IMPROVEMENTS IN APPARATUS FOR TESTING TELEGRAPH CONDUCTORS, PART OF THE INVENTION BEING APPLICABLE TO OTHER PURPOSES
Year: 1867

page_text: LETTERS PATENT to Frederick Henry Varley, of 337, Kentish Town
Road, in the County of Middlesex, for the Invention of "IMPROVEMENTS
IN APPARATUS FOR TESTING TELEGRAPH CONDUCTORS, PART OF THE INVENTION
BEING APPLICABLE TO OTHER PURPOSES."
Sealed the 31st December 1867, and dated the 18th September 1867.
PROVISIONAL SPECIFICATION left by the said Frederick Henry Varley
at the Office of the Commissioners of Patents, with his Petition,
on the 18th September 1867.
I, FREDERICK HENRY VARLEY, of 337, Kentish Town Road, in the County
of Middlesex, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN APPARATUS FOR TESTING TELEGRAPH CONDUCTORS, PART OF THE:
INVENTION BEING APPLICABLE TO OTHER PURPOSES," to be as follows:-
Firstly. I suspend ina helix or galvanometer coil with silk or any suitable.
wire or fibre a small magnet carrying a reflecting prism, or I use a plain.
silvered reflecting surface fixed to a small magnet. A small telescope at a
horizontal angle of 45° is placed with its object glass as close to the prism or
reflecting surface as practical, so that any object whose image after reflection
is coincident with the optic axis of the telescope is rendered visible to the eye
through the eye piece of the telescope aforesaid. A divided scale, or single
arrow, or index is fixed at any practical distance in view of the mirror, so
that a small motion of the mirror will make the divided scale, or arrow, or
index appear to pass before the eye.

page_text: Secondly. Where I require extreme sensitiveness I use an exceedingly
small plane mirror, sometimes not more than a of an inch in diameter;
but where practical I prefer one of of an inch in diameter. This delicate
mirror carrying a light magnet is placed before the object glass of a micro-
scope, so that a fine line of light or a small microscopic photograph of a scale
can be reflected by this small mirror in a line with the optic axis of the
microscope. If a line of light be used I place in the focus of the eye piece a
photographed scale, or if the microscopic photograph be reflected by the
mirror I use an ordinary micrometer eye piece, or place a single cobweb or
wire in focus of the eye lens.
Thirdly. I suspend a small hollow cylinder vertically, having on one side a
thin vertical slit, and carrying a small lens in focus of the slit from the
opposite side of the cylinder, so that light passing through the slit aforesaid
be thrown by the small lens and rendered visible by an eye piece in the
manner of an ordinary microscope; fixed to this suspended cylinder is a small
magnet. I sometimes use a small indicating wire in focus of the lens afore-
said, in which case the lens is carried by au arm. Sometimes I employ a lens
detached from the moveable arm, in which case the lens or object glass of
the microscope is placed near to the suspension filament so as to be out of
focus with it, and in focus with the moveable indicating wire. This wire
when seen through the eye piece of microscope appears as a black bar
bisecting the field of view. Any motion of the indicator which may be part of
the magnet itself is seen by the black bar traversing across the field of view
and bisecting any portion of the scale placed in the focus of the eye piece
accordingly as the indicator moves to the right or left.
Fourthly. I construct an improved arrangement of resistance coils, by
which I greatly increase their efficiency. They are so constructed to enable
them to multiply standards of resistance any required number of times in the
following manner: -I adjust two coils of German silver or any suitable wire
covered with silk wrapped in the usual manner in the following proportions:-
For a hundred multiple, first I make a coil equal to 1.01 ohmads of resistance
and a second of 99 ohmads or British Association units of resistance. The
wire ends of each coil are connected to three metal tablets or terminals
arranged in a line and fixed on ebonite or any suitable insulating substance,
so that one end of each coil is connected to the outer tablet or terminal, the
other two ends are joined together at the middle tablet or terminal, so that
when a current of electricity is made to pass through by one of the outer
terminals through the two coils to the other outer terminal it shall experience
a resistance equal to 100.01 ohmads. I now connect between the first

