IMPROVEMENTS IN THE MODE OF AND APPARATUS FOR APPLYING ELECTRICITY TO GIVE TELEGRAPHIC SIGNALS AND WORK TELEGRAPHIC RELAYS
Year: 1875

page_text: LETTERS PATENT to Sir Charles Wheatstone, Knight, of Park Crescent,
Regent's Park, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN THE MODE OF AND APPARATUS FOR APPLYING ELECTRICITY
TO GIVE TELEGRAPHIC SIGNALS AND WORK TELEGRAPHIC RELAYS.”
Sealed the 28th September 1875, and dated the 5th August 1875.
PROVISIONAL SPECIFICATION left by the said Sir Charles Wheatstone
at the Office of the Commissioners of Patents, with his Petition,
on the 5th August 1875.
I, Sir CHARLES WHEATSTONE, Knight, of Park Crescent, Regent's
Park, in the County of Middlesex, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE MODE OF AND APPARATUS FOR
APPLYING ELECTRICITY TO GIVE TELEGRAPHIC SIGNALS AND WORK TELEGRAPHIC
RELAYS," to be as follows:-
My present Invention consists in a method or methods of employing
for telegraphic purposes the motions produced when mercury is in
contact with an electrolytic liquid within a tube of narrow calibre and
electric currents are transmitted through them.

page_text: The urst part of my invention relates to the employment of these
motions as telegraphic signs, instead of the motions of magnetised
needles within electric coils, or other means having the same object in
view which are at present in use.
The second part of my Invention relates to the employment of these
motions for the purpose of completing one or two local circuits by
which a telegraphic instrument, either recording, permanent, or giving
fugitive signs, or producing sounds, may be brought into action by
means of electric currents transmitted through the main circuit.
th
The following is one manner in which the first part of my said
Invention may be carried into effect:-A capillary tube, about ¼ of
an inch internal diameter and about 6 inches in length, turned upwards
at its ends, and terminating at its vertical ends in two reservoirs or
cups, is fixed horizontally on a board having adjusting screws for the
purpose of obtaining a proper level. This tube is filled with mercury,
which rises into the cups and nearly fills them; but in the middle of the
capillary tube a small quantity of dilute sulphuric acid or other con-
ducting electrolytic liquid is introduced, occupying a space of about a
quarter of an inch more or less, and kept in the middle by proper
levelling. Immediately above the cups and plunging into the mercury
are two platina wires, insulated except at their extremities, so that they
may not come in contact with any electrolytic liquid at the surface;
these wires are in metallic connection with binding screws, which are
connected one with the telegraphic line wire, and the other with the
earth wire.
The transmitting instrument placed at the other end of the telegraphic
line is a current inverter with two keys connected with a voltaic
battery, which according as the one or the other key is touched transmits
a positive or a negative current to the line; the motion of the mercury
thread in the receiving relay is always in the direction of the current
that is from the copper to the zinc poles of the battery through the
telegraphic line.
The construction of a current inverter with two keys being well
known need not here be described.
When a key is kept depressed and the current consequently
continues in the same direction, the column of mercury moves con-

page_text: tinuously forward towards one of the reservoirs. This motion may by
means of the reversing key at the transmitting station be checked,
intermitted, or reversed, so that all the signals which a single needle
magnetic telegraph is capable of showing may be exhibited at the
receiving station. The motions, whether they follow in the same or in
opposite directions, are distinctly marked and may be casily read.
A single voltaic element of small dimensions will cause these motions
If the
through many hundred miles of standard telegraphic wire.
power employed be too great the column of mercury will have a
tendency to divide itself, but this, if not carried too far, will not injuriously
affect the indications. The same construction of the transmitting key
is (equally applicable when the Morsc alphabet is to be employed;
the manipulation only will be different. The succession of long and
short currents, which in this alphabetic system constitutes the sign of
a letter, is effected by successively touching the same key; but a
different key must be touched for cach alternate letter.
A great
advantage is hereby obtained; the change of direction in the motions
indicates clearly the transition from one letter to another, so that no
error can arise from the running of the dots and dashes of one letter into
those of the subsequent onc.
Instead of the electrolytic thread dividing a mercury column as above
described the capillary tube and reservoirs may be filled with the
electrolytic liquid and the short space with mercury, or one-half of the
tube may be filled with mercury and the other half with the electrolytic
liquid; in all these cases the motions at the points of junction of the
two liquids may be equally well observed, but I prefer the method above
described.
To render the indications of the mercury thread more visible I place
the tube in a camera arrangement, so that the image of the mercury and
liquid thread is magnified and thrown on a ground glass screen, before
which the observer places himself. Or the indications may be photo-
graphed by throwing the image of the mercury thread thus formed on
sensitive paper moving with a continuous motion in any of the methods
employed in self-registering meteorological instruments.
Secondly. I will now proceed to describe in what manner I employ
the motions of mercury in contact with an electrolytic liquid in a
capillary tube for the purpose of acting as a relay to a local circuit

