IM- PROVEMENTS IN THE RECEIVING INSTRUMENTS OF ELECTRIC TELEGRAPHS, AND IN RECORDERS FOR OTHER USES
Year: 1877

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LETTERS PATENT to John Muirhead, junior, and Alexander Muirhead, both of
29, Regency Street, in the City of Westminster, for the invention of IM-
PROVEMENTS IN THE RECEIVING INSTRUMENTS OF ELECTRIC TELEGRAPHS, AND
IN RECORDERS FOR OTHER USES."
Sealed the 5th February 1878, and dated the 17th August 1877.
PROVISIONAL SPECIFICATION left by the said John Muirhead and Alexander
Muirhead at the Office of the Commissioners of Patents' on the 17th August
1877.
JOHN MUIRHEAD, junior, and ALEXANDER MUIRHEAD, both of 29, Regency Street,
in the City of Westminster. "IMPROVEMENTS IN THE RECEIVING INSTRUMENTS OF
ELECTRIC TELEGRAPHS AND IN RECORDERS FOR OTHER USES."
The following improvements are intended to be applied to apparatus in which
it is required to record the movements of light bodies influenced by very slight
forces:-
The forms of apparatus to which these improvements can best be applied are
those based on the principles described in the Patents, No. 9745, May Twenty-
seventh, One thousand eight hundred and forty-three, and No. 3059, December
twenty-fourth, One thousand eight hundred and fifty-six, taken out by Bain and
Varley respectively.
They consist essentially of a rectangular coil of insulated wire suspended, free to
vibrate, between the poles of a permanent horse-shoe magnet; or of two horse-shoe
magnets with opposite poles facing each other, or of powerful electro-magnets
similarly placed, the axis of the coil being at right angles to the axes of the
magnets, motion of the coil being produced by the reversal of the direction of the
electric current. The magnets are preferably fixed, so that the magnetic rays are
concentrated through the coils of wire, the magnets being placed both inside and
outside the coil, and surrounding the latter as much as possible.
The coil is suspended by two spiral springs coiled in opposite directions, and
rigidly attached at their inner ends to the top and bottom of the moveable coil, the

page_text: whole being sustained by a single fibre at the top.
With this mode of suspension it
is advantageous to use alluminium wire for the coil, thereby diminishing greatly the
resistance of the body to motion.
The movements of the coil are recorded on a travelling strip of paper by means
of a fine glass syphon dipping at the upper end into a reservoir of ink, and facing
the paper at the lower end. This syphon is connected by cords to arms projecting
from the moveable coil.
To produce and maintain a flow of ink from the syphon to the paper without
introducing resistance to the motion of the moveable coil we employ the following
methods: A fine platinium wire is inserted in the glass syphon, dipping at one end
into the reservoir of ink and terminating at the other end near to the point of the
syphon facing the paper. By connecting the ink reservoir and paper roller to the
terminals of the secondary circuits of a Rhumkorff's coil or other induction apparatus,
a. continuous discharge of comparatively low tension electricity is maintained
between the point of the platinium wire and the paper roller, which drives the
column of ink before it on to the paper running between the syphon and the roller;
or a metallic syphon terminating in a point of glass or other non-conducting
material may be substituted for the glass syphon and platinium wire described; or
other means may be adopted by which the syphon is made more conductive than
the ink throughout its length to within a short distance of the point facing the
paper on which the records are to be made.
The line of ink may be adjusted to a suitable degree of fineness by varying the
distance of the end of the platinium wire from the point of the syphon; the nearer
the wire is to the end of the syphon the finer will be the line.
To facilitate the adjustment of the primary current a separate coil and battery
are used to work the make-and-break piece of the primary circuit; the separate
coil will act on a long tuning fork carrying contact springs.
In order to increase the dynamical value of the conducting circuit of the receiving
instrument in electric telegraphs notion is given to one part of the circuit relatively
to the other. One method of effecting this is to introduce into the circuit of the
receiving instrument two coils of wire, one within the other, and to give to these
rapid motion in planes at right angles to each other. Whatever current flows
through the wire, of these coils will be rapidly increased from the electro-magnetic
induction of one part of the same current on another according to Amphère's rule,
and the current so increased will have increased effect on the magnetic needle within
a coil forming part of same circuit.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Muirhead and Alexander Muirhead in the Great Seal Patent
Office on the 16th February 1878.
JOHN MUIRHEAD, junior, and ALEXANDER MUIRHEAD, both of 29, Regency Street,
in the City of Westminster. "IMPROVEMENTS IN THE RECEIVING INSTRUMENTS OF
ELECTRIC TELEGRAPHS, AND IN RECORDERS FOR OTHER USES."
The following improvements are intended to be applied to apparatus in which
it is required to record the movements of light bodies influenced by very slight
forces.
The forms of apparatus to which these improvements can best be applied are
those based on the principles described in the Patents No. 9745, May 27th, 1843,
and No. 3059, December 24th, 1856, taken out by Bain and Varley respectively.
They consist essentially of a rectangular coil of insulated wire suspended, free to
vibrate, between the poles of a permanent horse-shoe magnet, or of two horse-shoe
magnets with opposite poles facing each other, or of powerful electro-magnets
similarly placed, the axis of the coil being at right angles to the axes of the
magnets, motion of the coil being produced by the reversal of the direction of the
electric current. The magnets are preferably fixed, so that the magnetic rays are
concentrated through the coils of wire, the magnets being placed both inside and
outside the coil, and surrounding the latter as much as possible.
The coil is suspended by two spiral springs coiled in opposite directions, and
rigidly attached at their inner ends to the top and bottom of the moveable coil, the
whole being sustained by a single fibre at the top. With this mode of suspension it
is advantageous to use aluminium wire for the coil, thereby,diminishing greatly the
resistance of the body to motion.
The movements of the coil are recorded on a travelling strip of paper by means
of a fine glass siphon dipping at the upper end into a reservoir of ink, and facing
the paper at the lower end. This siphon is connected by cords to arms projecting
from the moveable coil.
To produce and maintain a flow of ink from the siphon to the paper without
introducing resistance to the motion of the inoveable coil we employ the following
methods: A fine platinum wire is inserted in the glass siphon, dipping at one end
into the reservoir of ink, and terminating at the other end near to the point of the
siphon facing the paper. By connecting the ink reservoir and paper roller to the
terminals of the secondary circuit of a Rhumkorff's coil or other induction apparatus,
a continuous discharge of comparatively low tension electricity is maintained
between the point of the platinum wire and the paper roller, which drives the
column of ink before it on to the paper running between the siphon and the roller;
or a metallic siphon terminating in a point of glass or other non-conducting
material may be substituted for the glass siphon and platinum wire described; or
other means may be adopted by which the siphon is made more conductive than
the ink throughout its length to within a short distance of the point facing the
paper on which the records are to be made.
The line of ink may be adjusted to a suitable degree of fineness by varying the
distance of the end of the platinum wire from the point of the siphon; the nearer
the wire is to the end of the siphon the finer will be the line.
In order that our said invention may be most fully understood and readily
carried into effect, we will proceed to describe the Drawing hereunto, annexed.
DESCRIPTION OF THE DRAWING.
The Drawing shows receiving and recording apparatus constructed according to
our Invention.
A is the receiving coil forming part of the line circuit, and suspended in a
powerful magnetic field. Its weight is sustained by the fibre B. C and D are two

