IMPROVEMENTS IN ELECTRIC TELEGEAPHS."
Year: 1866

page_text: LETTERS PATENT to Samuel Manley Martin, of Harrow-on-the-Hill, in
the County of Middlesex, Samuel Alfred Varley, of 66, Roman Road.
Holloway, and Frederick Henry Varley, of 337, Kentish Town Road,
both in the County of Middlesex, Telegraph Engineers, for the Invention
of "IMPROVEMENTS IN ELECTRIC TELEGEAPHS."
PROVISIONAL SPECIFICATION left by the said Samuel Manley Martin.
Samuel Alfred Varley, and Frederick Henry Varley, at the Office of the
Commissioners of Patents, with their Petition, on the 31st March 1866.
We, SAMUEL MANLEY MARTIN. of Harrow-on-the-Hill, in the County of
Middlesex, SAMUEL ALFRED VARLEY, of 66, Roman Road, Holloway, and
FREDERICK HENRY VARLEY, of 337. Kentish Town Road, both in the County
of Middlesex. Telegraph Engineers, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN ELECTRIC TELEGRAPHS," to be as follows:
Our improvements chiefly relate to electric telegraphs for signalling trains,
but parts of the Invention relate to nearly all electric telegraphs.
In constructing telegraphs for what is known as the block system, the wires
are terminated at certain poles situated at a convenient distance from one
another by shackles, and the electric continuity maintained by a loop of wire
connecting the line wires on either side of the shackles; the loops are made of
such a length that the middle portion is within easy reach of a man, and they
are prevented touching the pole by being bound round an insulator at the
middle of the loop. When an interruption occurs on the railway, the guard
cuts the loop and breaks the electric continuity, which reveals to the signalling
stations on either side of the severed loop that the line is interrupted. When
.”

page_text: The line wires are terminated
an insulator to the pole at a
the cause of the interruption has been removed the guard restores the electric
continuity by twisting the severed ends of the loop together, and reports what
he has done to the station master at the next station, whose duty it is to
acquaint the nearest telegraphic inspector or mechanic, who should immediately
proceed to the spot and properly repair it. It occasionally occurs, either from
the guard omitting to report his having cut the loop wire, or the telegraphic
workman neglecting his duty, or some such cause, the divided loop is not
properly repaired, and the temporary joint made by the guard after a time
fails, giving a false sigual, and delaying the traffic: the loop wires also being
made of slight wire, are sometimes broken by accidental causes. We remedy
these defects by a different construction of loop.
by shackles in the usual way; we then attach
convenient height for a man to reach. In this insulator a piece of metal having
a female screw tapped in it is fixed, we prefer this piece of metal to be of
brass or copper tinned. A piece of wire or a stranded wire is soldered to the
line wire on one side of the shackle, and brought down and soldered to the
piece of metal fixed in the insulator. A similar piece of stranded wire is sol-
dered to the line wire on the other side of the shackle, and terminates in a
metal plate with a hole in it. This plate is placed over the piece of metal fixed
in the insulator, and firmly clamped to it by means of a screw having a suitable
shoulder. In the head of the clamping screw there are two holes passing
through it at right angles to each other. After the screw has been screwed
down a piece of wire is threaded through one of the holes and soldered to the
stranded wires on either side; the object of this is to ensure more perfect elec-
tric continuity. We prefer in all cases to employ stranded wires for the loops,
and prefer them to be made of copper wire tinned. When the
guard wants to break electric continuity he cuts the wire threaded
through the head of the clamping screw, and unscrews by means of
a key the clamping screw, and divides the loop; when he wishes to restore
the continuity he screws the stranded wires together again, and reports what
he has done to the next station. It is now the duty of the line man to proceed
to the spot and thread another wire through the head of the clamping screw,
and solder it to the stranded wires on either side. Should, however, he
neglect to do this the electric continuity will still be maintained by the screw.
When an interruption occurs stopping the traffic on only one pair of metals,
say the up line, for instance, it is the duty of the guard to divide the up line
telegraph loop only; but not having any guide to distinguish the up line from
the down line wire except his printed instructions. which may not be close at
hand, and not liking to trust his memory, he, to make sure, sometimes cuts