page_text: terminal connected with small coil (1·01 ohmads) and the middle terminal
the two outer terminals of a similar standard. By looping a second standard
a hundredth part of the current flowing through the first coil is shunted off.
The resistance of the first standard is reduced from 100-01 to 100 ohmads,
01 of the current passing through the looped circuit; if I loop a third standard
on the second in a similar manner I shall have 01 of current flowing through
the standard No. 2, consequently 0001 of the current flowing through the
first (or, in other words, one ten-thousandth). Every time I loop on a
standard I get one-hundredth of the force flowing through the preceding, that
is, by using standards of the proportion above mentioned. On looping on one
standard the force flowing through loop would be equal to a resistance of one
hundred multiplied by one hundred; if a second be looped the force flowing
through second loop will be equal to 100 multiplied by 10,000; if a third
loop is used the current flowing through will be equal to 100 multiplied
by 1,000,000. By this means an effect equivalent to enormous resistances can
be obtained in the most ready manner when using the force flowing through
the standards or multiples herein-before described. I prefer wrapping the
hollow coils of galvanometer herein-before mentioned with two equal lengths
of wire wrapped round an equal number of times, and so connected that
an equal amount of electric force travelling simultaneously through each
wire will not cause any deflection of the magnet, in other words, I use the
ordinary differential mode of winding. For sake of distinction I term one
wire the test coil of the galvanometer, the other the line coil.. The test
coil is looped between the first and middle terminal or tablet of standard. One
pole of a battery is connected to one end of line coil and to one end of the
standard. The current divides itself between the line coil of galvanometer
and standard and flows through both, when the circuit is completed by con-
necting the remote end of line coil and the remote end of standard to the
opposite pole of battery. The test coil receives a portion of the current
flowing through the standard, while the line coil has the full force of the
battery passing through it. If the test coil be so proportioned as to receive one-
hundredth of the current flowing through standard, whatever resistance the
standard may be it will require the line circuit to be one hundred times
greater than the resistance of standard to balance the needle; by this means
any telegraph line or circuit can be measured, through the electrical resistance
to greater than that of the standard. The test coil may be joined to the
second, third, or fourth looped standard, and will receive a current propor-
tionately weaker accordingly as it is placed. I sometimes make the standard
of more than two coils so arranged that by removing the connections any

page_text: multiple can be obtained according to the position of loop or test coil of
galvanometer in a precisely analagous manner to that mode herein-before
described. In testing the insulation of submerged or other insulated lines
the battery current generally flows through the standard and into the line or
cable to be tested, and is measured by means of the arrangement known as
the Wheatstone bridge, or balance, or its various modifications, or by the
differential method. When the potential balance is used, and the standards of
resistance are not equal to the amount of resistance opposed by the insulated
'cable, it is usual to shorten or lengthen the arms of the balance until the ratio
of the resistance of the short arm is to the longer arm as the length of a
known standard is to that of the cable. This is measured by a very sensitive
galvanometer which indicates by the needle remaining stationary when the
relationship between the resistance of the two arms of the balance and
standard and cable is complete, deflecting to right or left when the
resistance of the arms are not correctly proportioned. When such an
arrangement is used the galvanometer is put into circuit by means of a key
which when depressed connects one of the two ends of the galvanometer coil
to the slide of the electric balance, the other end is connected between the
standard and insulated copper wire of cable. On depressing the key the
electric potential of balance is measured against that of the cable. The
position of the slide regulates the proportion of the two arms of the balance.
While the key remains open the current flows equally through the balance
and into the cable, but on keeping the key depressed the battery current
finds two channels to the insulated wire, one through the standard coil and
the other through one arm of the balance itself by means of the galvanometer
which is put in circuit, and consequently the insulated wire receives a higher
charge than that of the balance, and thereby recording a fallacious amount of
insulation.
To avoid the defect above described I construct a potential measurer as
follows: Two pairs of circular metal plates or directors fixed upon insulating
pillars with the metal plates of each pair placed vertically and held about
one-eighth of an inch apart by fixing the pillars in a metal or wood stand.
One pair of insulated plates or directors is placed about four inches from the
other with the spaces between the directors in a line; in the centre between
these two pairs of directors is placed a fifth insulating pillar supporting a
metal frame and carrying a light metal arm which is suspended from the
frame by silk or other suitable fibre. Attached to the centre of the metal
arm is a mirror, prism, or indicator, as herein-before described. Two moveable
insulated plates or potential testers are fixed on a slide actuated by a screw,