page_text: .
coiled springs, one placed over and the other below the coil; one end of each of
these springs is fastened to a suitable support, and the other end is attached to a
stem A¹, A¹, fixed securely to the coil A. The springs C and D are coiled in
opposite directions; the supports by which they are carried are adjustable, and by
these adjustments a tendency of suitable strength is given to the coil to assume a
E is an arm
properly selected position when uninfluenced by an electric current.
attached to the coil, and a fine fibre E¹ passes from it to the arm F which is fixed
upon a strained wire G. The wire carries the siphon H, which is attached to it by
cement, and the lower end of the siphon is able to vibrate. I and K are springs
similar to the spring C and D. They are attached to the strained wire G, and
they are adjusted so as to ensure that at all times the fibre E¹ shall be held in
tension, so that the motion of the siphon may correspond accurately to that of the
coil A. I is the ink vessel. M is a inetal roller rotated by clockwork or otherwise,
and carrying forward continuously the strip of paper N intended to receive the
record. The ink vessel L and the roller M are in connection with an induction
apparatus, and the siphon H is so arranged that it will conduct freely to within a
short distance of its lower end, where it faces the paper N; but for the remainder
of its length it is made of an insulating material, so that a continuous or nearly
continuous electric discharge may pass between the ink at the end of the siphon to
the paper N and the roller M, which discharge will carry the ink along with it.
We prefer to make the siphon of a fine or capillary glass tube, and to insert into
it a very thin platinum wire of such a size as to enter it freely, and terminating at
a short distance above the orifice at its lower end. This wire is best inserted before
bending the glass tube into the siphon-like form. As before mentioned, however,
there are other methods by which the siphon may be rendered conducting to within
a short distance of its point, so that the electric discharge for carrying forward the
ink may have but a short space to traverse. This arrangement allows of electricity
of a much lower tension being employed than is requisite when a simple glass
siphon is employed, as in the instrument known as the Thomson recorder.
Having thus described the nature of our said Invention and the manner of
performing the same, we would have it understood that we claim,-
First. The employment of opposed springs in hanging the receiving coil A,
substantially as described.
Second. The arrangement of the siphon H in such manner that the electricity
employed to promote the discharge of the ink may be conducted along it freely and
independently of the ink which the siphon contains nearly to the delivering orifice,
substantially as described.
Third. The use in combination of the induction coil as the source of electricity
for carrying forward the ink, and of a conducting siphon for conveying the
electricity nearly to the point from which the delivery of the ink is required,
substantially as described.
In witness whereof, I, the said John Muirhead, have hereunto set iny hand
and seal, this Sixteenth day of February, in the year of our Lord One
thousand eight hundred and seventy-eight.
J. MUIRHEAD, JB. (L.S.)