometer, and we so arrange matters that the moveable index of the receiving
Price 6d1

page_text: instrument controls a beam of light or heat and by its motion determines the
number of selenium cells affected by the beam. An electromotive force is thus
created in the band of cells which will be proportional to the amount of movement
of the index.
We employ two relays which we place in closed circuit with the series of the
selenium cells in the following manner :-
One terminal of each relay is connected to the one end of the series of selenium
cells, and the other terminal is connected to the middle of the series of cells.
The relays close their local circuits during the rise in potential of the current
they receive from the selenium cells and open the circuit as the potential falls.
In the local circuits of these relays are placed electro magnets and batteries
which actuate translating levers in connection with the cable..
When the rate of signalling is such that the minor signals tend to run together
we reproduce them automatically in retransmission by mechanism which introduces
a break into the outgoing current and discharges the cable after a definite interval
independently of the operation of the relay.

page_text: the suspended con or magnet of the receiving instruments,
and we introduce between one cable and another automatic translating apparatus
operating by light or radiant energy.
TELEPHONIC RECEIVING APPARATUS.
The double telephonic repeater which we employ consists of three independent
coils A, B, and C, as sketched in plan in Figure 1. The middle one B is suspended
and moveable between the other two A and C. It is connected to the moveable
coil R of a Thomson's recorder and therefore responds to the fluctuations of the
cable current in the latter. The other two coils A and C of the series are fixed
and connected with two separate telephones T1 and T2. A rapid series of currents
from a battery E is caused to pass through the suspended coil by means of a tuning
fork F or other make and break arrangement. Sound will be produced in the
telephones varying in intensity with the proximity of the suspended coil to the
fixed coils. The nearer the suspended coil to either fixed coil the louder. will be
the sound in the corresponding telephone.
The operator placing a telephone to each ear reads by sound the message
transmitted.
For the sake of lightness we construct the suspended coil B of aluminium wire.
Sometimes we modify the arrangement slightly and make use of a single telephone
placed in circuit with the suspended coil. In this case we pass currents from two
separate tuning forks of different pitch through the two outer coils.
Figure 2 illustrates this method, F' and F2 being the two tuning forks in
connection with the coils A and C respectively, and with separate batteries E¹
and E2. T is the telephone in circuit with the coil B.
The motions of the recorder coil R being repeated by the suspended coil B give
rise in the telephone to corresponding variations in the intensity of the two
separate notes.
In Figure 3 is shown another disposition of the three coils A, B, and C, in which
the coil B is suspended so as to move in front of the two outer and fixed coils A
and C. In order more effectively to stop all electro magnetic induction between
the coil B and the coils A and C when the former is at rest or in the zero position,
a thick mass of copper or other good conductor D is placed between the coils A
and C, and slightly overlapping them. The coil B may either be supported at the
end of a light aluminium arm G, as shown in Figure 3, or it may be doubly sus-
pended unifilarly, and connected to the recorder coil R by levers and cords as in a
Thomson's siphon recorder. It is possible also to eliminate the coil B altogether,
and place the two coils A and C close to the recorder coil itself, one on each side of
it, as shown in Figure 4. In this arrangement the tuning fork make and break is
connected up in circuit with the primary P of an induction coil, the secondary
being connected to two terminals of the recorder coil, Vibratory currents are thus
set up in the recorder coil and sounds are produced in the telephones T and T³,
varying in intensity according to the amount of deflection of the recorder coil by
he cable currents.

page_text: AUTOMATIC TRANSLATION.
For automatic translation between submarine cables we employ an arrangement
in which an electrical circuit is affected by radiant energy. We make use of
selenium (or other substance whose electrical resistance is affected by radiant
energy) extended into a band, like the scale of a reflecting galvanometer, and we
so arrange matters that the moveable index of the receiving instrument controls a
beam of light or heat, and by its motion determining the extent to which the
selenium is affected by the beam. Variation of electromotive force proportional to
the amount of movement of the index is thus brought about in a circuit in which a
relay is included.
We employ two relays of the Brown and Allan type, i.e., relays in which the
'contact maker moves with the first rise and the first fall of potential. These
relays we place in close circuit with the selenium in the following manner:-
One terminal of each relay is connected to the ends of the selenium, and the
other terminals are connected to the middle.
In the local circuits of these relays are placed electromagnets and batteries.
The contacts made by the relays we employ actuate translating levers in
'connection with the cable.
Figure 5 is a sketch of the above arrangement of selenium cells, batteries, and
relays; X and Y are the two selenium cells placed in series; R1 and R2, the two
relays of the Brown and Allan type. Two terminals of the relays are joined
together, and to the centre O, of the band of selenium X, O, Y; the terminals X
and Y of the selenium band are connected respectively to one pole of each of the
batteries B1 and B2, and thence to the other terminals of the relays R¹ and R².
M is a mirror galvanometer which, as the receiving instrument of a cable line
directs its beam of light on to the selenium.
Figure 6 shows the modification of the above arrangement, which we make in
order to obviate difficulty arising from the shifting of the zero of the receiving
instrument caused by earth currents.
The band of selenium X, O, Y, is joined up with two coils of wire 61, 62, so as to
form the four members of a Wheatstone's bridge, the battery B being placed
between the centre O of the band and Z, and the two relays R' and R2 between
the terminals X and Y of the band. With this arrangement of the different
parts it is immaterial whether when no signals are passing the beam is or is not
reflected exactly on the centre O of the band.
Figure 7 shows another modification in which the two relays R' and R² are
placed in the secondary circuit of an induction coil P, S, the primary of which is
connected to the terminals X and Y of the selenium band. The relays are by
this means caused to respond more promptly to changes in the resistance of the
selenium band X, O, Y.
it.
Figure 5a is a sketch to illustrate the construction of the framework of the
selenium band X, O, Y. x, o, y, are three combs of copper or brass, o being a double
one. They are fixed with their teeth interlacing to a plate of slate or ebonite.
The interstices between the teeth of these combs are filled with selenium (freed
from sulphur and other impurities) in the usual way, and carefully annealed. Over
the band X, O, Y, of selenium is placed a cover W having triangular holes cut in
This band of selenium is placed so that the beam from a strong source of light
L is reflected from the mirror on to the zero line O when there is no current
flowing through the galvanometer M. or receiving instrument. Movement of the
beam to one side or the other of O causes more of the selenium to be exposed to
its influence, and so alters the resistance of the selenium in proportion to the
amount of deflection of the beam and a corresponding alteration in the strength
of the current flowing through one relay or the other takes place. The relays
being constructed on the Brown and Allan principle, with the moveable zero
arrangement respond to every variation of the current flowing through them. By