page_text: and are placed on each side of the insulated frame, so that by turning the
screw one plate approaches to the centre while the other recedes, and vice
versa. When using the apparatus I charge the four directors with positive
and negative electricity in such a manner that if I induce in the metal
frame a charge of positive electricity the suspended wire will be deflected
towards the right, and with a negative charge to the left, or vice versa. I
connect the two poles of a battery through a series of resistance coils generally
consisting of ten coils of 1000 ohmads each and one coil of 90,000. The
end of each coil is brought up to a tablet or terminal. I generally join the
negative pole of the battery to the end terminal of the series which is
connected to the large coil, and the negative current of the battery divides
itself with the insulated wire of the cable by passing through a large
resistance coil. The negative current likewise flows into the insulated wire
of the cable by passing through a large resistance generally of a 100,000
ohmads resistance; the other pole of the battery is joined to the end
terminal which is connected with the 1000 ohmad coils and also to earth.
One of the potential testing plates is joined to the insulated conductor or
cable, and the other testing plate is generally connected to the fourth or fifth
terminal from the positive pole of battery. The plate connected to cable will
receive negative charge whilst the other connected to the fourth terminal
will be positive; if then the two plates are placed at equal distances from
the indicating frame, and the negative charge of cable equals the positive
electric charge derived through the fourth or fifth resistance coil of 1000
ohmads each, no deflection of indicator takes place, but if one of the testing
plates be more highly charged than the other the indicator will move, it
is necessary then to turn the screw until the more highly charged plate
recedes and the other approaches sufficiently to make the neutral portion
between the two plates coincident with the indicating frame, when the
indicator again returns to zero. The milled head of the screw is divided so
that the amount of motion can be recorded.
The different amounts of positive and negative electricity are determined
by the position of the testing plates. When I want the instrument to be very
sensitive I charge the directors with static electricity; this is readily done
by a small hand electrical machine which I construct in the following manner
on the principle invented by the late Cornelius John Varley, with some
modification, so that it can be manufactured at the minimum of cost. It
consists as follows: - A glass tube or ebonite rod is fixed in a handle with
any suitable cement and forms the electric to be excited. A piece of
wood or any suitable material about three inches long is grooved lengthwise

page_text: with two semicircular grooves, into one of these grooves I fix the rubber
containing the amalgum or other electric excitant. I wrap round the
grooved wood a piece of leather or cloth, so that it forms with the groove
on one side a cylindrical chamber to hold the condenser or electric accumu-
lator and a flap which when machine is used can be wrapped round the
electric and form a continuation of the rubber. A ring conductor is con-
nected to the condenser and made to go over the electric so that as the
rubber moved to and fro along the electric it receives the charge from the
excited electric and conveys a charge of electricity into the condenser.
I also employ when testing a cable by the ordinary charge and discharge
test an improved regulator which charges and discharges the cable with
electricity at any regular desired intervals of time. An ordinary com-
pensating pendulum is swung between two smaller pendulums which are
held in a position ready to descend by traps placed on each side of the large
pendulum within the arc of oscillation, so that as the large pendulum bar is
swang against one of the traps the small pendulum descends and by its weight
against the large pendulum gives the needle impulse, causing it to swing to
the second trap, when the second small pendulum is liberated and falls in
the reverse direction to the first, and as long as the small pendulums are
raised into their traps the large pendulum is kept continuously swinging.
The large pendulum rod carries a contact pin so placed that when the large
pendulum is in the centre of its oscillation it shall make contact with a
delicate spring, when an electric current flows from the suspension spring of
large pendulum through pendulum bar to contact spring, whence it is made
to flow round the coils of electro-magnets to attract armatures fixed upon
the small pendulums and raises them into the traps aforesaid. The small
pendulums are carefully adjusted and compensated for the effects of change
in temperature and swing at a rate slightly quicker than the large pendulum.
When the large pendulum is in the centre of its oscillation it not only actuates
the raising of the small pendulums but moves by a step-by-step motion a train
of wheels which make and break contact of another electric circuit at any
intervals of time by raising or depressing light levers carried on the edge of
the wheel or by any other suitable contrivance for closing or opening an electric
circuit. The pendulum above described may be employed for self-registering
electrical tests, and as it can be kept continuously swinging when once set in
motion by electricity actuating the raising of small pendulums as aforesaid.
In cases where needful I place the pendulum apparatus in an air-tightcase,
which can be exhausted to avoid any variation in the viscosity of air, which
would affect the rate of oscillation of the pendulum aforesaid. In order to

page_text: exhaust this pendulum case aforesaid with certainty and facility I construct
a new mercurial air pump which reduces the wear and tear of the valves to
nil, and can be depended upon for constancy in its operation, as the valves
are worked mechanically by a rising and falling column of: mercury. This
with the fewness of parts renders it unliable to put the pump out of working
order in course of using. It is made as follows:-Two cylinders or tubes
made of any material impervious to air and not affected by mercury, one almost
fitting the other, the inner tube being about 48 inches long, and the outer one
about. 50 inches. The inner tube is held vertically, and affixed to the upper
end of the tube is the valve piece made of any material impervious to air and
not affected by mercury. The valve piece is of a cylindrical form, having a
smaller cylinder that goes inside the inner tube about five-eighths of an inch,
and terminates at the lower end with a conical or convex face. A hole is
drilled through the centre of the valve piece to admit of a triangular sided
wire passing through it freely. This wire carries a conical or concave
cup which when pressed up against the small cylinder shall fit exactly and
form the exhaust valve. The lower part of the cup aforesaid terminates with
a rod carrying a sliding weight, having a limited amount of motion, so that
when not floated by mercury it shall always fall and keep valve open. Between
the small cylinder and interior of tube a hole is drilled about an eighth of an
inch in diameter,passing through the valve piece parallel to the exhaust valve
hole. This small hole is drilled downwards from the top of valve piece with a
larger drill about three-eighths of an inch in diameter to about half an inch
deep, forming a conical shoulder to the small hole. A pin with a conical
head is let through the small hole, the head of which rests upon the shoulder
aforesaid and forms the outlet valve. The outer tube or cylinder about 50
inches long is closed at its lower extremity, and forms a cylindrical holder for
mercury. When pump is put in use the outer cylinder is held up against the
inner one; the outlet valve is removed, and mercury is poured through the
hole until the inner tube and the space between the inner and outer tubes are
completely filled with mercury, when the outlet valve is again put into its
place; the exhaust valve hole is connected by a tube to the air pump plate,
and with a counecting pipe joined on to the pendulum case aforesaid. Upon
lowering the outer tube by means of a rack and pinion motion, or by a band
passing over a pulley, the mercury falls in the inner tube or cylinder, leaving
the inner space to be filled with air contained in pendulum case; upon raising
the outer cylinder the mercury rises and floats up the exhaust valve to close the
aperture, whilst the air contained in the space is liberated by the outlet valve;
the outer cylinder is raised and lowered until a complete or sufficient vacuum