page_text: both loops, and thus delays the traffic on both the down as well as the up line.
To prevent this we mark the loop insulators with D. L. on the down line, and
U. L. on the up line, or with other suitable characters, so that the guard
immediately secs which is the right loop to be divided.
Railways worked under the block system of signalling are divided into sec-
tions with electric signalling stations at the end of each section, and where
the block system is strictly carried out only one train is allowed to be in a
section at a time. It is common practice, however, when the traffic is a mixed
one, and the stations are a considerable distance apart, to allow three or four
or more trains in a section. For example, if a passenger train be proceeding
in the direction from A to B, A may have a series of slow trains waiting in a
siding for the passenger train to pass, when A has notification of the passenger
train being on the road, he signals to B, and by a series of previously arranged
signals, consisting of different numbers of beats- of the needle, he informs him
of the passenger train and of the slow trains following it; B acknowledges
cach signal, and blocks the needle over to train on line. Directly the passenger
train has passed A allows the slow trains to enter the section.
When this practice prevails B has to trust: to his memory to
remember the trains on the section both on the up line and on the down line,
should he report the line as clear before all the trains have passed him, a
fast train may be allowed to enter the section, and a collision may be the
consequence. We remedy this by attaching to the instrument two tablets, one
we generally place on the top, and the other just over the handle. The upper
plate has a number, of holes corresponding to the greatest number of trains
which can be permitted to be on the section at one time, and there is an arrow
engraved on this plate to show the direction of the trains. The lower plate
has a greater number of holes, and simply serves as a receptacle to hold a
number of pins ready for use. The pins are numbered to correspond witlf
the beats of the needle, which signify the nature of the train. For example,
one beat of the needle may indicate a passenger train, two beats a goods,
three beats a ballast; four a mineral train, and so on. Now, supposing A has
signalled to B a series of trains in the above order, B removes a peg with
No. 1 on it from the lower plate, and places it in the upper plate near the
arrow head on receiving notification of a goods; next he places a pin with
No. 2 engraved on it next to No. 1 peg, and so on as they are successively
signalled to him by A. As the trains arrive at B he removes the pegs and
places them in the lower plate, and when all have passed he gives the signal
line clear.
Another serious defect it railway signalling circuits arises from the difficulty

page_text: experienced in making good contact with the earth.
We make our earth
contact in the following way:-We take a piece of ordinary gas barrel, which
may be of any suitable length and diameter; one end of the gas barrel may
be closed and pointed; in some cases a cast iron or a steel point is fitted into
the end, according to the nature of the ground. We construct a clamp, which
embraces the gas barrel, and takes apart in two halves, and also a weight with
a hole through it large enough to pass freely over the gas barrel. The gas
barrel is passed through the hole in the weight, and the clamp is attached to
the barrel below the weight; the gas barrel is then placed in a vertical position,
and the weight raised and allowed to drop. The descent of the weight is
assisted by the clamp, and the barrel is forced into the ground; when the
barrel is forced so far down that the clamp comes into contact with the earth,
the clamp is readjusted higher up, and this process is continued until nearly
the whole of the barrel is forced into the earth. To facilitate the driving in
we generally make use of a pulley working in a sheave, and so arranged that
it can readily be fitted on to the top of the gas barrel; a rope is passed over
the pulley and attached to the weight, which can be wound up and allowed
to fall. In this way the gas barrel is readily forced into the earth to a very
considerable depth, and good contact ensured. Metal rods may be employed
in place of the gas barrel, but we prefer to use gas barrel. We also prefer
the gas barrel to be galvanized.
For tunnel circuits, where it is important a very clear description of the
train should be signalled, we do not rely upon a certain number of beats for
signifying the nature of the train approaching, but construct our instruments
as follows:
We make a series of electro-magnets and arrange them in a circle on an
iron plate; these magnets are at equal distances from one another and generally
arranged in pairs, so that they may be opposite one another on each side of the
circle, and each magnet connected with the one immediately opposite it. The
insulated wire is so wrapped that the poles of each pair of magnets is of the
opposite character, the one being north and the other south, or vice versa.
The number of electro-magnets employed depends upon the number of signals
required, each pair of electro-magnets giving two signals. Over the poles of
the electro-magnets a permanent or induced magnet is mounted on an axis
terminating in pivots, the lower pivot rests on a spring which can be adjusted
to the requisite degree of strength on the upper pivot, a light indicator which
may either be a disc of mica or a light pointer is fixed. When a disc of mica
is used the signals are painted on the disc on lines radiating from the centre
to the circumference. An opaque screen with a slot on one side is placed