page_text: substituting in place of the relays R1 and R2, in Figure 5, the two telephones T¹
and T2, of Figure 4, an arrangement is made whereby, with an intermittent beam
of light, the motions of the mirror reflecting the beam are indicated by sounds in
the two telephones of varying intensity. Or Bain's chemical recorder may be
included in these circuits.
We apply the arrangements just described in connection with a translator so
contrived that when the rate of signalling is such that the minor signals tend to
run together they are reproduced automatically in retransmission by mechanism
which introduces a break into the outgoing current, and discharges the cable after
a definite interval independently of the operation of the relay.
Figure 8 is a plan; Figure 9 is a side elevation, and Figure 10 is an end view of
the translator.
To Figure 8 there is added a diagramatic view of the selenium band, the relays
and parts connected therewith.
The translator consists of the levers A and A', which are both connected to the
line to which the signals are to be translated.
The blocks C and Z are connected to the poles of the translating battery B, the
centre of which is connected to earth.
The springs a, a, and a¹, a¹, are for prolonging and making the contacts more
perfect, and are adjusted by the screws b, b¹, and 61, 6111
The bridge D is for carrying the upper contacts & and d' and the spring S,
which is connected to earth and insulated from the bridge D by the piece of
vulcanite V.
The levers A and A¹ are actuated by the electromagnets E and E¹, and for
ordinary translation are connected directly in the local circuits of the relays R¹
and R2
When the translator is at rest the levers A and A' are made to press against the
contacts & and d' by means of the spiral springs S, P. The lever A presses the
spring S and the spring a¹ which is above it against the contact d, but A is insulated
from the spring S by an insulating stud e.
The contact piece i of lever A³ passes through a hole in the spring S, and makes
the contact with the screw d', and in this position the cable is put to earth by
means of the springs a¹, a³, and S.
Upon a current passing through the relay R¹, the local circuit of that relay is
completed through the electro-magnet E, and the lever A is drawn down upon the
spring contact of the lower contact block C. This movement breaks the earth
connection as the spring S follows the lever and leaves the spring a¹, and puts the
copper current from the translating battery B to line.
On a current passing through the relay R2, the lever A' is drawn down, breaking
the earth contact from the spring a¹, and making connection with the block Z, thus
putting the zinc current from the translating battery B to line.
It will be seen that the cable is only to earth when the levers A and A' are both
at rest on their upper contacts d and d².
To introduce when necessary a break into the outgoing current from the
translating battery, and discharge the cable after a definite interval independently
of the operation of the relays R' and R2, two rocking pieces T and T are employed;
they are actuated respectively by the levers A and A¹, and work between adjustable
screws ff. To these contact pieces springs g and gl are attached, making
connection with the screws h, h¹.
Between the rocking pieces T, T¹, and the screws h, h¹, are connected the
electro-magnets E, E', the local batteries B', B¹¹, and the tongues and contacts of
the relays R¹ and R².
The local circuits by these means of the relays R₁ and R² are made and broken
at a rate depending upon the rate of oscillation of the levers A and A¹.
To the levers A and A¹ are attached long and somewhat flexible rods with
sliding weights W, W, after the manner of a pendulum. The periods of vibration

page_text: of A, A¹, are regulated by the distance of these weights from the centre of
oscillation o.
The time of oscillation may also be controlled by fluid resistance either in the
shape of a "dash pot" or fans working in fluid attached to the levers.
Having thus described the nature of our said Invention, and the manner of
performing the same, we would have it understood that we claim,―
First. The combination of telephonic repeaters with receiving instruments,
substantially as above described.
Second. The combination of a receiving instrument directing a beam of light or
radiant energy and a material such as selenium of variable conductivity under the
influence of radiant energy to translate the received signals into another circuit or
circuits, substantially as described.
Third. The combination in a translating apparatus of selenium or like material
relays and translators, substantially as described.
Fourth. The means for automatically introducing breaks into the outgoing
signals of translating apparatus, substantially as described.
Fifth. The translator or automatic retransmitter, substantially as described.
In witness whereof, I, the said Henry Alfred Charles Saunders, have hereunto
set my hand and seal, this Eleventh day of October, in the year of our
Lord One thousand eight hundred and eighty one.
HENRY ALFRED CHARLES SAUNDERS. (L.S.)