IMPROVEMENTS IN ELECTRIC TELEGRAPHS, AND IN THE APPARATUS USED IN WORKING THE SAME." PROVISIONAL SPECIFICATION
Year: 1859

page_text: LETTERS PATENT to Josiah Latimer Clark, of Haverstock Hill, and John
Muirhead, of Gloucester Road, Regent's Park, both in the County of
Middlesex, for the Invention of "IMPROVEMENTS IN ELECTRIC TELEGRAPHS,
AND IN THE APPARATUS USED IN WORKING THE SAME."
PROVISIONAL SPECIFICATION left by the said Josiah Latimer Clark
and John Muirhead at the Office of the Commissioners of Patents, with
their Petition, on the 20th January 1859.
We, JOSIAH LATIMER CLARK, of Haverstock Hill, and JOHN MUIRHEAD, of
Gloucester Road, Regent's Park, both in the County of Middlesex, do hereby
declare the nature of the Invention for "IMPROVEMENTS IN ELECTRIC TELE-
GRAPHS, AND IN THE APPARATUS USED IN WORKING THE SAME," to be as.
follows:-
In constructing the iron arms or brackets which are used for supporting the
line wire insulators, the horizontal portion of the support or bracket is cast
hollow or tubular, using malleable cast iron for the purpose, and subsequently
annealing the same, though other cast iron may be employed, by which means
the arms or brackets are made stronger without increasing their weight.
In order to preserve gutta percha or india-rubber_covered telegraph wires,
when laid underground or in troughs, and to prevent the damage which is
sometimes occasioned in such wires by lightning at those points where under-
Pr

page_text: ground and above ground wires are united, the coated wires, cither singly or
bound up in a mass, are immersed in soft pitch, asphalte, or resin, or in a
partially fluid compound containing such matters. In doing this, we prefer
to pour a layer of melted asphalte into the troughs at a temperature of not
more than 90° of Fahrenheit, so as not to incur any risk of damaging the
gutta percha. Two or three coated wires are then laid into the asphalte, and
pressed down beneath its surface; a second layer of asphalte is then added,
and more wires pressed in, until the required number is deposited in the
trough; more asphalte is then added, and then the cover of the trough is
fastened on. We find it is necessary that the asphalte or other pitchy com-
pound should be so softened by tar or other liquid, that when quite cold it
may always remain soft or partially fluid, so that the point of the finger may
be pressed into it, and the wires if necessary drawn out of the trough for
examination or repair, for if the asphalte is hard and brittle, it is liable to
become cracked, and water getting into the cracks impairs the insulating
and preserving property of the asphalte. Sand or other cheap earthy matters
may be mixed with the asphalte, whereby its cost may be reduced without
detriment to its protective properties.
In order to preserve the gutta percha and india-rubber of coated or covered
wires from decay, more especially those portions of gutta perchȧ or india-
rubber coated wires which are used above ground or are exposed to the
weather, we serve or cover the said gutta percha or india-rubber with a
coating of fine fibres of glass spun into yarn or cord, and saturated with pitch,
shellac, or other similar well-known oily or resinous material or compound.
The strands of glass fibre are wound or plaited on to the coated wire, and it is
preferred to paint the whole over with a coating of paint or tar. When glass
fibres are use for protecting the gutta percha or india-rubber used in insu-
lating above ground wires at the points where they are supported, we prefer
to take a tube of gutta percha or of vulcanite or vulcanized india-rubber, and
to cover it with the strands of spun glass, afterwards to slip it along the line
wire at the time of its erection, and to attach the tube to a telegraph post or
insulator.
Iu constructing lightning conductors to prevent the danger and damage
which occur to the telegraphic instruments and operators when the line wires
are struck by lightning, we take flat slabs of slate, wood, plaster of Paris
or other non-conducting material, and bore a number of holes through then
about a quarter of an inch in diameter; the slab is then laid on a flat face
plate of iron, and a short-pointed brass pin is dropped into each hole with its
point resting on the face plate. Fluid plaster of Paris is then poured overthe