page_text: above the mica disc, and the signals arrange themselves under this slot in
accordance with the electro-magnet rendered active. When a pointer is used
in place of the mica disc it moves over a dial on which the signals are painted
and takes up its position in the same way as described with the mica disc.
When a current is sent through one pair of the electro-magnets the mounted
magnet immediately flies round and arranges itself over the active electro-magnet,
and is attracted down and its motion arrested on the current being removed,
the spring on which the pivot of the mounted magnet rests raises it above the
poles of the electro-magnet, leaving it free to move in any direction; to assist.
the action of this spring the electric current after passing through the electro-
magnets previously to its entering the earth is made to pass through another
electro-magnet, over which, but insulated from it, a series of convolutions of
insulated wire (technically known as a secondary wire) are wrapped, the ends
of the secondary wire are connected to a series of coils wrapped on the poles
of the electro-magnets, but insulated from them; on removing the current from
the electro-magnets a momentary current is developed in the secondary wire,
and this current passes through the coils of the electro-magnets. The secondary
current passes round the electro-magnets in the opposite direction to
the current previously passing through, and momentarily magnetizes
the electro-magnets in the opposite direction, the effect of this is
counteract any residual magnetism in the electro-magnets, and
to liberate the mounted magnet carrying the indicater. In some
cases we substitute circular coils for the electro-magnets, or we construct
the electro-magnets with iron cores that do not come up to the surface of the
coil. When we use coils we prefer placing over each coil, or pairs of coils,
a permanent magnet of a horse-shoc form, each of these magnets carries a
screen covering 2 letters; a positive current deflects the magnet in one direc-
tion, revealing one of the letters, and a negative current deflects it on the
opposite side revealing the others. The electric current is sent by means of
a commutator of the following construction:-A circular piece of metal is first
divided into two halves, one of these halves is further divided into as many
segments as there are line wires. Two levers insulated from, but attached to
one another, which we call the battery arms, are mounted on a vertical axle
and work over the divided circle, one of them being in contact with the entire >
half circle, the other with the segments. On the axle carrying the battery
arms there is a pointer which points to the signals which are painted outside
the commutator in a circle. The positive pole of a galvanic battery is con-
nected to one of the battery arms, the negative pole with the other. The entire
half circle forming part of the commutator is connected to the earth, the seg-
to

page_text: has a
ments to the line wires; on moving the pointer round a half circle a series of
positive currents are sent through the line wires in succession, and on moving
it over the other half a series of negative currents are sent through the line
wires. When circular coils are used in place of electro-magnets the commu-
tator is constructed semewhat differently: A circle of ebonite is placed within
the devided circular piece of metal, the battery arms rest upon the ebonite and
are prevented from coming in contact with the metal segments. Opposite to the
centre of the segments notches are cut in the ebonite ring to allow the battery
arms to drop in and come into contact with the metallic segments when desired.
The axis carrying the battery arms
vertical motion of about
of an inch, and there is a spring attached to its lower part
pulling it down. When sending with this commutator the axis is
pulled up by means of a handle or button attached to it, and the pointer moved
round until it is opposite the signal, the battery arms are then allowed to drop
into the notches, and a current is sent which reveals the desired signal. This
instrument may be used for a speaking telegraph; when used for this purpose
twelve wires will be sufficient, and the commutator may be made with a series
of keys working like pianoforte keys with letters of the alphabet engraved on them.
The way we construct the instruments when we use circular coils is as
follows:We take pieces of tube of a slightly larger diameter than the coils;
we cut this tube into rings of the same width as the thickness of the coils; we
call these rings the coil boxes; we also cut rings out of the same tube of the
width of the space desired between the coils for the magnet to work between.
and call them space rings. We now place the coil boxes with a space ring
between each pair into other pieces of tube which fit tightly over them, these
outer pieces of tube hold the coil boxes together, and are of such a length that
when placed centrally they cover the space ring and embrace both coil boxes,
leaving the coil boxes projecting an of an inch, more or less, at both ends.
The coil boxes are now clamped into their places between two plates of metal
and soldered to the plates. The plates are then fixed in their position and
attached to one another by pillars and screws, or any suitable way. The plates
are now separated, and the space rings and the outer pieces of tube which
held the boxes together removed, and the coils placed in the coil boxes. The
magnets are mounted on axles terminating in pivots and work between the
two coils, one end of the axle passes through one of the plates which forms
the front of the instrument and works on a pivot hole in a bridge. The letters
or signals are painted on the front of the instrument, and screens depend fron
the axles and cover them until the coils are rendered active by an electri
current passing through..

