CONSTRUCTION AND WORKING OF ELECTRICAL APPARATUS FOR TAKING THE READINGS OF SCIENTIFIC INSTRUMENTS DISTANCE to be as follows
Year: 1884

page_text: We HENRY BLECKLY BOURNE Electrician and HENRY RICHARD Fox BOURNE
Gentleman, both of 8 Queen Anne's Grove, Bedford Park, London, do hereby declare
the nature of our said invention for "CONSTRUCTION AND WORKING OF ELECTRICAL
APPARATUS FOR TAKING THE READINGS OF SCIENTIFIC INSTRUMENTS
DISTANCE to be as follows:―
FROM
A
The object of our invention is to provide a simple means of reading various
scientific instruments such as Barometers, Thermometers etc at a place remote from
the said instrument.
For this purpose we arrange a battery or other generator of electricity, sundry
wires of suitable material, and a galvanometer or other instrument for detecting
electrical currents in the manner shown in the accompanying diagram.
When the wires A B, C D, A C, B D, are connected together as shown together
with the battery P and the galvanometer G and G E, GF, then (by the principle
of the "Wheatstone's Bridge") if either of the points E or F are moved, so that
there is no difference of potential between the points E and F, the lengths of A. E,
E B, C F, F D will bear a certain ratio to one another whence the position of the
points E and F may be calculated. And if AB represent the scale of the instrument
the position of E will represent the position of the index on the said scale.
The position of the battery and galvanometer are interchangeable.
In order to more clearly indicate the method of applying the above principle to
our invention, let us suppose we desire to indicate the quantity of water in a
cistern at a distance from the same. In this case we provide a suitable float which
by rising and falling with variations in the level of the water will indicate the
quantity thereof. Now in order that the position of the said float may be
ascertained at a place remote from the same we fix in a convenient position a wire
or strip preferably of platinum or other inoxidizable material having a high
electrical resistance corresponding to A B, in the accompanying diagram. At the
point E we provide a sliding contact which is connected by suitable mechanical
contrivances with the above mentioned float in such manner that the said float in
moving will also move the sliding contact.
The sliding contact is at E on the diagram. It will thus be seen that the
position of E on the wire A, B, will afford an indication of the level of the water

page_text: in the cistern. The wire C, D, and the current detector G are located at the above
mentioned remote place the battery P being in any convenient position. A sliding
contact is provided at F. These wires c c are connected as in the accompanying
diagram.
Now let the sliding contact at E acting under the influence of the float make 5
connection with any point on the wire A B, Also let the contact F be shifted
along the wire C D, till there is no difference of potentials between the points E
and F (which condition may be ascertained by means of the current, detector G)
Then there will always be a certain ratio between the length of the wire A E and
that of the wire C F. Now since the length A E represents the quantity of water 1
.in the cistern it follows that C F, is also a measure of the same quantity.
This invention can be applied to various other instruments in a similar way.
H. GARDNER,
166,, Fleet Street, London,
Agent for H. B. & H. R. F. Bourne,

page_text: We HENRY BLECKLY BOURNE Electrician and HENRY RICHARD FOX BOURNE,
Gentleman both of 8 Queen Anne's Grove, Bedford Park, London, do hereby declare
the nature of our said invention for "CONSTRUCTION AND WORKING OF ELECTRICAL
APPARATUS FOR TAKING THE READINGS OF SCIENTIFIC INSTRUMENTS FROM A
DISTANCE," and in what manner the same is to be performed to be particularly.
described and ascertained in and by the following statement :—
The object of our invention is to provide a simple means of reading various
instruments such as Barometers, Thermometers, etc. at a place remote from the said
instrument.
For this purpose we arrange a battery or other generator of electricity, sundry
wires of suitable material, and a galvanometer or other instrument for detecting
electrical currents, in the manner shown in the accompanying diagram Figure 1.
When the wires A. B, C D, A C, B D are connected together as shown, together
with the battery P and the galvanometer G and G E, GF, then (by the principle
of the "Wheatstone's Bridge ") if the points E and F, are moved; so that there is
no difference of potential between the points E and F, the lengths of A E, E B,
C F, F D, will bear a certain ratio to one another whence the position of the
points E or F may be calculated and if A B represent the scale of an instrument
the position of E will represent the position of the index on the said scale.
In order to more clearly indicate the method of applying the above principle to
our invention, let us suppose we desire to indicate the quantity of water in a
cistern, at a distance from the same. In this case we provide a suitable float
which by rising and falling with variations in the level of the water, will indicate
the quantity thereof. Now in order that the position of the said float may be
ascertained at a place remote from the same, we fix in a convenient position a wire
or strip, preferably of platinum or other inoxidizable material, having a high
electrical resistance, corresponding to A B in the accompanying diagram. At the
point E we provide a sliding contact, which is connected by suitable mechanical
contrivances with the above mentioned float, in such manner that the said float, in
moving, will also move the sliding contact. The sliding contact is at E on the
diagram.
It will thus be seen that the position of E on the wire A B, will afford an
indication of the level of the water in the cistern. The wire C D and the current
detector G are located at the above mentioned remote place, the battery P being in
any convenient position. A sliding contact is provided at F. These wires are
connected as in the accompanying diagram.
Now let the sliding contact at E, acting under the influence of the float, make
connection with any point on the wire A B. Also let the contact F be shifted
along the wire C, D, till there is no difference of potentials between the points E
and F (which condition may be ascertained by means of the current detector G.).
Then there will always be a certain ratio between the length of the wire A E, and

