Apparatus for Obtaining Readings from Indicators Placed at a Distance by the Agency of Electric Currents.
Year: 1889

page_text: Date of Application, 28th Mar., 1889-Accepted, 8th Feb., 1890
COMPLETE SPECIFICATION.
Apparatus for Obtaining Readings from Indicators Placed at a
Distance by the Agency of Electric Currents.
I, THOMAS JOHN MURDAY of Felton in the County of Northumberland, Gentleman,
do hereby declare the nature of this invention and in what manner the same is
to be performed, to be particularly described and ascertained in and by the following
statement:
This invention relates to apparatus for obtaining from any distance-say up to three
or four thousand miles-the readings of indicators of scientific instruments or
mechanical appliances generally, such as in meteorology, aneroid or mercurial baro-
meters, metallic thermometers, anemometers, wind vanes, rain gauges; also of gas and
water meters and steam and other pressure gauges in ordinary use. It may be applied
for transmitting readings of indicators from or above the ground level, from the depths
of mines, and from the sea or other waters.
It consists essentially of two parts in electric communication with each other, one
part situated at the "home" station or office and the other part placed in proximity
with the indicator at the "distant" station from which it is required to obtain the
readings. A cable of two conducting wires forms the connection and is the means of
communication between the two parts of the apparatus.
In the accompanying drawing the invention is shewn by way of example, applied
to transmit the readings of an aneroid barometer, Fig. 1 being a front view of the
"distant part" of the apparatus, Fig. 2 a back view of the "home part," the indicating
dial being on the opposite side, and Fig. 3 a diagramatic plan of the complete apparatus
shewing the paths and direction of the two electric currents in and between the two
parts of the apparatus.
In the distant part (Fig. 1) A is the aneroid barometer; B pointer of same ;
C movable hand fixed to large wheel D; E lever for throwing round wheel F
operated by electro magnet G; H another electro magnet; I connecting rod with two
armatures attached working between electro magnets G, H, so as to throw pawl P
out of gear or in gear with wheel F; K counterpoise of connecting rod I and
armatures.
In the home part (Fig. 2) A¹ is the woodwork to the opposite side of which the
indicating dial is fixed; B' escape wheel; C contact maker fixed on rod of pendulum D¹.
making contact, when the pendulum swings, with contact spring E'; F1 electro
magnet acting on the stop arrangement; & armature fixed to stop work rod H₁
attracted by electro magnet F when current passes; I sliding bar moved along by
rod H' pushing contact spring E' out of reach of contact maker C₁; K' pawl taking
into slot in sliding bar I so as to hold this latter after being thrown into position by
current acting on armature G'; L' catch on rod H¹ for the purpose of arresting the
motion of escape wheel B'; M' counterpoise of stop work rod H¹; N square for key
to wind up spring of clockwork.
1
are two binding screws
In the general arrangement shewn in Fig. 3, + and
leading respectively from the positive and negative poles of the battery-at the home
part which is placed in a case directly under the clockwork and consists, for distances
What may be termed
of under ten miles, of from two to six ordinary Leclanché cells.
the driving or working current passes from the binding screw to the clockwork by
way of the rod of pendulum D and contact maker through wire A' to electro
magnets bat the distant part, then returns by earth to negative pole. The second
current flows through B' at the instant when the two pointers B, C, of the distant part
complete the circuit by contact, passing from the positive pole through electro
magnet stopping clockwork, then through B to distant part acting on electro
magnet n which throws the wheelwork out of gear, allowing it to run back with

page_text: the movable pointer C to zero; and after passing through pointers and wheelwork
returns by earth to negative pole. The return currents of both circuits may be taken
by a single wire in short distances, thus avoiding earth returns, but this method would
of course require a cable of three wires.