page_text: We employ a modification of the construction just described in some cases,
which is simpler but not so sensitive. We take a plate which may be of metal
or any suitable substance and bore a series of circular holes through it, the
circular coils fit into these holes flush with the surface. Only one circular
coil is used in this arrangement for each horse-shoe magnet. The magnets
are mounted on axles and work over the surface of the coils, and carry screens
which cover the signals in the manner previously described, the signals are
painted on thin sheets of cardboard, which fit closely to the surface of the
coils.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Samuel Manley Martin, Samuel Alfred Varley, and Frederick
Henry Varley in the Great Seal Patent Office on. the 28th September
1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, SAMUEL
MANLEY MARTIN, of Harrow-on-the-Hill, in the County of Middlesex, SAMUEL
ALFRED VARLEY, of 66, Roman Road, Holloway, and FREDERICK HENRY
VARLEY, of 337, Kentish Town Road, both in the County of Middlesex, Tele-
graph Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirty-first day of March, in the year of our Lord
One thousand eight hundred and sixty-six, in the Twenty-ninth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us, the
said Samuel Manley Martin, Samuel Alfred Varley, and Frederick Henry
Varley, Her special licence that we, the said Samuel Manley Martin, Samuel
Alfred Varley, and Frederick Henry Varley, our executors, administrators, and
assigns, or such others as we, the said Samuel Manley Martin, Samuel Alfred
Varley, and Frederick Henry Varley, our 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 Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN ELECTRIC TELEGRAPHS," upon the condition
(amongst others) that we, the said Samuel Manley Martin, Samuel Alfred
Varley, and Frederick Henry Varley, our executors or administrators, by an
instrument in writing under our, or one of our, or their, or one of their hands
and seals, should particularly describe and ascertain the nature of the said

page_text: 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 Patent.
NOW KNOW YE, that I, the said Samuel Alfred Varley, on behalf of
myself and of the said Samuel Manley Martin and Frederick Henry Varley,
do hereby declare the nature of the said Invention, and in what manner
the same is to be performed. to be particularly described and ascertained in
and by the following statement and accompanying Drawings, that is to
say:-
Our improvements chiefly relate to electric telegraphs for signalling trains,
but parts of the Invention relate to nearly all electric telegraphs.
In constructing telegraphs for what is known as the block system the wires
are terminated at certain poles situated at a convenient distance from one
another by shackles, and the electric continuity maintained by a loop of wire
connecting the line wires on either side of the shackles the loops are made of
such a length that-the middle portion is within easy reach of a man, and they
are prevented touching the pole by being bound round an insulator at the
middle of the loop. When an interruption occurs on the railway the guard
cuts the loop and breaks the electric continuity, which reveals to the signalling
stations on either side of the severed loop that the line is interrupted. When
the cause of the interruption has been removed the guard restores the electric
continuity by twisting the several ends of the loop together, and reports what
he has done to the station master at the next station. whose duty it is to
acquaint the nearest telegraphic inspector or mechanic, who should immediately
proceed to the spot and properly repair it; it occasionally occurs. either from
the guard omitting to report his having cut the loop wire, or the telegraphic
workman neglecting his duty. or some such cause. the divided loop is not
properly repaired. and the temporary joint made by the guard after a time
fails, giving a false signal and delaying the traffic: the loop wires also being
We remedy
made of slight wire are sometimes broken by accidental causes.
We terminate the
these defects by a different construction of loop (Fig. 1).
line wires by shackles in the usual way, and then attach an insulator to the
In this insulator a piece
pole at a convenient height for a man to reach.
of metal having a female screw is fixed. we prefer this piece of metal to be
of brass or copper tinned. A piece of wire or a stranded wire is soldered to
the line wire on one side of the shackle, and brought down and soldered to
the piece of metal fixed in the insulator. A similar piece of stranded wird
is soldered to the line wire on the other side of the shackle, and terminates in
a metal plate with a hole in it, or the metal plate may be forked; this plate