page_text: containing a telegraphic instrument so as to produce the proper series
of motions necessary to work it efficiently.
If the telegraphic instrument placed in the local circuit be constructed
with an electro-magnet, so that its motions are produced by the alternate
action of an electric current and a reacting spring, or, if it be so con-
structed as to produce marks by means of the action of a current in one
direction only on chemically prepared paper, the means I adopt to cause
the motions of the mercury in the tube to open and close the circuit
containing the telegraphic instrument are somewhat as follows:-
th
The mercurial relay is a glass tube, the internal diameter of which is
about of an inch, more or less. It is bent upwards at its two ends,
whilst the intermediate portion remains horizontal, and is placed on a
frame which is held in position by a clamp. An insulated pillar has an
arm, which carries at its end a platinum wire or steel needle, which by
means of an adjusting screw may be brought nearly to the level of the
mercury in the tube. The pillar and the arm have each an adjustment,
so that the wire may be brought in the same line with the bore of the
tube. Two platinum wires are inserted in the side of the tube touching
the mercury within it. The outer ends of these platinum wires dip into
two small cups containing mercury, or are clamped in binding screws.
The tube is charged with mercury, excepting a small space between the
platinum wires, which is filled with the electrolytic liquid; or several
small spaces thus filled may be interposed in the mercury thread between
the insertions of the wires as the sensibility of the motions appear
hereby to be increased. If a platina wire be used for the plunger this
liquid may be diluted sulphuric acid; but if a steel wire be employed,
which is preferable on account of its having less adhesion to mercury
than platina has, I recommend the employment of dilute carbolic acid.
The adhesion of platina wire is reduced by coating it with black lead.
The connection of this relay with the local circuit containing the
telegraphic instrument and with the line is as follows:-The local circuit
consists of the receiving telegraphic instrument and a voltaic battery,
consisting of one or more elements. One pole of this local circuit is
connected with the plunger, and the other with the platina wire passing
through the side of the tube into the mercury thread. One platina
wire is connected with the telegraphic line, and the other with the carth
line, or, if the station is an intermediate one, with the continuation of

page_text: the telegraphic line, alternately inverted currents being sent through
the line from the transmitting station. When the current is in one
direction the mercury in one end of the tubes is raised, and that in the
other end is depressed, and the mercury in the former touching the wire
completes the circuit. When the current is in the opposite direction the
mercury in the former falls and breaks the circuit, while it rises in the
other. The durations of the currents and intervals in the local circuit
depend on the respective intervals between the alternate currents in the
transmitting instrument.
When a telegraphic instrument of the "Morse " construction is
placed in the receiving local circuit a current inverter with two keys
must be placed at the transmitting station.
When the printing receiver of my automatic telegraphic system
described in the Specification of Letters Patent granted to me dated
January 28th 1867, No. 220, is placed in the local circuit the adjustment
of the armature of the clectro-magnet must be so set as to allow it to
act only on one side, so that the marking roller is removed from the
paper by the reacting spring instead of by a reverse current. The trans-
mitter of that system, described in the same Specification, must be
placed at the transmitting station.
I mention these two telegraphic systems as they are those most
generally adopted in this country, but it is easy to see what modifi-
cations are necessary to enable other instruments to work by means of
this relay; but in all cases it is necessary that the transmitting instru-
ment shall be actuated by alternately inverted currents.
A different arrangement of the mercurial relay is required when it is
applied to telegraphic receiving instruments which are actuated by
currents in alternate opposite directions and worked by electro-magnets.
The sole difference in the construction of the relay is that a similar
plunger, and with the same adjustments as that applied to one end of
the tube, is applied also on the other end. The electro-magnet of the
receiving instrument is surrounded by two independent coils. The ends
of one of these coils are connected respectively with the plunger and one
of the platina wires, and the ends of the other with the other plunger
and the other platina wire. Two equal voltaic batteries are placed in the
two circuits thus formed.