page_text: whole to cement the pins in their places, and when set, melted lead, solder, or
other metal is poured on the top in such manner as to place the whole
of the pins in metallic connection; suitable terminals are added for the con-
nection of the line wires, and the whole is fitted in a wooden frame or box.
By these means the whole of the points of the brass pins are set exactly in the
same plane, and when placed on a perfectly flat metal plate which is connected
with the earth with an intervening piece of bibulous paper or muslin, they
form an efficient lightning conductor.
Heretofore in testing the state of the insulation of telegraph wires, it has
been customary to employ two different kinds of galvanometers or detectors,
one wound with fine wire for ordinary use, and another wound with thick wire
for measuring the force of batteries, and called a "quantity" detector.
Now, in constructing a detector according to our Invention, we wind it with
fine wire in the ordinary manner, and in addition we lead a short length of a
few yards of very fine wire from one terminal to the other, so that when any
galvanic current is passed through the instrument, a portion of the current
only goes through the galvanometer coil of the instrument, and the remainder
and greater portion passes through the short wire; and since the relative
proportion of the two quantities always remains constant, the whole quantity
passing is indicated as accurately as if it all passed through the galvanometer
coil. A switch enables the short wire to be thrown into circuit or out of circuit
at pleasure, and converts the instrument at will either into a "quantity"
detector or an intensity" detector.
In order to form standard detectors, and to enable the indications of such
instruments to be comparable and be kept constant, a test coil is added to
each instrument; this consists of a reel or coil of exceedingly fine wire with a
suitable terminal attached to it on the exterior of the instrument so arranged
that the current may be passed both through this resistance coil and through
the galvanometer coils. If a current from a single cell of a battery be thus
passed through the instrument and its coil, it will be found that down to a
very small limit the indication of the needle will be the same whatever be the
size of the battery plate employed, and this indication being made constant for
every instrument and recorded on its face, the operator can at any time verify
the correctness of his instrument by trying the effect of one cell of a battery.
upon
it. Without this fine wire resistance coil, the deflection caused by one
cell of a battery varies so greatly with the size of the plates that no practical
use can be made of the indication thus obtained.
The auxiliary coils are also useful for reducing the strength of what is
technically called the "return current" in submarine cables, and thus enabling

page_text: their length or the distance of a fault to be determined by a galvanometer
which would otherwise have been too delicate for the purpose. In order t>>
render the magnets, employed for magnetizing the needles of telegraphic
instruments and detectors more suitable for the purpose, we form them of the
usual horse-shoe form, and at the back or bend of the horse-shoe we hinge the
plates one into another so that their ends may be opened or separated, and we
introduce a spring tending at all times to keep them open. We cap the poles
or ends of the magnet with two wrought-iron curved horns, which come into
close contact when the magnet is closed, and the narrow curved horns are of
such a shape as to permit a needle to be magnetized without taking the coil
to pieces.
It is known that a magnet, with its armature constantly drawn away by a
weight which it can just support, will retain its magnetism unimpaired, or
even increase its strength, while under ordinary circumstances it would lose its
magnetism. The spring above described, has a similar effect.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Josiah Latimer Clark and John Muirhead in the Great
Seal Patent Office on the 20th July 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOSIAH
LATIMER CLARK, of Haverstock Hill, and JOHN MUIRHEAD, of Gloucester
Road, Regent's Park, both in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of January, in the year of our
Lord One thousand eight hundred and fifty-nine, in the twenty-second
year of Her reign, did, for Herself, Her heirs and successors, give and grant
unto us, the said Josiah Latimer Clark and John Muirhead, Her special
licence that we, the said Josiah Latimer Clark and John Muirhead, our
executors, administrators, and assigns, or such others as we, the said Josiah
Latimer Clark and John Muirhead, 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, än Invention for "IMPROVE
MENTS IN ELECTRIC TELEGRAPHS, AND IN THE APPARATUS USED IN WORKING THE
SAME," upon the condition (amongst others) that we, the said Josiah Latimer
Clark and John Muirhead, our executors or administrators, by an instrument

page_text: in writing under our or their hands and seals, or under the hand aud seal of
one of us or them, 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
Patent.
NOW KNOW YE, that I, the said Josiah Latimer Clark, on behalf of
myself and the said John Muirhead, 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:-
In constructing the iron arms or brackets which are used for supporting the
line wire insulators, the horizontal portion of the support or bracket is cast
hollow or tubular, using malleable cast iron for the purpose, and subsequently
annealing the same, though other cast iron may be employed, by which means
the arms or brackets are made stronger without increasing their weight.
Figure 1 is a side view, Figure 2 a front view, and Figure 3 a longitudinal
section of a bracket, constructed according to our Invention ;.it is cast in
malleable cast iron, and annealed as is usual in inaking articles of malleable
cast iron.
a, a, are screw holes, by which it is attached to a wooden post;,
and b is a socket to receive an iron stem c, shown in dotted lines, on the top
of which the insulator is fixed.
Inorder to preserve the gutta percha and india-rubber of coated or covered
wires fromdecay, more especially those portions of gutta percha or india-rubber
coated wires which are used above ground, or are exposed to the weather, we
serve or cover the said gutta percha or india-rubber with a coating of fine
fibres of glass spun into yarn or cord, and saturated with pitch, shellac, or
other suitable well-known oily or resinous material or compound. The strands
of glass fibre are wound or plaited on to the coated wire, and it is preferred to
paint the whole over with a coating of paint or tar.
In carrying out this part of our Invention, the glass is drawn out into
filaments or fibres, as is well understood, and it is then preferred to make it
into a loosely twisted yarn of about th of an inch in diameter, and to run
the yarn through melted bitumen, or to saturate it with any of the matters
above named, or other matters suitable for the purpose (bitumen is, however,
preferred); with the yarn thus preferred the gutta percha or india-rubber
coated wires are surrounded, by preference, by paying the yarns round them;
afterwards the whole may be coated, if desired, with paint or tar..
When glass fibres are used for protecting the gutta percha or india rubber