page_text: is placed over the piece of metal fixed in the insulator, and firmly clamped
to it by means of a screw having a suitable shoulder. The head of the clamp-
ing screw is made with one or more holes through it. After the screw has been.
screwed down a piece of wire is threaded through the head of the clamping
screw and soldered to the stranded wires on either side, the object of this is to
ensure more perfect electric continuity. We prefer in all cases to employ
stranded wires for the loops, and prefer them to be made of copper wire tinned.
When the guard wants to break electric continuity he cuts the wire threaded
through the head of the clamping screw, unscrews the clamping
screw, and divides the loop. When he wishes to restore the continuity he
screws the stranded wires together again and reports what he has done to the.
next station. It is now the duty of the lineman to proceed to the spot and
thread another wire through the head of the clamping screw and solder it to
the stranded wires on either side. Should, however. he neglect to do this the
electric continuity will still be maintained by the screw. When an interrup-
tion occurs stopping the traffic on only one pair of metals. say the up line,
for instance, it is the duty of the guard to divide the up fine telegraph loop
only; but not having any guide to distinguish the up line wire from the down
line wire except his printed instructions which may not be close at hand and
not liking to trust his memory he to make sure sometimes cuts both loops,
and thus delays the traffic on both the down as well as the up line. To pre-
vent this we mark the loop insulators with D. L. on the down line, and U. L.
on the up line, or with other suitable characters, so that the guard immediately
secs which is the right loop to be divided.
Railways worked under the block system of signalling are divided into sections
with electric signalling stations at each end of the section, and where the block
system is strictly carried out only one train is allowed to be in a section at the
same time. It is however a common practice where the traffic is a mixed one.
and the stations a considerable distance apart. to allow more than one train to he
in a section. For example. if a passenger train be proceeding in the direction
from A to B. A may have a series of slow trains waiting in a sliding for the pas-
senger train to pass: when A has notification of the passenger train being on the
road he signals to B. and by previously arranged signals consisting of different
numbers of beats of the needle. he informs him of the passenger train, and of
the slow trains following it; B ackowledges each signal and blocks the needle
over to train on line. Directly the passenger train has passed. A allows the
slow train to enter the section. When this practice prevails B has to trust
to his memory to remember the trains on the section. both on the up line and
on the down ne. should he report the line as clear before all the trains have