The apparatus works in the foilowing manner: The pointer of the home dial having
been set to zero of the dial scale, the pendulum D' is put in motion. This transmits
currents through the connecting cable to the electro magnet of the distant part which
acts upon the train of wheels through an arrangement of levers causing the wheels to
revolve and the movable or " false hand C to rise from the zero of the aneroid A
synchronously with the pointer of the home dial. This motion continues until the
movable or false hand C comes in contact with the real hand or pointer B, when,
through the closing of another circuit a current passes through the electro magnet
at the home part where it instantly stops the clockwork; then on by way of the cable
to the electro magnet at the distant part causing the pawl P to be thrown clear of
ratchet wheel F and thus allowing the wheels to revolve backwards bringing the
movable or false hand back to zero in readiness for starting again when a fresh
reading is required. The pointer or index at the home part now points to the
exact division on the dial at which the real hand or pointer B of the distant part
stands and is brought back to zero by hand in readiness for taking the next
reading The mechanism at the distant part remains out of gear until the first current
is transmitted again from the home part by setting the home part clockwork in
action by hand similar to setting an ordinary clock going-when the pawl P at once
comes into action and holds the ratchet wheel F until the contact of the two hands
or pointers B C brings the current once more through the electro magnet, when
pawl P is again withdrawn from ratchet wheel F by the action of the electro-magnet
and the wheels allowed to revolve backwards as before. The moveable or false hand C
carried on the axis of, or fixed to wheel D is provided with a platinum point bent at
right angles so as to come in contact with another platinum point on the real hand or
pointer B. The backward motion of the wheel work is brought about by a spring,
which is being coiled up when the apparatus is in action under the influence of the
electric currents.
The dial of the aneroid is divided from 27 to 31 inches and the false hand Con
large wheel D, moves 005 in. at each current transmitted through the driving electro
magnet, this hand moving round the dial in a series of jumps until it comes against
the real hand or pointer of the aneroid. The reading of the distant barometer is thus
obtained within an error of 005 in. which would be sufficiently accurate for all purposes.
The dial at the home part is the exact counterpart of that of the aneroid in connection
with the distant clockwork.
I have in practice found a small apparatus, such as shown in the drawing, work
successfully through a circuit of four hundred miles.
By a modification of the apparatus herein before described, the readings of a distant
indicator may be automatically received and recorded at given intervals of time on a
diagram mounted on a revolving drum, rotated by clockwork at the home station.
Such a modification is shewn in Figs. 4 and 5, in which at the distant station, a is
an electro magnet acting. on armature fixed at c by spring and brass bracket.
The end of armature carries a rod d, fitted with pawl e engaging teeth of rack f
The latter terminates in a rod g dipping down into the open leg of the syphon tube h
of the barometer or other instrument so as to make contact with the surface of
the quicksilver or other fluid therein. i is another electro magnet which acts
upon armature k, this in turn being connected with lever pivotted at m so as
to raise rod n when the armature is attracted by magnet, the rod n then striking
against tail of pawl o disengaging it from rack and also lifting rod d so as to
bring pawl e also out of gear with rack f. This latter is in connection through a
cord passing over a pulley with weight p sufficiently heavy to bring rack back
to its starting point when pawls e and o are thrown clear of teeth of rack f.x is
a portion of the case in which the apparatus is fixed, the door being removed.
At the home station an eight day clock movement fitted with electric contacts on

page_text: pendulum and pinion wheel of minute hand gives motion to a recording drum a¹
beneath it, through vertical spindle b. An electrical mechanism very similar to that
just described for the distant station then comes into operation, the only material
difference being, that instead of rack f dipping by its rod extension y into a tube h
as in distant station it carries a pencil holder c pivotted at c¹ and bent at right angles:
a lever is fitted on to lever which causes rod e¹ to strike pencil holder c when
lever is drawn down by armature of magnet i, the blow thus given causing the
pencil to mark the diagram carried on the revolving drum a¹.
In order that it may be understood how at the expiration of each hour the driving
or primary current is sent through the windings of the electro-magnets a in both
the home and distant stations, and the hereinbefore referred to marking is effected, I
will now describe the electrical connections of the two stations and trace the course
of the current in the circuits of the apparatus. I will also describe how the racks f,
return to zero or their starting points to be ready for recording the reading of the
distant indicator at the expiration of the hour.