page_text: The action consequent on this arrangement is as follows:-When the
line current is positive the mercury in one end of the tube ascends and
completes the circuit, and the armature is attracted in one direction;
but when it is negative the mercury in the other end ascends and
completes the circuit, which causes the armature to be attracted in the
opposite direction. The same transmitters at the sending station are
suitable for the relay with double local circuit as for the relay with a
single local circuit previously described.
the County of Middlesex, one of the Executors of Sir Charles
Wheatstone, Knight, who departed this life on the 19th day of
October 1875, late of Park Crescent, Regent's Park, in the County
of Middlesex, in the Great Seal Patent Office on the 28th January
1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
SABINE, of Cumberland Terrace, Regent's Park, in the County of
Middlesex, one of the Executors of Sir CHARLES WHEATSTONE, Knight,
late of Park Crescent, Regent's Park, in the County of Middlesex, who
departed this life on the Nineteenth day of October, One thousand eight
hundred and seventy-five, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of August, in the year of
our Lord One thousand eight hundred and seventy-five, in the thirty-
ninth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto him, the said Sir Charles Wheatstone, Her special license
that he, the said Sir Charles Wheatstone, his executors, administrators,
and assigns, or such others as he, the said Sir Charles Wheatstone, his
executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ircland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN THE MODE OF AND APPARATUS FOR APPLYING ELECTRICITY

page_text: TO GIVE TELEGRAPHIC SIGNALS AND WORK TELEGRAPHIC RELAYS," upon the
condition (amongst others) that he, the said Sir Charles Wheatstone,
his executors or administrators, by an instrument in writing under
his, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in
what manner the same was to be performed, and cause the same
to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters
Patant

page_text: nearly fills them; but in the middle of the capillary tube a small
quantity of dilute sulphuric acid or other conducting electrolytic
liquid is introduced, occupying a space of about a quarter of an inch
more or less, and kept in the middle by proper levelling. Immediately
above the cups a, d, and plunging into the mercury, are two platina
wire i, i, insulated, except at their extremities, so that they may not
come in contact with any electrolytic liquid at the surface. These wires
i, i, are in metallic connection with binding screws 1, 2, which are
connected, one with the telegraphic line wire and the other with the
earth wire.
The transmitting instrument, Figure 2, placed at the other end of the
telegraphic line, is a current inverter E, with two keys m, n, connected
with a voltaic battery V, which, according as the one or the other key is
touched, transmits a positive or a negative current to the line. The
motion of the mercury thread in the receiving relay is always in the
direction of the current, that is, from the copper to the zinc poles of
the battery through the telegraphic line. The construction of a current
inverter with two keys being well known, need not here be described..
When a key is kept depressed and the current consequently continues
in the same direction the column of mercury moves continuously
forward towards one of the reservoirs a, d. This motion may, by
means of the reversing key at the transmitting station, be checked,
intermitted, or reversed, so that all the signals which a single needle
magnetic telegraph is capable of showing may be exhibited at the
receiving station. The motions, whether they follow in the same or in
opposite directions, are distinctly marked, and may be casily read. A
single voltaic element of small dimensions will cause these motions
through many hundred miles of standard telegraphic wire. If the
power employed be too great the column of mercury will have a
tendency to divide itself, but this, if not carried too far, will not
injuriously affect the indications. The same construction of the trans-
mitting key is equally applicable when the "Morse" alphabet is to be
employed; the manipulation only will be different. The succession of
long and short currents which in this alphabetic system constitutes the
sign of a letter is effected by successively touching the same key, but
a different key must be touched for each alternate letter.
A great
advantage is hereby obtained; the change of direction in the motions
indicates clearly the transition from one letter to another, so that no

page_text: error can arise from the running of the dots and dashes of one letter
into those of the subsequent one.
Instead of the electrolytic thread dividing a mercury column as above
described, the capillary tube b, c, and reservoirs a, d, may be filled with
the electrolytic liquid, and the short space with mercury, or one half of
the tube may be filled with mercury and the other half with the
electrolytic liquid; in all these cases the motions at the points of
junction of the two liquids may be equally well observed, but the method
above described is preferable.
To render the indications of the mercury thread more visible the
tube b, c, may be placed in a camera arrangement, so that the image of
the mercury and liquid thread is magnified and thrown on a ground
glass screen, before whichthe observer places himself. Or the indications
may be photographed by throwing the image of the mercury thread
thus formed on sensitive paper, moving with a continuous motion in
any of the methods employed in self-registering meteorological
instruments.
Secondly, I will now proceed to describe in what manner the motions
of mercury in contact with an electrolytic liquid in a capillary tube are
employed for the purpose of acting as a relay to a local circuit con-
taining a telegraphic instrument, so as to produce the proper series of
motions necessary to work it efficiently.
If the telegraphic instrument placed in the local circuit be constructed
with an electro-magnet, so that its motions are produced by the alternate
action of an electric current and a reacting spring, or if it be so
constructed as to produce marks by means of the action of a current in
onc direction only on chemically prepared paper, the means adopted to
cause the motions of the mercury in the tube to open and close the
circuit containing the telegraphic instrument are somewhat as follows:-
th
The mercurial relay is represented at Figure 3. It consists of a glass
tube a, b, c, d, the internal diameter of which is about " of an inch,
more or less; it is bent upwards at its two ends a, d, whilst the
intermediate portion b, c, remains horizontal and is placed on a frame
A, B, C, D; it is held in position by a clamp c. An insulated pillar f
has an arm g, which carries at its end a platinum wire or steel needle h,
which by means of an adjusting screw may be brought nearly to the
level of the mercury in the tube. The pillar fand the army have each