page_text: used in insulatingabove ground wires, at the points where they are supported;
we prefer to take a tube of gutta percha, or of vulcanite or vulcanized india-
rubber, and to cover it with the strands of spun glass, afterwards to slip it along
the line wire at the time of its erection, and to attach the tube to a telegraph
post or insulator. In this case the yarn is manufactured and saturated, as
above described, and is payed round the tube of gutta percha, vulcanized
india-rubber, or vulcanite.
In constructing lightning conductors, to prevent the danger and damage
which occur to the telegraph instruments and operators when the line wires.
are struck by lightning, we take flat slabs of slate, wood, plaster of Paris, or
other non-conducting material, and bore a number of holes through them,
about a quarter of an inch in diameter; the slab is then laid on a flat face plate
of iron, and a short pointed brass pin is dropped into each hole, with its point
resting on the face plate; fluid plaster of Paris is then poured over the whole
to cement the pins in their places, and when set melted lead, solder, or other
metal is poured on the top in such manner as to place the whole.of the pins
in metallic connection; suitable terminals are added for the connection of the
line wires, and the whole is fitted in a wooden frame or box. By these means
the whole of the points of the brass pins are set exactly in the same plane, and
when placed on a perfectly flat metal plate, which is connected with the earth
with an intervening piece of bibulous paper or muslin, they form an efficient
lightning conductor.
Figure 4 is a longitudinal section of a lightning conductor, constructed
according to our Invention. a is an iron or metal plate, placed on its upper
face; b is a wooden cover fitting over the plate a, and containing a slab of
slate c; this slab is perforated with a convenient number of holes (say, twenty-
four), and has brass pins c¹ fitted into it in the following manner:-The slab
is laid on a flat plate, and the pins are dropped into the holes in it, so that
their points rest on the flat plate; plaster of Paris is then run into the holes,
so as partially to fill them and secure the pins ; lead or other suitable metal
is then cast around the pins, so as to connect them all together and to hold
them firmly in their places; the wooden casing is then placed round the slab,
and the binding screw d, which when the apparatusis in use is connected with
the line wire, is fixed to the top of the case, and its stem screwed into the lead
or other metal, which connects the pins. When the lightning conductor is
connected up with the line wire and with the earth, a thin fabric (we have
found silk to be the most suitable) is placed between the plate a and the
slab c.
This arrangement may be modified in the following manner:-A metal

page_text: plate may be employed in place of the slab c, such plate being perforated in a
similar manner, and supported at a short distance above the platea; into the
perforations of the top plate pins are fitted loosely, and when such pins are in
their places their points rest on the fabric placed on the plate a; the upper
plate is furnished with a binding screw for connecting it with the line wire.
Heretofore, in testing the state of the insulation of telegraph wires, it has
been customary to employ two different kinds of galvanometers or detectors,
one wound with fine wire for ordinary use, and another wound with thick
wire for measuring the force of batteries, and called a "quantity" detector.
Now, in constructing a detector according to our Invention, we wind it
with fine wire in the ordinary manner, and in addition we lead a short length
of a few yards of very fine wire from one terminal to the other, so that when
any galvanic current is passed through the instrumenta portion of the current
only goes through the galvanoineter coil of the instrument, and the remainder
and greater portion passes through the short wire, and since the relative pro-
portion of the two quantities always remains constant, the whole quantity
passing is indicated as accurately as if it all passed through thegalvanometer
coil. A switch enables the short wire to be thrown into circuit or out of
circuit at pleasure, and converts the instrument at will either into a "quantity"
detector or an "intensity" detector.
In order to form standard detectors, and to enable the indications of such
instruments to be comparable and be kept constant, a test coil is added to
each instrument; this consists of a reel or coil of exceedingly fine wire, with a
suitable terminal attached to it on the exterior of the instrument,so arranged
that the current may be passed both through this resistance coil and through
the galvanometer coils. If a current from a single cell of a battery be thus
passed through the instrument and its coil,it will be found that down to a very
small limit the indication of the needle will be the same whatever be the size
of the battery plate employed, and this indication being made constant for
every instrument, and recorded on its face, the operator can at any time
verify the correctness of his instrument by trying the effect of one cell of a
battery upon it. Without this fine wire resistance coil the deflection caused
by one cell of a battery varies so greatly with the size of the plates that no
practical use can be made of the indication thus obtained.
Figure 5 is a diagram of a galvanometer arranged according to our Inven-
tion. A, B, represent the two terminals, and C, D, the two coil checks of an
ordinary galvanometer wound with fine wire, such as are commonly used to
measure small quantities of electricity; E represents an ivory knob, working
in a guide, which, when it is pressed down, brings the spring F into contact