page_text: is obtained. When the vacuum becomes more and more complete the outer
cylinder requires lowering much more than at first starting,and as it approaches
nearer and nearer to a Torricillian vacuum the outer cylinder must be lowered
sufficiently until the mercury column which will remain in the inner tube at
the barometric heighth shall leave a space between the valves and upper surface
of mercury. The exhaust valve remains open, and allows the residue of air
to flow into the Torricillian vacuum, from which it is again driven out by
raising the outer chamber aforesaid. This process can be repeated until a
complete Torricillian vacuum be obtained in the pendulum case aforesaid.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Frederick Henry Varley in the Great Seal Patent
Office on the 9th March 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERICK
HENRY VARLEY, of 337, Kentish Town Road, in the County of Middlesex,
Telegraphic Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
of our Lord
Patent, bearing date the Seventeenth day of September, in the year
One thousand eight hundred and sixty-seven, in the thirty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Frederick Henry Varley, Her special licence that I, the said Frederick
Henry Varley, my executors, administrators, and assigns, or such others as I,
the said Frederick Henry Varley, 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, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN APPARATUS FOR TESTING TELEGRAPH CONDUCTORS, PART OF
THE INVENTION BEING APPLICABLE TO OTHER PURPOSES," upon the condition
(amongst others) that I, the said Frederick Henry Varley, 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 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 Frederick Henry Varley, do hereby

page_text: declare the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement :-
For the sake of distinctness I have divided the description of the said.
Invention into several parts, that is to say,
Firstly. I suspend in a helix or galvanometer coil with silk or any suitable
fibre or wire a small magnet carrying a reflecting prism, shewn at R, Fig. 1,
or I use a plane silvered or suitable reflecting surface fixed to a magnet, so
that a small telescope T placed at a horizontal angle of about 45°, with its
object glass O placed as close to the prism or reflecting surface as practicable
in order that any object whose image after reflection is coincident with the
optic axis of the telescope is rendered visible to the eye through eye piece V
of telescope aforesaid. A divided scale S or single index or arrow is fixed at
any practical distance in viewof the prism Ror mirror, so that a small motion
of the prism R.or mirror will make the divided scale S, or arrow, or index
appear to pass before the eye. This prism or plane mirror is used in con-
junction with the telescope T to measure the amount of deflection to which
the attached magnet n, s, may be subjected by the passage of electric currents
round the helix.or galvanometer coil C. The apparent proper motion of magnet
is doubled by the reflection of prism R or mirror. The motion of image of
scale S, or arrow, or index is increased as much as desired by varying the
power of the telescope T.
T6
Secondly, Fig. 2. When I require greater sensitiveness I use an exceed-
of an inch in
ingly small plane mirror, sometimes not more than a
diameter; but where practicable one of of an inch or larger, as circum-
stances will admit. This delicate mirror carrying a light magnet, shewn
at n, s, is placed before the object glass of a microscope, so that a fine line of
light, or a small microscopic photograph of a scale, or an index, or an arrow
can be reflected by the mirror in a line with the optic axis M of microscope.
If a line of light be used I place in the focus, of eye piece V, Fig. 2, a photo-
graphed scale; or if the microscopic photograph be reflected by the mirror I
use an ordinary micrometer eye piece, or place a single cobweb or wire in
focus of the eye lens e, l, as shewn at A, Fig. 2. p represents the bracket
holding a microscopic photograph; l, a lens for concentrating the light of
the lamp E. I sometimes place the mirror or reflecting surface at an angle
about 90° with the magnet n s, in which case the photographed scale p
and lamp Bare placed at the opposite side of the galvanometer coil C; but I
prefer using where practicable the arrangement shewn in Fig. 2.
Thirdly, Fig. 3. I suspend a small hollow cylinder 1, s, vertically, having