page_text: an adjustment, so that the wire may be brought in the same line with
the bore of the tube. Two platinum wires i, i, are inserted in the side
of the tube, touching the mercury within it; the outer ends of these
platinum wires dip into two small cups k, l, containing mercury or are
clamped in binding screws. The tube is charged with mercury
excepting a small space between the platinum wires, which is filled with
the electrolytic fluid. Or several small spaces thus filled may be
interposed in the mercury thread between the insertions of the wires,
as the sensibility of the motions appears hereby to be increased. If a
platina wire be used for the plunger this liquid may be diluted sulphuric
acid, but if a steel wire be employed, which is preferable, on account of
its having less adhesion to mercury than platina has, it is recommend
to employ dilute carbolic acid.
The connection of this relay with the local circuit containing the
telegraphic instrument and with the line is as follows:-
The local circuit consists of the receiving telegraphic instrument E,
and a voltaic battery V, consisting of one or more elements. One pole
of this local circuit is connected with the plunger / by means of the
binding screw o, and the other with the nearest platina wire passing
through the side of the tube a, b, c, d, into the mercury thread. Onc
platina wire is connected with the telegraphic line, and the other with
the earth line by means of the binding screws, or if the station is an
intermediate one with the continuation of the telegraphic line.
Alternately inverted currents being sent through the line from the
transmitting station, when the current is in one direction the mercury
in one end of the tube is raised and that in the other end is depressed,
and the mercury in the former touching the wire h completes the circuit.
When the current is in the opposite direction the mercury in the
former falls and breaks the circuit while it rises in the other. The
durations of the currents and intervals in the local circuit depend on the
respective intervals between the alternate currents in the transmitting
instrument.
When a telegraphic instrument of the "Morse" construction is placed
in the receiving local circuit a current inverter with two keys must be
placed in the transmitting station.
When the printing receiver of the automatic telegraphic system described
in the Specification of Letters Patent granted to the late Sir C. Wheat-

page_text: stone, dated January 28th 1867, No. 220, is placed in the local circuit
the adjustment of the armature of the electro-magnet must be so set as
to allow it to act only on one side, so that the marking roller is removed
from the paper by the reacting spring, instead of by a reversed current.
The transmitter T of that system described in the same Specification
must be placed at the transmitting station.
I mention these two telegraphic systems, as they are both well known
in this country, but it is easy to see what modifications are necessary to
enable other instruments to work by means of this relay, but in all cases
it is necessary. that the transmitting instrument shall be actuated by
alternately inverted currents.
A different arrangement of the mercurial relay is required when it is
applied to telegraphic receiving instruments which are actuated by
currents in alternate opposite directions, and worked by electro-magnets.
The sole difference in the construction of the relay represented at
Figure 4 is that a similar plunger and with the same adjustments as
that applied to one end of the tube is applied also on the other end.
The electro-magnet E of the receiving instrument is surrounded by two
independent coils; the ends of one of these coils are connected respec-
tively with the plunger and one of the platina wires i, i, and the ends
of the other with the other plunger and the other platina wire i. Two
equal voltaic batteries V, V, are placed in the two circuits thus formed.
The action consequent on this arrangement is as follows:-When the
linc current is positive the mercury in one end of the tube ascends and
completes the circuit, and the armature is attracted in one direction, but
when it is negative the mercury in the other end ascends and completes
the circuit, which causes the armature to be attracted in the opposite
direction. The same transmitters at the sending station are suitable for
the relay with double local circuit as for the relay with a single local
circuit previously described.
Having now described the said Invention of a new method of giving
telegraphic signs and constructing telegraphic relays, I would here.
remark that although in the course of the aforesaid description I have
necessarily mentioned many contrivances already known and in use, such
as the telegraphic receiving instruments placed in the local circuit, and
the telegraphic transmitting instruments placed in the main line, I wish
it to be understood that I make no claim for them, but only for the

page_text: means by which they are connected with this system; but what I claim
as the said Invention is as follows:-
First. Employing for telegraphic signals the motions produced when
mercury is in contact with an electrolytic liquid within a tube of narrow
calibre and electric currents are transmitted through them, and the means
substantially as herein shown and described for carrying the same into
effect.
Secondly. Employing the aforesaid motions for the purpose of com-
pleting one or more local circuits by which a telegraphic instrument may
be brought into action by means of electric currents transmitted through
the main circuit, and the means substantially as herein shown and
described for carrying the same into effect.
In witness whereof, I, the said Robert Sabine, have hereunto set
my hand and scal, this Fourteenth day of December, in the year
of our Lord One thousand eight hundred and seventy-five.
BADAR