page_text: that of the wire C F. Now since the length A E represents the quantity of water
in the cistern, it follows that C F is also a measure of the same quantity.
This invention can be applied to various other instruments in a similar way.
One method of carrying out this invention is shown in Figure 2, where T
represents the transmitting instrument, which is placed in such position that the
arma, carrying the contact roller may be rotated by the instrument the readings
of which it is desired to transmit to a distance, such mechanical devices being used
as will render the angular movement of the said arm proportional to the quantity
to be measured. Thus if we wish to use this arrangement for measuring the height
of water in a cistern or reservoir, we wrap a cord provided with a float and
counterpoise round the axle to which the arm a is attached, or round a pulley or
drum attached or connected thereto. A conductor c, c, c, is stretched round a disc
of insulating material, such conductor having a circular, rectangular or other cross
section, but preferably being in the form of a fine wire of platinum or other inoxi-
dizable material having a high electrical resistance.
The receiver R (Figure 2) is similar to the transmitter, the ends of the con-
ductors c, c, c, and c¹, c, c¹, are connected by the line wires L, L. In the form of
apparatus.shown in Figure 2 it is convenient to place resistance coils o, o¹, between
the ends of the conductor c¹ c c and the line wires L L, so that the current
detector G may be placed at one end or station of the line as shown.
2"
"
The contact rollers and r¹ are connected together, a battery or other source of
electricity being included in the circuit. If more convenient one pole of the
battery may be connected to one roller, and the other pole put to earth, the other
roller being also put to earth. It will thus be seen that if by means of the
generator P, or otherwise, a difference of potential is maintained between the
rollers and ¹, the current produced thereby will be divided into two portions, one
flowing through L and the other through L¹.
When the apparatus is arranged as above described the coils o and o¹ having
respectively the same resistance as the line wires L and L', and the conductors ccc
and c¹ c¹ c¹ being of the same length, and having the same electrical resistance per
unit of length, the action will be as follows:-For any position of the roller? on the
conductor c cc, there will be a corresponding position of the roller rl on the
conductor c c c¹, when the current detector G indicates no difference of potentials
between the points of connection of the coils o and o' and the line wires L and L';
if now the roller r is moved a certain distance along the conductor cc c, the roller i
will have to be moved the same distance towards the same point in the line wire
along. the conductor c¹ c¹ c¹, in order that the detector G may still indicate-no-
difference of potentials between its terminals. If we omit the resistance coils o
and o¹, and if the conductors c c c and c¹ c¹ c¹ are not of the same length, and have
not the same resistance per unit of length, and if each of the said conductors is of
uniform resistance throughout; then if r is moved a certain distance x along c c c,
will have to be moved through a distance z along c¹ c¹ c¹ which will bear a fixed
relation to x. If the conductors have not a uniform resistance throughout, the
relation between x and x will have to be discovered and the scales arranged
accordingly.
:
Another type of receiving instrument is shown in Figure 3, it may be used with
the transmitter shown in Figure 2. In this case the current detector G has two
coils wound in opposite directions, one included in the circuit of each of the line
wires Land L¹, said coils being so arranged that when the current flowing in the
line wire L is equal to that in the line wire L', they will neutralize each other, and
therefore produce no effect.
Two other methods of ascertaining the equality of the currents in the two line
wires Land L are shown in Figures 4 and 5. In' Figure 4 in addition to the
contact roller two rollers, 2 and 3 are attached to the arma, but 'insulated
therefrom and make contact with the conductor c¹ cc¹; said rollers being
respectively connected with the terminals of the current detector G. These rollers 72
and 2 are on opposite sides of the roller ¹, and equidistant therefrom, and hence

