IMPROVEMENTS IN ELECTRIC TELEGRAPH INSTRUMENTS
Year: 1870

page_text: LETTERS PATENT to Josiah Latimer Clark, of No. 5, Westminster
Chambers, Victoria Street, in the City of Westminster, for the
Invention of "IMPROVEMENTS IN ELECTRIC TELEGRAPH INSTRUMENTS."
Sealed the 2nd September 1870, and dated the 30th June 1870.
PROVISIONAL SPECIFICATION left by the said Josiah Latimer Clark
at the Office of the Commissioners of Patents, with his Petition,
on the 30th June 1870.
I, JOSIAH LATIMER CLARK, of No. 5, Westminster Chambers, Victoria
Street, in the City of Westminster, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN ELECTRIC TELEGRAPH INSTRUMENTS," to
be as follows :-
This Invention has for its object improvements in electric telegraph
instruments.
In order to record telegraphic signals. on a travelling strip of paper
or other fabric I cause an electro-magnet, when excited by a current
reaching it by a line wire, to give motion to a metal or other tube of

page_text: small diameter, and so to bring one end of it into contact with the
travelling surface. The other end of the tube is connected by a flexible
pipe with an ink reservoir, in which is a suitable and sufficiently fluid
ink, and the surface of the ink in the reservoir is nearly on a level with
the open end of the marking tube. Whenever the open end of this tube
is brought in contact with the travelling paper or surface it makes a dot
upon it, and if the contact be prolonged a line on the paper or surface
results. Two marking tubes may be caused to mark simultaneously on
the same travelling paper or surface, the signals being formed by com-
binations of the marks of the two tubes. The tubes may be both worked
by one line wire, either directly or by means of a relay. A relay may
also be applied to sound a pair of bells; the tone of the bells is different,
and one or other of them is struck as one or other of the marking
tubes is brought in contact with the travelling paper or surface.
In some cases the arrangement may be such that the marking tube
remains constantly in contact with the travelling paper or surface whilst
it is at work, the signal currents causing a motion of the marking tube
in directions at right angles to the direction of motion of the paper or
other surface. It is convenient for this purpose to couple the working
tube with a magnetic needle mounted between the poles of an electro-
magnet. The electro-magnet is provided with horns in such manner,
that it may in effect present to the needle four poles, two north poleṣ
on one side, but at opposite extremities of the needle, and two south
poles on the other side of the needle. All the poles act in unison when
a current enters by the line wire to cause the rotation of the needle a
short distance either way around its axis or centre, and this motion is
communicated to the marking tube.
The needle may be of steel or of soft iron, and a permanent magnet
is employed to induce magnetism into the needle; the poles of the per-
manent magnet are beyond those of the needle, and the position of the
permanent magnet may be adjusted to bring the needle to a central
position between the poles of the electro-magnet when no current is
passing.
In testing the resistance of electric telegraph lines an instrument
known as a differential galvanometer is used. It usually consists of two
cqual coils of a hollow cylindrical form, they are opposite in direction
the one to the other, and a needle is suspended within them. Theso
coils should when a current is caused to pass through them, half by

page_text: each coil, produce no effect on the needle, the one neutralizing the other,
and if they do not do so it is in consequence of one coil being nearer to
the needle than the other. I provide the means of adjusting the
distances at any time when it may be found requisite simply by arranging
the cylindrical coils to slide upon a hollow core which is fixed to the
base or frame of the instrument, and serves to carry them; or the coils
may be fixed, and the core may be moveable with them and be made to
carry the needle and its suspension.
J
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Josiah Latimer Clark in the Great Seal Patent
Office on the 30th December 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSIAU
LATIMER CLARK, of No. 5, Westminster Chambers, Victoria Street, in
the City of Westminster, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirtieth day of June, in the year of our
Lord One thousand eight hundred and seventy, in the thirty-fourth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Josiah Latimer Clark, Her special license that, I, the
said Josiah Latimer Clark, my executors, administrators, and assigns,
or such others as I, the said Josiah Latimer Clark, my 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, excrcise; and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
ELECTRIC TELEGRAPH INSTRUMENTS," upon the condition (amongst others)
that I, the said Josiah Latimer Clark, my executors or administrators,
by an instrument in writing under my, 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