page_text: on one side a thin vertical slit s, and carrying a small lens lin focus with the
slit from the opposite side of cylinder, so that the light passing through
the slit aforesaid be thrown by the small lens and rendered visible in the
manner of an ordinary microscope. Fixed to this suspended cylinder is a
small magnet n, s, which gives motion to the cylinder carrying the slit and
lens aforesaid on the passage of an electric current round the coil C. The
cylinder being suspended from its axis of rotation gives very steady and
uniform deflections, having no asperities to catch the air and being moved
on its centre of gravity.
The cylinder is represented at A and B, Fig. 4, enlarged about four times,
A being a bird's-eye view shewing magnet n, s, and lens and slit s; B is a
side view of the same cylinder. When it is desirable to dispense with the
encumbered weight of cylinder I use an arm attached to the magnet of the
form shewn at A and B, Fig. 5. A is a bird's-eye view; B is a side view of
this arrangement. I prefer using the small lens attached to the indicating
arm, Fig. 5, when the angular deflection of the magnet is great, the lens
moving with the indicator when once adjusted for least spherical aberration
will always remain so and become equivalent to a large aperture. In many
cases it is desirable to get rid of the encumbered weight of prism, mirror,
cylinder, or lens aforesaid to reduce the retardation due to inertia, and have
as nearly as possible only the weight of the magnet itself, which may be
of exceeding delicacy.
Fig. 6 shews a bird's-eye view; Fig. 7, a side view. w, magnet; I,indicating
arm attached to magnet w suspended by any suitable filament, thread, or wire.
Fig. 7 shews the form of indicating arm generally employed. The object
glass of microscope O is focussed to the further arm of the indicator shewn
at I; this wire when seen through the eye piece of microscope appears as a
black bar bisecting the field of view. Any motion of the indicator is seen
by a black bar traversing across the field of view and bisecting any portion
of the scale placed in the focus of the eye piece, by which the deflection
can be measured.
Fig. 8 represents the arrangement employed when the indicating arm is
dispensed with, and the weight of the magnet is the only inertia to be
overcome by the feeble currents sent round the coil C, in which case the
magnet is generally made of an
T
form; the hollow coil is generally
the form as shewn in Fig. 8. A suitable reflecting surface A is placed at
such an angle that the image of the magnet can be reflected into the object
glass of microscope, which I prefer focussing to the further arm of the
shaped magnet marked n; then end of the magnet is then seen

page_text: to traverse the field of view in the same manner as the indicating arm before
mentioned on deflection of the magnet. I sometimes remove the eye piece
of microscope aforesaid, when the image can be focused by the object glass
or lens on a screen in a similar manner to the gas microscope or magic
lantern. I then employ a condenser for collecting or concentrating the rays
of light from an electric lamp or any suitable source of light which thrown
upon a screen gives a field of white light, upon which can be placed one or
more divided scales which are rendered conspicuous by the amount of
illumination. The indicator or magnet appears as a moveable black line
crossing the field of illumination, as shewn at S, Fig. 9.
Thirdly, I construct an improved arrangement of resistance coils shewn at
Fig. 10, by which I greatly improve their efficiency; they are contrived to
multiply standards of resistance any required number of times, that is to say, I
adjust two coils of German silver orany suitable wire covered with an insulating
medium or fibre wrapped in the usual manner in the following proportions:―
For a hundred multiple first I make a coil = 1.01 ohmads of resistance, as
shewn at a, Fig. 10, and a second of 99 ohmads or British Association units,
shewn at b; the wire ends of each coil are connected to the tablets or
terminals A, B, or C, and fixed upon any suitable insulating material, so that
one end of each coil a and b is connected to the terminals A or C, and the
two other ends are connected at B, so that any current of electricity from
P and N which is made to pass from A to C, or vice versa, shall experience
the resistance of a+b=100-01 ohmads. I connect between the terminals A
and B the two outer terminals A¹ and C¹ of a similar arrangement or standard
shewn in Drawing, by thus looping on a second standard a hundredth part of
the force flowing through coil a is shunted off. The resistance of the first
standard is reduced from 100-01 to 100 ohmads, '01 of the current passing
through the looped circuits A' and C¹. If I loop a third standard on the
terminals A¹ and B' of the second standard in a similar manner 01 of the
currents flowing through the standards from. A' to C¹ will pass through A² to
C2, consequently 0001 of the current flowing through A and C of the first
standard, or, in other words, one ten-thousandth. For every standard I loop
on I obtain roo part of the force flowing through the preceding one, that is,
by using standards of the proportion above mentioned, that is to say, the
electro-motive force flowing through A to C= 100 force flowing from A¹ to C¹
=100 x 100=10,000. The force flowing from A2 to C2=10,000 × 100=
1,000,000, by this means an effect equivalent to enormous resistances can be
obtained in the most ready manner. To measure the force flowing through
the looped standards I generally employ the arrangement known as the