page_text: 17 1
the resistance of that part of the conductor & c¹between and is the same as
that between and (the resistance of the conductor being uniform); and if
equal currents are flowing in the two circuits, from 1 to (Figure 2) there will, be
no difference of potentials between the two points, where and touch c¹ c c.
This condition can be ascertained by means of the current detector, G.;
ft
In Figure 5 in place of the conductor c¹ c c in Figure 1, there are two similar
conductors c2 c2 and c³ ³, one end of c² ² is insulated, and the other is connected to
the line wire L', and one end of c³ ³ is connected to L, the other end being
insulated. Two rollers 2 and ³ make contact with these conductors as shown in
the Figure. These two rollers are connected to the terminals of the current
detector G, and are also connected together by the resistance coil o; this coil is
connected with the battery P, and the roller r of the transmitting instrument
(see Figure 2), this connection being arranged in such a manner that an equal
resistance is interposed between each of the rollers ² and ³, and the point of
connection with the battery. Then if the currents flowing in the two halves of
the resistance coil o (which are the same as the currents flowing in the two line
wires L and L¹) are equal, there will be no difference of potentials between the two
rollers and ³, and therefore no indication on the detector G.
The action of the. three forms of receiving apparatus shown in Figures 2, 3, and 4
is this: Let the resistances of the line wires Land L¹ be equal; then when the
currents in the two circuits are equal (which can be ascertained by the current
detector in each case) the resistances of the two halves will be equal. From this it
follows that if when the resistances are thus balanced, the roller r is moved' a'
certain distance in one direction along the conductor ccc (Figure 2); the rollers, in'
Figures 3, 4 and 5 will have to be moved an equal distance to reproduce this
balance.
It is not necessary that the conductor should be stretched round a disc; all that'
is required being that it shall be held or supported in such a manner that the
sliding contact or contacts may be conveniently adapted to it. Nor is it necessary
that the said contacts should be rollers as above described; any other convenient
arrangement of sliding or moveable contact may be used.
In another form of this apparatus we use mercury or other liquid for, the above
mentioned conductor or conductors (c c c or c¹ c¹ c¹), said liquid being contained in
suitable tube or tubes of insulating material, or in a groove or grooves cut in a
block of insulating material, and a conductor, (taking the place of the above
mentioned roller or rollers) being arranged to dip into and make contact with the
said liquid. Or the conductors c c may be arranged as indicated in Figure 6, where
there are a number of suitably disposed contact pieces, resistance coils being inter-
posed between them. The contact roller is arranged to glide from one of these to
the other, this varying the resistance in the two branches of the circuit. Only five
resistance coils are shown in the Figure, but is convenient to have a much greater
number.
In the types of apparatus shown in Figures 2, 4 and 5 the battery and detector
may be interchanged without affecting the action in any way.
°
In the above mentioned forms of apparatus, in order to ascertain the position of
the contact on the conductor ccc of the transmitting instrument, (and, therefore
the reading on the instrument which it is desired to transmit to the receiver R) the
sliding contact or contacts of the said receiver R must be moved by hand until no
effect is observed on the detector G.
Figure 7 shows the adaptation of our invention to a barometer. The line
wires L and L' or suitable conductors are in this case carried into the tube A of
the barometer at each end far enough to dip into the mercury or other liquid, and
preferably attached to the said tube A at B and C. A line or conductor D is
preferably used to connect the two line wires L and L' in the manner shown to cut
out the mercury and complete the circuit by earth or any convenient conductor.
Any of the receivers R hereinbefore described can be employed at the other station.
The action is as follows:- When the mercury falls at B it rises proportionately at C

page_text: and vice versa. Supposing it fall at, B.the resistance of the line L will be increased
and that of the line L' diminished, the contact r to which the index is attached at
the receiving station must now be moved until the current detector is at zero when
both instruments will be registering similarly. This arrangement is also applicable
to thermometers, &c.
In a similar arrangement sliding contacts may be used within the tube of the
barometer or other scientific instrument, insulated from and floating on the liquid
if desired and it is evident various modifications in the arrangement of the apparatus
may be made without departing from our invention.
•
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is
1. The construction and working of electrical apparatus for taking the readings
of scientific instruments from a distance substantially as described and shown.
2. The application of a circuit arranged substantially as in the Wheatstone
bridge to barometers, thermometers, and other measuring or weighing instruments,
for the purpose of reading such instruments at a place remote from the said
instruments, in the manner described.
3. The combination of a current generator, duplex circuit, differential galvano-
meter or similar current detector, movable contacts, and measuring instruments
such as barometers, thermometers &c for the purpose of reading such instruments
from a distance, the reading of the instruments at each end of the circuit being the
same, whenever the differential galvanometer is at zero, substantially as described.
and shown at Figure 3 of the annexed drawings.
4. The use of resistances in connection with circuits arranged as herein described
to allow the current detector and batteries to be placed in any desirable position
substantially in the manner shown and described.
5. The particular mode of connecting terminals of a galvanometer or other
current detector with a circuit similar to the Wheatstone bridge (for the purpose of,
telegraphing measurements &c.) by means of sliding or movable contacts arranged
substantially as described and shown at Figure 4 of the annexed drawings.