page_text: passed him a fast train may be allowed to enter the section, and a collision
may be the consequence. We remedy this by attaching to the instrument tw
tablets or plates (Fig. 2), one we generally place on the top of the instrument
and the other over the handle. The upper plate has a number of holes corre
sponding to the greatest number of trains which can be permitted to be in a
section at the same time. There is either an arrow engraved on the upper
tablet to show the order in which the trains are proceeding, or
the tablet is engrave opposite the holes first train, second train,
third train, fourth train, as shewn in Figure 2, (four trains being assumed to
be the greatest number which can be permitted in a section. The lower plate
has a greater number of holes than the upper tablet, and serves simply as a
receptacle to hold the pegs ready for use. The pegs are numbered to corre-
spond with the beats of the needle, which signify the nature of the train. For
example, one beat of the needle may signify a passenger train, 3 beats a ballast,
and 4 a mineral train, and so on. Now suppose A has signalled to B a series
of trains in the above order; B removes a peg with No. 1 on it from the lower
plate and places it in the upper tablet opposite; first train, on receiving notifi-
cation of a ballast train he places a peg with No. 2 engraved on it next to
No. 1 peg, and so on as they are successively signalled to him by A; as the
trains arrive at B he removes the pegs and places them in the lower plate, and
when all have passed he gives the signal line clear.
Another serious defect in railway signalling circuits arises from the difficulty
experienced in making good contact with the earth. We make our earth
contact in the following way:- We take a piece of ordinary gas barrel
(Fig. 3), which may be of any suitable length and diameter, one end of the
gas barrel may be closed and pointed, in some cases a cast iron or a steel
point is fitted into the end according to the nature of the ground.
We con-
struct a clamp which embraces the gas barrel, and takes apart in two halves,
and also a weight with a hole through it large enough to pass freely over the
gas barrel. The gas barrel is passed through the hole in the weight, and the
clamp is attached to the barrel below the weight, the gas barrel is then placed
in a vertical position and the weight raised and allowed to drop. The descent
of the weight is arrested by the clamp, and the barrel is forced into the ground;
when the barrel is forced so far down that the clamp comes into contact with
the earth the clamp is re-adjusted higher up. and this process is continued
until nearly the whole of the barrel is forced into the earth. To facilitate the
driving in we generally make use of a pulley working in a sheave, and so
arranged that it can readily be fitted on to the top of the gas barrel; a rope
is passed over the pulley and attached to the weight, which can be wound up

page_text: and allowed to fall. In this way the gas barrel is readily forced into the
earth to a very considerable depth and good contact ensured; metal rods
may be employed in place of the gas barrel, but we prefer to use gas barrel;
we also prefer the gas barrel to be galvanized.
For tunnel circuits, where it is important a very clear description of the
tmin should be signalled, we do not rely upon a certain number of beats for
signifying the nature of the train approaching, but construct or instruments
as follows:-We make a series of electro-magnets and arrange the poles
radially in a circle on an iron plate (Fig. 4); these magnets are at equal dis-
tances from one another and generally arranged in pairs, so that they may be
diametrically opposite one another on each side of the circle, and each magnet
is connected with the one immediately opposite it, the insulated wire is so
wrapped that the poles of each pair of magnets is of the opposite character
the one being north and the other south, or vice versa. The number of
electro-magnets employed depends upon the number of signals required, each
pair of electro-magnets giving two signals. Over the poles of the electro-
magnets a permanent or an induced magnet is mounted on an axis termi-
nating in pivots, the lower pivot rests on a spring which can be adjusted to
the requisite degree of strength, on the upper pivot a light indicator, which
may either be a disc of mica, or a light pointer is fixed.
When a disc of
mica is used the signals are painted on the disc on lines radiating from the
centre to the circumference. An opaque screen with a slot on one side is
placed above the mica disc, and the signals arrange themselves under this slot
in accordance with the electro-magnet rendered active. When a pointer is
used in place of the mica disc it moves over a dial on which the signals are
painted, and takes up its position in the same way as described with the mica
disc opposite the desired signal. When a current is sent through one pair of
the electro-magnets the mounted magnet immediately flies round and arranges
itself over the active electro-magnet and is attracted down, and its motion
arrested; on the current being removed the spring on which the pivot of the
mounted magnet rests raises it above the poles of the electro-magnet, leaving it
free to move in any direction; to assist the action of this spring the electric current
after passing through the electro-magnets previously to its entering the earth,
is made to pass through another electro-magnet (Fig. 5), over which, but
insulated from it, a series of convolutions of insulated wire (technically known
as a secondary wire) are wrapped, the ends of the secondary wire are connected
to a series of small coils wrapped on the poles of the electro-magnets, but
insulated from them; on removing the current from the electro-magnets a
momentary current is developed in the secondary wire, and this current passes