page_text: differential galvanometer, which consists of two insulated wires wrapped round
a hollow coil frame an equal number of times, and so connected that when an
equal amount of electric force flows through each wire no deflection of the
indicating magnet takes place. For sake of distinction I term one of the
wires the test coil of the galvonometer, the ends of which are brought to the
terminals T and T¹, the other the line coil brought to terminals L and 1.
The test coil is looped between terminals A and B, or A' and B', or A2 and B2,
of standards according to multiple required. One pole of a battery P is
connected to one end of line coil Land to the terminal A of standard flowing
through both when the circuit is completed by connecting the remote end of
line coil L and the C terminal of standard with the N pole of battery. The
test coil T receives a shunted portion of the current flowing through the
standards, while the line coil has nearly the full force of the battery passing
through it. If the test coil be so proportioned and looped so as to receive
one hundredth of the current flowing through the standard whatever
resistance the standard may be, it will require the line circuit to be one
hundred times greater than the resistance of standard to balance the needle.
By this means any telegraph line or circuit can be measured, though the
electrical resistance be greater than that of the standard; in a precisely
analogous manner any multiple can be obtained by proportioning the
standards and looped circuits. Sometimes I employ a standard comprising
a series of coils ranging from a given unit to any desired amount, by which
the value of electric current flowing through looped circuit can be altered
as the resistance is increased or diminished by placing the multiples above
described at the end of a series of resistances, or by placing them between
one or more series of ordinary resistance coils.
In testing the insulation of submerged or other insulated wires the battery
current generally flows through the standard and into the submerged or other
insulated wire, and is measured by an arrangement known as the Wheatstone's
bridge or potential balance. When the potential balance is used, and the
standards of resistance are not equal to the amount of resistance imposed by
the insulated wire, it is usual to adjust the arms of the balance so that the
ratio of the resistance between the short arm and the longer one is the same
as a known standard is to that of the insulated wire; this is determined by
means of a galvanometer inserted between the slide of balance and insulated
wire or cable by means of a key; when the key is depressed the electric
potential of balance is measured against that of the insulated wire or cable.
The position of the slide determines the proportion of the two arms of the
balance, while the key remains open the current flows through the arms of

page_text: the balance and into the cable, but on keeping the key depressed to measure
the electric potential of cable against the potential of slide the value of the
known standard becomes altered because the electric current finds an extra
channel through the short arm of balance and galvanometer coil to the
insulated wire of cable. The cable thereby receives a different potential and
records a slight error.
Fourthly. To avoid the above error I construct an instrument which I term
a potential measurer, shewn in Figs. 11, 12, and 13. It is as follows:-Two
pairs of metal plates or directors D, DI, 7, d, are placed vertically with the
space of about of an inch between D or D', and between d, d', supported on
ebonite pillars I, I, I, I, Fig. 11, or on any suitable dielectric. Placed
between the two pairs of director plates is an insulating support with a
conducting frame shewn at F, from which is suspended a light metallic arm A
by silk or any suitable fibre (attached to the centre of metallic arm A is a
mirror prism or indicator employed with the telescope or microscope in such a
manner as to render any slight motion of the arm A apparent). This is
omitted in Drawing to render the description of the working part of the
instrument more clear. Two moveable insulated plates, which I term
potential testers B, B', are fixed upon a slide C actuated by a screw G,
Figs. 11 and 12, or any other means to give motion to the slide C which carries
the two insulated plates B, B', so that on moving the slide C one of the
potential testers B or B approaches towards the frame F, while the other
recedes, or vice versa. When using the apparatus I charge the four director
plates in the following mauner:-D, d, are joined together by a conductor
shewn in Figs. 11 and 12, D and d by another separate conductor, so that the
plates and d can be charged with the same electricity. I charge the
opposite plates D' and d¹,with the opposite kind of electricity, or I sometimes
charge only one pair with electricity and put the opposite pair in connection
with the earth in such a manner that any force induced in the moveable
arm A by the inductive action of the plates B and B' exerted upon the frame
F shall cause the arm A to be moved. I connect the poles of a battery P
and N, Fig. 13, through a series of resistances generally consisting of 10
coils of 1000 ohmads each and one coil of 90,000 ohmads; the end of each
coil is connected to a tablet or terminal in the manner shewn in Drawing. I
generally join the negative pole of battery to the end terminal of the series S
which is connected to the larger coil of 90,000 ohmads, the same pole is also
connected to the insulated wire of cable through the large resistance R. The
other pole of battery P is joined to the end terminal s which is connected to
earth. One of the potential testing plates B' is joined to the insulated wiro