page_text: with G, and thus completes an additional circuit between A and B ; His a
resistance coil, composed of two or three feet of fine wire, forming part of this
secondary circuit. When a battery of which we desire to measure the quantity
is connected to A and B,and the knob G is pressed down, the current passes
from A to B by two channels, viz., by A, C, D, B, and by A, G; H, B; and if
the wire A, G, H, B, is only one-hundredth part of the length of the wire
A, C, D, B, then by well-known laws of conduction, ninety-nine-hundredths of
the current will pass through the shorter circuit, and only one-hundredth part
will pass through the principal coils C, D, and the needle of the galvanometer
being acted upon only by one-hundredth part of the whole quantity of the
battery, will have the indication of the current still within its range. I is a
resistancecoil used in testing the galvanometer; it contains sufficient fine wire
to give a resistance equal to 50 miles of line wire, and it is preferable to wind
one half the wire in the opposite direction to the other half to prevent the
maguetic influence affecting the galvanometer needle above. When it is
desired to ascertain if the galvanometer needle is magnetized to the proper
standard degree of strength, a battery of one pair of plates of the kind known
as Daniell's battery, using a saturated solution of sulphate of copper, is con-
nected to the two terminals K and B, so that the current has to pass from K
through the 50 mile resistance coil I to A, and thence through the galvano-
meter coils to B, or vice versa; and the needle is so weighted that with this
resistance it should when properly magnetized bedeflected to an angle of,say,
exactly 25 degrees to the right or left. Now, however large the battery plates
may be, the resistance coil will so limit the passage of current that only a
standard and determinate quantity can flow through them; and on the other
hand, however small they may be down to the limit of half an inch square, they
will still produce as much electricity as the resistance coil can convey, and
will therefore produce the standard deflection of 25 degrees. If the needle of
the galvanometer at any time gives more or less than 25 degrees with one cell
of Daniell's battery, it should be demagnetized or remagnetized until it is
adjusted to the original standard
The auxiliary coils H are also useful for reducing the strength of what is
technically called the "return current" in submarine cables,and thus enabling
their length or the distance of a fault to be determined by a galvanometer,
which would otherwise have been too delicate for the purpose. In order to
render the magnets employed for maguetizing the needles of telegraphic
instruments and detectors more suitable for the purpose, we form them of the
usual horse-shoe form, and at the back or bend of the horse-shoe we hinge the
plates one into another, so that their ends may be opened or separated, and we

page_text: introduce a spring tending at all times to keep them open. We cap the poles
or ends of the magnet with two wrought-iron curved horns, which come into
close contact when the magnet is closed, and the narrow curved horns are of
such a shape as to permit a needle to be magnetized without taking the coil
to pieces.
Figure 6 is a front view, and Figure 6 an edge view, of a magnet con-
structed in the manner we prefer in carrying our Invention into effect. a, a,
are two wrought-iron plates hinged loosely together at a¹, and curved roundat
their lower ends, so as to form the pole pieces of the magnet; b, b, b, b, are
four magnetized plates of steel, two of which are rivetted to each of the
wrought-iron plates a, a; c is a spring, which tends to separate the two limbs
of the magnet, but which is just insufficient to overcome the attractive force,
and to separate the two pole pieces when they have been brought into contact.
In place of constructing a magnet in this manner, the body of the magnet may
be made entirely of magnetized steel, the pole pieces alone being of wrought
iron, or these also may be made of steel if desired. It is known that a magnet
with its armature constantly drawn away by a weight which it can just
support will retain its magnetism unimpaired or even increase its strength,
while under ordinary circuinstances it would lose its maguctism. The spring
above described has a similar effect.
In witness whereof, I, the said Josiah Latimer Clark, have hereunto set
my hand and seal, this Twentieth day of July, in the year of our Lord
One thousand eight hundred and fifty-nine.
JOSIAH LATIMER CLARK. (L.s.)