page_text: through the small coils of the electro-magnets. The secondary current passes
round the electro-magnets in the opposite direction to the current previously
passing through and momentarily magnetizes them in the opposite direction;
the effect of this is to counteract any residual magnetism in the electro-
magnets, and to thereby liberate the mounted magnet carrying the indicator.
In some cases we substitute circular coils for the electro-magnets, or we
construct the electro-magnets with iron cores that do not come up to the sur-
face of the coil. When we use coils we prefer placing over each coil or pairs
of coils a permanent horse-shoc magnet (Figs. 12 and 14), each of these
magnets carries a screen covering two letters or signals, a positive current
deflects the magnet in one direction, revealing one of the signals, and a nega-
tive current deflects it on the opposite side revealing the other, as indicated by
the dotted lines. The electric current is sent by means of a commutator
(Figs. 6 and 7) of the following construction:-A circular piece of metal is
first divided into two halves, one of these halves is further divided into as
many segments as there are line wires. Two levers insulated from but
attached to one another, which we call the battery arms, are mounted on a
vertical axle and work over the divided circle, one of them being in contact
with the entire half circle, the other with the segments. On the axle carrying
the battery arms there is a pointer which points to the signals which are
painted outside the commutator in a circle, the positive pole of a galvanic
battery is connected to one of the battery arms, the negative pole with the
other. The entire half circle forming part of the commutator is connected to
the earth, the segments to the line wires. On moving the pointer round a
half circle a series of positive currents are sent through the line wires in suc-
cession, and on moving it over the other half a series of negative currents are
sent through the line wires. When circular ccils are used in place of electro-
magnets the commutator is constructed somewhat differently (Figs. 8 and 9).
A circle of ebonite is placed within the divided circular piece of metal; the
battery arms rest upon this ebonite, and are thereby prevented from coming
in contact with the metal segments. Opposite to the centre of the segments
notches are cut in the ebonite ring to allow the battery arms to drop in and
come into contact with the metallic segments when desired. The axis carrying
the battery arms has a vertical motion of about a quarter of an inch, and there
is a spring attached to its lower part pulling it down. When sending with
this commutator the axis is pulled up by means of a handle or button attached
to it, and the pointer moved round until it is opposite the signal, the battery
arms are then allowed to drop into the notches, and a current is sent which
reveals the desired signal. This instrument is intended chiefly for tunnel

page_text: circuits and train signalling, but it may be used for a speaking telegraph.
When used for the latter purpose twelve wires will be sufficient, and the com-
mutator may be made with a series of keys working like pianoforte keys
with letters of the alphabet engraved on them.
The way we construct the instruments when we use circular coils is as
follows: We take pieces of tube (Figs. 10 and 11) of a slightly larger
diameter than the coils; we cut this tube into rings of the same width as
the thickness of the coils, we call these rings the coil boxes; we also cut
rings out of the same tube of the width of the space desired between the
coils for the magnet to work between and call them space rings.
We now
place the coil boxes with a space ring between each pair into other pieces of
tube which fit tightly over them; these outer pieces of tube hold the coil
boxes together, and are of such a length that when placed centrally they cover
the space ring and embrace both coil boxes, leaving the coil boxes projecting
an eighth of an inch, more or less, at both ends. The coil boxes are now
clamped into their places between two plates of metal (Fig. 11) and. soldered
to the plates; the plates are then fixed in their position and attached to one
another by pillars and screws or any suitable way. The plates. are now
separated, and the space rings and the outer pieces of tube which held the
boxes together removed, and the coils placed in the coil boxes. The magnets
(Figs. 13 and 15) are mounted on axles terminating in pivots, and work
between the two coils; one end of the axle passes through one of the plates,
which forms the front of the instrument, and works in a pivot hole in a
bridge, the other pivot works in a pivot hole at the back of the instrument.
The letters or signals are painted on the front of the instrument, and screens
are attached to the axles and cover them until the coils are rendered active
by an electric current passing through.
We employ a modification of the construction just described in some cases
which is simpler but not so sensitive. We take a plate, which may be of metal
or any suitable substance, and bore a series of circular holes through it, 'the
circular coils fit into these holes flush with the surface only; one circular coil
is generally used in this arrangement for each horse-shoe magnet. 'The
magnets are mounted on axles and work over the surface of the coils and
carry screens which cover the signals in the manner previously described.
The signals are painted on thin sheets of cardboard, which fit closely to the
surface of the coils.