page_text: of cable W, Fig. 13. The other testing plate B is joined to any of the
intermediate terminals or tablets of the series S to s according to the potential
required. The plate B¹ will have the negative electric potential of the insu-
lated wire of cable, whilst the plate B connected with tablet of series will
have a positive electric potential. The valve of potential of plate B is
regulated by its position on the series S, s, whilst the value of the plate B' is
dependent on the amount of insulation of the insulated wire of cable. When
the plates thus connected are placed at equal distances from the frame F, and
the electric potential of cable equals the positive electric potential derived
from the series S, s, no deflection of the arm A takes place, but when one of
the testing plates is more highly charged than the other the indicator moves
towards D' and d', or D and d; it is necessary then to move the slide C until
the more highly charged plate recedes from the frame F and the opposite
plate approaches sufficiently to make the inductive action of one equal the
inductive action of the other. To measure the amount of motion I have on
the slide C a divided scale which records the proportionate difference between
the potentials of the testing plates. In the potential measurer above
described I employ induction to determine differentially the valve of electric
potentials, and thus remove the error due to the conduction of galvanometer.
Fifthly. I generally keep the director plates D, D¹, d, d³, charged by
connecting them with the poles of a galvanic battery,but when the instrument
is required of greater sensitiveness I charge the director plates D, D¹,
and d, d', with static electricity, this is readily done by a small hand electrical
machine, which 1 construct in the following manner on the principle invented
by my late brother.Cornelius John Varley, with very essential modifications so
that it can be manufactured at the minimum of cost. It consists as follows:-
A glass tube,or ebonite rod, or anysuitable electric substance A, Fig. 14, fixed
on a handle, or the handle may be a portion of the electric itself, a block or
piece of wood, or any suitable material is grooved lengthwise, as shewn
in Fig. 15 at V and W, or shaped in any convenient form; on one side I fix
the rubber or exciting cushion R covered with amalgam or other suitable
electric excitents. I wrap round the wood a piece of leather, cloth, or any
suitable material so as to form a receptacle for the condenser or electric
accumulator (or the receptacle can be made in the block itself) and a flap to
surround the electric A to increase, if desired, the exciting surface of the
cushion. A ring conductor C is connected to the condenser B and made to go
over the electric, so that as the rubber R is moved to and fro along the
electric A the conductor C receives a charge from the excited electric and
conveys it to the condenser B made of any dielectric coated in the form of a

page_text: Leyden jar, or consisting of insulated inductive surfaces, one of which is con-
nected to the ring C, the other connected to the rubber or to a metallic cord
or chain F. On briskly rubbing the electric between the rubber and flap R¹
a considerable charge can be obtained, which is conveyed to the condenser
placed alongside the electric. I generally prefer putting the condenser parallel
with the rod of the electric, as it is the most convenient position, but the con-
denser may be fixed to the rubber block or holder at any desired angle. In
the above arrangement the condenser only receives its charge when the electric
is moving in the direction from the rubber towards the ring; this I term the
single action of the machine; but when I want to utilize the return motion of
moving electric I place a rubber on each side of the condenser ring, or I place
two or more condenser rings at each end of the rubber, shewn in Fig. 16, by
which I accumulate a greater charge in the same period of time. When the
condenser is charged I connect the cord F, Fig. 14, to D' of Figs. 11, 12, and
13, and ring conductor C, Fig. 14, to D of Figs. 11, 12, and 13; a statical
charge is then cominunicated to the director plates, the potential of which
may be varied by charging the condenser to any desired degree of electric.
force. After charging the director plates aforesaid the condenser can be
discharged by touching the condenser ring with the end of metallic cord F,
when an electric spark will ensue and the charged surfaces of the condenser
will return to their normal condition.
Sixthly. I also employ, when testing a cable by the method known as the
ordinary charge and discharge test, an improved regulator, Fig. 17, to charge
and discharge a cable with electricity at any regular desired intervals of time.
It consists of the following parts:-A, a compensated pendulum suspended
from G; B and C, two small pendulums or accelerators pivotted on frame S
at b and c; D and E, two metal arms or traps pivoted at d and e, with
counterpoise weights W to put the arms of traps in position ready for locking
the small pendulums B and C; H, electro-magnet to attract the armatures
K and L, which raise when attracted the pendulums B and C into their
traps, contact piece on large pendulum bar; F, contact spring in con-
nection with one pole of battery; M, a compound terminal with the upper
piece m in connection with one end of the wire of the electro-magnet H; the
other end of wire is connected with G; r, r, two counterpoises to regulate the
rate of the oscillations of small pendulums B and C. When the pendulum A
is swung against the trap D the small pendulum B is liberated and descends
with the pendulum A until it arrives at the centre of its oscillation, when the
electric circuit is completed by contact of fwith F,and the small pendulum B