page_text: 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.
+ I
NOW KNOW YE, that I, the said Josiah Latimor Clark, 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 thereof, that is to say :-
This Invention has for its object improvements in electric telegraph
instruments, and relates in part to instruments to record telegraphic
signals.
Figure 1 shews a side, and Figure 2 an end elevation of the working
portion of a recording instrument arranged according to my Invention.
The strip of paper or other material a is drawn over the roller 6 by the
ordinary mechanism of the Morse apparatus. c is the marking tube
which is actuated by the electro-magnet and armature d, e, and which
produces a mark or line upon the paper as often as the attraction of the
armature e brings it into contact. f is the reservoir containing the
supply of ink connected with the marking point c by means of
the flexible tube g. The horizontal axis h which support the armature
is a hollow tube, and the upright arm i which carries the marking point
is also hollow, so that the ink flows freely from the reservoir through
the tubes g, h, i, to the marking point, the only resistance to motion
being the flexure of the thin flexible tube g. If this flexible tube be of
india-rubber the ink employed must be of some aqueous liquid which
does not destroy it. The reservoir f is of such construction as to cause
"the ink to flow from it at a constant level. It consists of a metal or
glass cylinder with a small tube at the bottom closed by the tap j, the
nozzle of which is of convenient form to receive the flexible tube; it is
closed at the top by a moveable cover & which screws into it with an
air-tight collar; an open tube however descends through it nearly to
the bottom of the reservoir, through which the air is supplied as fast as
the liquid empties itself. The tube is formed conveniently for receiving
a cork or stopper to facilitate the refilling of the reservoir, and to enable
it to travel without spilling.
In using the apparatus the tap' is first of all closed, the cover k is
then removed and the vessel filled with ink, the cork being inserted in
the top of the tube / the cap is screwed into its place; on removing the
cork and opening the tap the reservoir is in action, the liquid now

page_text: flows freely from the marking point as long as its level is not higher
than the bottom of the tube ; a bubble of the air which descends
through the tube rises through the liquid in the reservoir from time
to time as the ink flows from the marking point, the supply being
quite independent of the level of the surface of the liquid within the
reservoir.
Instead of this form of reservoir I sometimes employ another instru-
ment, shewn in Figure 3; an inverted cylindrical vessel n filled with
ink is contained within a larger cylinder o, the bottom of n is constructed
with a narrow neck which is closed by a valve p working in guides.
When in position, as shewn in the Drawing, the valve p is raised by
its wire guide which rests on the bottom of the larger cylinder, the
ink therefore flows out until it attains the level of the bottom of the
inverted neck. It can then no longer flow since no more air can obtain
admission; as fast, however, as the ink is used from the outer vessel,
the level falls and bubbles of air enter the neck and allow more liquid
to flow out; the use of the valve p is to enable the inner vessel to be
lifted out without spilling the ink; in travelling the neck may be closed
by a cork or screw cap. The ink marks are produced most efficiently
when the acting level of the liquid is about a quarter of an inch above
the level of the marking point; there is, however, some risk of the
liquid flowing spontaneously at this level while the instrument is out
of action; to obviate this tendency the whole reservoir is mounted on a
vertical sliding bar connected with the stopping and starting lever, so
that it is raised about half an inch whenever the machine is set in
motion, and is depressed again when the machine is stopped, the
same lever which starts and stops the machine also lowers and raises
the reservoir.
To obviate any tendency of the liquid to become dry or thickened in
the mouth of the marking tube when it has been long out of use I
employ a small wire or piston p (Fig. 1) working in a small stuffing
box at the back of the point and capable of being thrust forward
through the mouth, this piston is withdrawn by a small spiral spring
within the stuffing box.
:
It is obvious that two such marking tubes may be used side by side
so as to form a double style apparatus by which a considerably higher
speed of working may be attained, the signals being then formed of
17

page_text: combinations of dots only, instead of dots and lines as in the ordinary
Morse arrangement.
י
My next improvement consists in electro-magnetic apparatus adapted
for working either land or submarine lines, the instrument may work
either as a relay or may give direct signals. In Figures 4, 5, and 6,
8, 81, and n, n¹, is a compound electro-magnet of the ordinary con-
struction with soft iron cores fixed upon the opposite ends of the
permanent steel magnets N, S, and N¹, S¹; these steel magnets polarize
the soft iron cores permanently in the directions indicated by the letters,
that is to say, the electro-magnet cores n, n¹, have both north polarity
and the cores 8, 81, both south polarity. Between the poles of this
electro-magnet a permanently magnetized needle n", 8", is supported
centrally upon pivots, its north end being between the poles n, n¹, and
.vice versa. By this disposition it is obvious that the north end of the
needle, s¹, being repelled by the two north poles of an electro-magnet
and the south end being repelled by the south poles of the electro-
magnet the needle will be forced to assume when at rest a central
position between them; the electro-magnet is wound with coils of wire
which are all connected together into one circuit in such a manner
that when a current passes round them the diagonally opposite poles of
the compound electro-magnet are respectively strengthened and weakened
so that the needle loses its balance and is deflected either in the one
direction or the other, that is to say, that when the current strengthens
the poles n, 8, and simultaneously weakens the poles n¹, s¹, the needle is
repelled from 1 and 8 respectively and attracted towards n' and 8', and
vice versa. Two stops or screws a, a, are supplied for making electrical
contacts, and thereby completing the circuit of a local battery in the
usual manner when the instrument is used as a relay.
,
In order more effectually to give a central position to the needle n¹¹, 811
a tangent screw b, b, with milled head is provided, working into a wheel c,
to which a weak spiral spring is fixed, after taking a few turns round the
axis of the needle to which its inner end is attached; or if it be desired
to use the instrument as a single current relay, by rotating this wheel in
one direction or the other the spring will cause the needle to rest with
more or less force against one or other of the stops a, a. It is obvious
that if the needle be set in its central position a current sent through
the electro-magnet will cause it to be deflected against one or other of