page_text: C represents the insulator; E, the clamping screw; F, F¹, the two stranded
wires soldered to the line wire on either side of the shackle, and which form
the loop; F is the plate, which is removed to divide the loop; G is the wire
which is threaded through the head of the clamping screw and soldered to the
stranded wires; H, H, is the telegraph pole, part of which only is shown.
Figure 2, I, I, represents an ordinary single needle-block instrument with
the tablets attached; J, J, is the lower plates which serves as a receptacle
for the pegs; K, the upper tablet, which is represented with a peg in the
upper hole.
Figure 3 represents the method of making contact with the earth. L, L, is
the gas barrel; M, the clamp; N, the weight; O, the pulley; P, the rope.
Figures 4 to 15 shows the construction of the tunnel signalling instruments.
Figure 4 is a top view of the instrument when electro-magnets are used;
Figure 5 shows the same instrument in elevation; the same letters refer to
each. Q, Q, Q, Q, are the electro-magnets; R, R, R, R, the small coils
wrapped on the poles of the electro-magnets, and in connection with the
secondary wire of the electro-magnet S; T is the magnet mounted on the
axle U which carries the indicator V; U' is the spring on which the lower
pivot rests.
Figure 6 is a top view of a part of the commutator; Figure 7 is the other
portion shown in elevation.
Figure 8 is the top view of the modification of the commutator, which is
employed when circular coils are used in place of electro-magnets; Figure 9
shows the same in elevation; the same letters refer to Figures 6, 7, 8, 9.
W, W, W, W, W1, is the circular piece of metal divided into the half circle Wi
and segments W, W, W, W; X, X, are the two battery arms which move over
the half circle and segments; Y is the insulating material between the two
battery arms separating the one from the other; D is the pointer attached to
the axle which carries the battery arms; Z is a forked spring which pulls
down the battery arms on to the metallic segments; it is shown separated in
Figure 7. a, a, Figures 8 and 9, is the ebonite ring; 1, 2, 3, 4, 5, 6, 7, 8, are
the notches cut into the ebonite ring, into which the battery arms X, X, drop
and come into contact with the metallic segments when required.
Figures 10 and 11 show the construction of the coil boxes, into which the
circular coils are placed. b, b, b', b', are the pieces of tube which form the
coil boxes; c is the space ring; d, d, is the outer tube which holds the coil
boxes in their places; e, e, e¹, e¹, are the two metal plates, to which the coil
boxes are soldered.
Figures 12, 13, 14, and 15 show the construction of the horse-shoe magnets

page_text: for the circular coils and the way they are mounted. Figure 12 is a front
view where only a pair of coils is used; Figure 13 is an edge view of the
same. Figure 14 is a front view where four coils are employed, and a double
horse-shoe magnet made in the shape of a letter H; Figure 15 is an edge
view of the same; the same letters refer to Figures 12, 13, 14, 15. f, f, is
the horse-shoe magnet mounted on the axle i and working over the surface of
and between the coils b, b, b, b; i is the bridge on the front plate of the
instrument e, e, in which the front pivot of the axle works; is the bearing
attached to the back plate of the instrument e', e, in which the other pivot of
the axle works.
Having now described the nature of our Invention, and in what manner
the same is to be performed, we wish it to be understood what we claim is.-
First, the constructing loop wires in the manner described.
Second, the indicating the number of trains in a section of railway in the
manner described.
Third, the making contact with the earth in the manner described.
Fourth, the liberating a magnet which has been attracted on to the poles of
an electro-magnet by means of a spring in conjunction with a current developed
in a secondary wire of an electro-magnet, as herein-before described.
Fifth, the general construction of the instrument, as described, in which
circular coils are used.
In witness whereof, I, the said Samuel Alfred Varley, on behalf of myself
and the said Samuel Manley Martin and Frederick Henry Varley, have
hereunto set my hand and seal, this Twenty-eighth day of September,
in the year of our Lord One thousand eight hundred and sixty-six.
SAMUEL ALFRED VARLEY. (L.S.)