page_text: is raised by the electro-magnet H into the trap D; the large pendulum A
swings on until it liberates the pendulum C, which in a like manner lescend
with the large pendulum until it arrives at the centre of its oscillation, when
the pendulum C is in a like manner raised into its trap E, giving a regular
to-and-fro impulse to the large pendulum. In this manner a reciprocal impulse
is maintained by gravitation of the small pendulum B and C. The current
which flows on completion of the circuit by contact of f with F not only
actuates the raising of small pendulums, but moves by any suitable magnetic
arrangement with a step-by-step motion a train of wheels which make and
break contact of another electric circuit at any required interval of time by
raising or depressing light levers carried on the edge of the wheel, or by any
other suitable contrivance for closing and opening: an electric circuit to charge
and discharge the cable. The pendulum above described may be employed
for self-registering electrical tests, and as it can be kept continuously swinging
when once set in motion by electricity actuating the raising of small pendulums
as aforesaid.
Seventhly. In cases where needful I place the pendulum apparatus in an
air-tight case which can be exhausted to avoid any variation in the viscosity
of air which would affect the rate of oscillation of the pendulum aforesaid.
In order to exhaust the pendulum case aforesaid with certainty and facility
I construct a new mercurial air pump, which reduces the wear and tear of
valves to nil, and can be depended upon for constancy in its operation, as the
valves are worked mechanically by a rising and falling column of mercury;
this with the fewness of parts renders it unliable to put the pump out of
working order in course of using. It is made as follows:-Two cylinders or
tubes, Figs. 18 and 19, A and B, made of any material impervious to air
and not affected by mercury, one almost fitting the other; the inner tube B
being about 48 inches long, the outer tube about 50 inches in length. The
inner tube B is held vertically, and affixed to the upper end of the tube is a
valve piece C made of any material impervious to air and not affected by
mercury. The valve piece is of a cylindrical form, having a small cylinder D
that goes inside the inner tube B about ths of an inch, and terminates at the
lower end with a conical or convex face. A hole is drilled through the centre
of valve piece to admit of a wire passing through it freely. This wire E carries
a conical or concave cup F, when pressed up against the cone end of small
cylinder D shall fit it exactly, and form the exhaust valve. On the wire E is a
sliding weight G having a limited motion, so that when not floated by mercury
i shall always fall and keep the valve open by. hanging from the stop H

page_text: Between the small cylinder D and the interior of tube B a hole is drilled
about th of an inch in diameter, passing through the valve piece C parallel
to the exhaust valve. This small hole J is drilled downwards from top of
valve piece with a large drill about ths of an inch in diameter to about a
half inch deep, shewn at K, forming a conical shoulder to the small hole.
A pin with a conical head is let through the small hole, the head of which
rests upon the shoulder aforesaid and forms the outlet valve. The outer tube
or cylinder A is closed at its lower extremity and forms a cylindrical holder
for mercury. When the pump is put in use the outer cylinder A is held up
against the inner one B; the outlet valve L is removed, and mercury is
poured through the hole J, until the inner tube and the space between the
inner and outer tube are completely filled with mercury, then the outlet
valve pin Lis again put into its place J. The exhaust valve hole is connected
by a tap N to the air pump plate O, and with a connecting pipe joined to the
pendulum case at P. By lowering the outer cylinder A the mercury falls in
the inner tube B, leaving the inner space Q to be filled with air contained
in pendulum case. Upon raising the outer cylinder the mercury rises and
floats the exhaust valve F, which closes the aperture D, whilst the air
contained in the space Q is liberated by the outlet valve L. The outer
cylinder A is raised and lowered until a complete or sufficient vacuum is
obtained:
In reference to my Invention herein-before described I claim the use of
telescope in conjunction with a reflecting surface applied to galvanometer, as
described in the first part of my Invention.
Secondly. I claim the use of microscope in conjunction with reflecting
surfaces with moveable indicating arms, with prism, and with microscopical
photographs applied to galvanometers, as described.
Thirdly. I claim the arrangement of resistances for multiplying standards
of resistance, as described.
Fourthly. I claim the potential measurer, as described.
Fifthly. I claim the construction of the apparatus for charging the director
plates with statical electricity.
Sixthly. I claim the general arrangement of regulator described. The use
of electricity to raise small auxiliary pendulums to fall by gravity to give
impulses to large pendulum, the use of counterpoises to regulate the rate
of fall of the small pendulums. The use of counterpoises to raise the traps
into position; also the mode of liberating the small pendulums.
Seventhly. I claim the general arrangement of mercurial air pump described,

page_text: and the use of two or more cylinders to effect the rise and fall of a column
of mercury for the purpose of exhaustion.
In witness whereof, I, the said Frederick Henry' Varley, have hereunto
set my hand and seal, this the Ninth day of March, in the year of
our Lord One thousand eight hundred and sixty-eight.
FREDERICK HENRY VARLEY. (L.S.)