IMPROVEMENTS IN ELECTRIC TELEGRAPHS
Year: 1876

page_text: LETTERS PATENT to Sir James Anderson, Knight, and William Henry Ash,
both of No. 66, Old Broad Street, in the City of London, for the Invention of
"IMPROVEMENTS IN ELECTRIC TELEGRAPHS."
Sealed the 17th March 1876, and dated the 1st January 1876.
PROVISIONAL SPECIFICATION left by the said Sir James Anderson and
William Henry Ash at the Office of the Commissioners of Patents on the 1st
January 1876.
Sir JAMES ANDERSON, Knight, and WILLIAM HENRY ASH, both of No. 66,
Old Broad Street, in the City of London. "IMPROVEMENTS IN ELECTRIC
TELEGRAPHS."
This Invention has for its object improvements in electric telegraphs, and consists,
first, in means whereby two messages can be sent in the same direction at the same
time, a system of working now known as the "multiplex" system; and, second, in
means by which in working cable lines the battery power applied to the cable can
be regulated so that when contact is first made more battery power may be applied
than remains in operation when the contact made by the key is prolonged.
In order to transmit two messages simultaneously in the same direction we
employ two keys so arranged, as is illustrated by the annexed diagram A, that
when both keys are at rest a strong zinc current goes into the line when key No. 1
is depressed; then the zinc current is cut off, and a copper current is transmitted.
When key No. 2 is depressed only a comparatively weak zinc current is sent;
when both keys are depressed no current passes.
The arrangements at the receiving end are illustrated by the diagram B. The
receiving instrument No. 1 is in connection with a relay, which completes a local
circuit when a copper current passes in the line, and also when no current is
passing, and the receiving instrument No. 2 is in connection with two relays. One
of the relays operates only to break the local circuit when the strong zinc current
passes, and the other breaks the circuit whenever the copper current passes. The
tongues of both relays fall to their contact points when no current passes in the
line.
According to another arrangement I so arrange the keys, as is illustrated by the
diagram C, that when the keys are at rest no current passes into the line. When
No. 1 key is pressed down a zinc current passes; when No. 2 key is pressed down

page_text: a copper current passes, and when both keys are down a stronger zinc current enters
the line. In this case the arrangements at the receiving end are such as are
illustrated by the diagram D.
No. 1 receiving instrument works in connection with a relay which completes a
local circuit whenever a zinc current passes.
No. 2 receiving instrument works in connection with two relays, and it is pro-
vided with two coils in separate local circuits.
The relays when at rest operate to short circuit the batteries of the local circuits.
When a copper current passes in the line one of the relays breaks the short circuit,
and allows one of the local batteries to act on the instrument; also when a powerful
zinc current passes the other relay breaks its short circuit, and so causes the
receiving instrument to operate.
The arrangements may be modified so that one key may transmit a copper
current, the other a strong zinc, and both key down simultaneously a weaker zinc,
and so forth. Similarly arrangements may also be made to work with three
strengths of current.
In some cases, in order to prevent breaks in the signals I employ a relay which
maintains the contact whilst the tongue is travelling, and breaks contact only when
it comes against the insulated stop.
We employ a similar contrivance in connection with the transmitting arrange-
ment of cable lines. As is illustrated by the diagram E we cause the depression
of the key to complete a local circuit, in which a relay, such as above described, is
included. Immediately the tongue of the relay leaves its stop it puts the main
battery on to the cable, and it remains on whilst the tongue of the relay is
travelling. As the tongue reaches its further stop the main battery is taken off,
and a second weaker battery is applied, which remains on until the finger key rises.
The finger key in rising breaks the connection between the whole of the sending
battery, and the cable at the same time that it breaks the local circuit, it may also,
as the diagram indicates, make contact for a reversing battery, which is commonly
used in cable telegraphy.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Sir James Anderson and William Henry Ash in the Great Seal Patent
Office on the 1st July 1876.
Sir JAMES ANDERSON, Knight, and WILLIAM HENRY ASH, both of No. 66,
Old Broad Street, in the City of London. " IMPROVEMENTS IN ELECTRIC
TELEGRAPHS."
This Invention has for its object improvements in electric telegraphs, and consists,
first, in means whereby two messages can be sent in the same direction at the same
time, a system of working now known as the "multiplex" system; and, second, in
means by which in working cable lines the battery power applied to the cable can
be regulated so that when contact is first made more battery power may be applied
than remains in operation when the contact made by the key is prolonged.
In order to transmit two messages simultaneously in the same direction we
employ two keys so arranged, as is illustrated by the annexed diagram A, that
when both keys are at rest a strong current, say zinc, goes into the line when key
No. 1 is depressed; then the zinc current is cut off, and a copper current is trans-
mitted. When key No. 2 is depressed only a comparatively weak zinc current is
sent; when both keys are depressed no current passes.
The arrangements at the receiving end are illustrated by the diagram B. The
receiving instrument No. 1 is in connection with a relay, which completes a local
circuit when a copper current passes in the line, and also when no current is
passing; and the receiving instrument No. 2 is in connection with two relays. One
of the relays operates only to break the local circuit when the strong zinc current