page_text: the stops, according to the direction of the current. In order still
further to strengthen the action of this relay a hollow coil may surround
the magnetic needle, but without being in contact with it, a separate
battery being put in circuit with the coil so as to maintain a continuous
current round it in the same sense as the magnetism of n", 81, such a
coil is shewn at d, d, Figure 7. By this arrangement the magnetic
intensity of the needle is strengthened; or if it be of soft iron is
maintained constant.
This apparatus may be combined with the printing arrangement
described in my first improvement. Another method of effecting this
is shewn in Figure 7, in which n", 8", represents the magnetic needle,
and n, s, the electro-magnet, as previously described. Upon the end
of the needle is fixed a very light arm of aluminum, terminating in a
small loop; a very fine flexible capillery tube descends from a reservoir
in the manner described in my first improvement, its lower extremity
being very near to, but not quite in contact with a strip of paper e, c,
which is drawn underneath it around the roller f. This roller has an
adjusting arrangement for elevating or depressing it, so as to bring the
paper into bare contact with the lower end of the marking tube. When
no current passes through the electro-magnet coils a continuous straight
line is drawn upon the paper when the latter is in motion, but as soon as
the current passes the magnet needle is deflected, and a deflection of the
inark will be made upon the paper to the right or left, according to the
direction of the current. The combination of right and left marks form
an alphabet, as in the ordinary telegraph signals. This apparatus may
also be constructed so that the needle when deflected may strike a light
hammer against two bells, in such a manner as to allow the signals to
be read by sound, either in combination with or without the marking
point and paper strip. Other magnets, for instance, as shewn at
N, S, in the Drawing, may further be employed, the direction of
the poles of which either attract or repel the magnetism of the
needle n", 8", according to the construction of the instrument. Instead
of the printing arrangement I sometimes attach a mirror to the
needle 2, 81, so as to read the signals reflected from it by a spot of
light upon a scale; in such case the needle is made extremely short and
light, and the poles of the magnets are altered in shape, so as to
accommodate the altered length.

page_text: My next improvement relates to a method of adjusting the magnetic
moment of a differential galvanometer suitable for testing electric
telegraph instruments.
Figure 8 is a plan, partly in section, of a differential galvanometer
constructed according to my Invention.
a, a, is the coil with the two wires b, b', and c, c', wound at once upon
the bobbin, in the usual manner, taking care that electrical resistance is
the same in both. When the bobbin is nearly full of wire I separate
the two wires, and finish winding with one of the wires at one end of
the bobbin, and with the other at the other end. The needle d is a very
short one, and carries a mirror, as in the ordinary mirror galvanometer.
This mirror is suspended within the bobbin from the arm e. It is fixed
in a sliding frame f, and support outside the coil with a screw g, by
which it may be advanced and adjusted a little on either side of the
centre of the bobbin, so as to conveniently find the point where the
action of the two coils is neutral. The instrument then becomes a
perfect differential galvanometer. The advantage of this system is,
that in the event of the needle being destroyed it may be replaced, and
the neutral point corresponding to the new needle readily found.
Having thus described the nature of my said Invention and the
manner of performing the same, I would have it understood that what
I claim as my improvements in electric telegraph instruments is,―
First. The combination of the marking tube supplied with ink from
a reservoir with electro-magnetic apparatus, by which the tube can be
moved to and from a travelling strip of paper or other material, which
is thus marked so as to record the movements of the marking tube.
Second. The combination of the marking tube supplied with ink from
a reservoir, and arranged so that the ink at its extremity remains in
contact with a travelling strip of paper or other material with electro-
magnetic apparatus, by which the marking tube can be moved trans-
versely to and fro over the travelling surface, which is thus marked so
as to record the movements of the marking tube.
Third. The general arrangement of the apparatus shewn by Figures
1, 2, 3, and 7.
Daunth
The construation of alectro maanotic annaratus consisting of

page_text: opposite magnetic repulsions, the balance of which can be disturbed by
passing an electric current through the coils of the instrument, so as to
cause the needle to move either way, according to the direction in which
the current passes.
Fifth. The construction of electric telegraph testing instruments,
known as differential galvanometers, with the two coils separated
sufficiently the one from the other, and adjustable by varying the
position of the needle between the coils.
In witness whereof, I, the said Josiah Latimer Clark, have hereunto
set my hand and seal, this Thirtieth day of December, in the
year of our Lord One thousand eight hundred and seventy.
JOSIAH LATIMER CLARK. (L.S.)