page_text: passes, and the other breaks the circuit whenever the copper current passes. The
tongues of both relays fall to their contact points when no current passes in the
line.
According to another arrangement we so arrange the keys, as is illustrated by
the diagram C, that when the keys are at rest no current passes into the line.
When No. 1 key is pressed down a zinc current passes; when No. 2 key is pressed
down a copper current passes, and when both keys are down a stronger zinc current
enters the line. In this case the arrangements at the receiving end are such as are
illustrated by the diagram D.
No. 1 receiving instrument works in connection with a relay, which completes a
local circuit whenever a zinc current passes.
No. 2 receiving instrument works in connection with two relays, and it is pro-
vided with two coils in separate local circuits.
The relays when at rest operate to short circuit the batteries of the local circuits.
When a copper current passes in the line one of the relays breaks the short circuit,
and allows one of the local batteries to act on the instrument; also when a powerful
zinc current passes the other relay breaks its short circuit, and so causes the
receiving instrument to operate.
Diagram E shows a modification admitting of the use of one battery only at the
sending end.
Double contact keys are employed when key No. 1 is up, as it is shown in the
diagram; it presses on a spring which carries two contact pieces, one on the upper
and the other on the under side; they are insulated from each other, and connected
respectively with the zinc and copper poles of the battery. The back contact of
the key puts the zinc pole to the line, whilst by the downward deflection of the
spring carrying the contact pieces the copper pole is put to earth. When the key
is put down both these connections are broken, whilst by a similar arrangement on
the front side of the key the copper pole of the battery is put to the line, and the
zinc pole to earth. The connection with the copper pole in this case is through
the back contact of No. 2 key. No. 2 key may be a similar key to No. 1, but if so
all its connections are not required. When put down this key breaks the back
contact already referred to, and makes a front contact whereby the battery is
earthed in the middle, and, say, three-quarters of the battery is short circuited,
supposing the key No. 1 to be up. A weak zinc current then flows into the line.
If No. 1 key is down at the same time as No. 2 the connection between the line and
battery is cut off, and no current passes.
The arrangements at the receiving end may be as illustrated by diagram B, or
they may be modified as shown by diagram G, the line current being split equally
between the two relays of No. 2 receiving instrument, and then brought together
and passed through the relay of No. 1 instrument to earth. A relay may be put
into the local circuit to operate the receiving instrument, and the receiving instru-
ment may be so worked indirectly. This arrangement has some advantages.
These arrangements are applicable when by the ordinary duplex methods both
ends of the line are enabled to transmit simultaneously.
The arrangements may be modified so that one key may transmit a copper
current, the other a strong zinc, and both key down simultaneously a weaker zinc,
and so forth. Similarly arrangements may also be made to work with three
strengths of current.
In some cases in order to prevent breaks in the signals we employ a relay which
maintains the contact whilst the tongue is travelling, and breaks contact only when
it comes against the insulated stop.
For example, in the arrangement shown in Diagram D the receiving instrument
No. 2 should indicate both copper and strong zinc currents, but when a change
occurs from one to the other there. will necessarily be an instant when there is no
current in the line. In this instant (unless provision be made) there will not be
contact at either relay, and a break in the signal will occur, but this is obviated
when the relay levers are made by means of light springs to continue the con-

page_text: tacts during a portion of the time whilst the levers are travelling between the
stops.
We employ a similar contrivance in connection with the transmitting arrange-
ment of cable lines. As is illustrated by the diagram E we cause the depression of
the key to complete a local circuit, in which a relay, such as above described, is
included. Immediately the tongue of the relay leaves its stop it makes contact with
a spring X, and puts the main battery on to the cable, and it remains on whilst the
tongue of the relay is travelling. As the tongue reaches its further stop it passes
off the spring; the main battery is taken off, and a second weaker battery is
applied, which remains on until the finger key rises. The finger key, in rising in
the manner already described, breaks the connection of the main battery with the
spring X at the same time that it breaks the local circuit; it may also by the back
contact, as the diagram indicates, make contact for a reversing battery, which is
commonly used in cable telegraphy.
The use of the auxiliary battery to continue the current is not essential; oven
without it a dash will be produced if the key will be held down in consequence of
the discharge of the cable being delayed.
Having thus described the nature of our said Invention, and the manner of per-
forming the same, we would have it-understood that we claim,—
First. The means for transmitting two messages simultaneously in the same
direction through the same wire, substantially as described.
Second. The means for making contacts for a cable, or analogous line, by means
of a key operating in conjunction with a relay, substantially as described.
In witness whereof, we, the said Sir James Anderson and William Henry
Ash, have hereunto set our hands and seals, this 29th day of June, 'in
the year of our Lord One thousand eight hundred and seventy-six.
JAMES ANDERSON