Fig. 6 is a diagram which illustrates the manner in which at the expiration of each
hour the driving or primary current is sent through the windings of the electro-
magnets a in both the home and distant stations, and how the passage of the current
through the windings of the electro-magnet i in the home station and the consequent
attraction of the armature thereof causes the passage of the primary current to
cease.
Figs. 7 and 8 are views, on an enlarged scale, of parts of the apparatus hereinafter
referred to.
In Fig. 6, a contact spring q is fitted at each side of the pendulum fork of the
clock in the home station, so that at every swing of the pendulum contact is made
and broken, and thus an electric current of short duration is sent through the windings
of the electro-magnets a in both the home and the distant stations. Current is only
to be transmitted in this fashion once each hour, and to meet this requirement a
pin is fitted on one side of minute wheel t. A lever u which is insulated from
the metal of the clockwork by ebonite or other insulating material at y and con-
nected to one pole of the battery, is placed in such a position that the pins on the
minute wheel comes in contact with it when the minute hand reaches the hour.
The other pole of the battery is connected to the metal of the clockwork. A wire w
is attached to the contact springs to complete the circuit through the windings of
the electro-magnets a. No current can flow in this circuit until the pin s on the
minute wheel t comes against the lever u. The circuit is then completed through the
metal of the clockwork, lever u and contact springs q.
I prefer to employ a three-part cable A, Fig. 4, one wire 1 of which is used to
conduct the primary current through the windings of the electro-magnets a in both
the home and distant stations; another 2 to conduct the secondary current through
the rod extension g, to the windings of the electro-magnet i, when contact is made
in the distant station; the third wire 3 is used as a return for both the primary and
the secondary currents. Thus three wires are used in working similar to the three-
wire system used in electric bell fitting.
When the clock of the home station coming to the hour completes the electric
circuit as already described, and currents are transmitted at every swing of the
pendulum through the windings of the electro-magnets a of both the home and
distant stations, the current to the distant station comes by the wire 1 of the cable
to the binding-screw Baud thence by the wire 6 through the windings of the electro-
magnet a and on by the wire 7 to the binding-screw D) and returns by the wire 3
of the cable to the home station. The passage of this current causes the racks
at both the stations to be impelled downwards by the armatures b until the point
of the rod extension g, in the distant station comes in contact with the surface of
the liquid in the tube h. The current in the secondary circuit-which circuit is
not broken at the home station, remaining there always complete-flows through the
windings of the electro-magnet i of the home station and is brought by the wire 4 to a

page_text: zinc electrode in contact with the liquid in the tube h, and on the rod extension g,
completing the circuit as aforesaid, the current passes through the windings of the
electro-magnet i and by the wire 5 to the binding-screw D, and returns to the home
station by the same wire 3 of the cable that returns the primary current after it has
passed through the windings of the electro-magnets, a.. The current then passing
through the windings of the electro-maguet. in the home station causes the pencil
to strike the diagram and breaks the primary circuit through the clock and the
electro-magnets a, as hereinafter described, while, as already explained, the pawls
and detents e and o are thrown clear of the teeth of the racks and the latter are
allowed to return to zero under the influence of the weights p, as hereinafter
described, so as to be ready to start again when the circuit is once more closed by
the clock at the expiration of the hour.
The racks of both stations have exactly the same number of teeth to the inch so
that the pencil moves the same distance over the drum as the contact rod on the
rack of the distant station, thus recording the height of the quicksilver or other
liquid of the barometer, or other instrument.
The manner in which the passage of the current through the windings of the
electro-magnets i causes the immediate cessation of the primary current and the racks
are allowed to return to zero is as follows. A chain is attached to the end of the
armature in the home station only, and is fastened to the lever u. When the
armature is pulled downwards the chain a throws the lever u out of contact with
the pins of the minute wheel, 'thus breaking the primary circuit. A hook 111 made
of non-conducting material, on the lever u engages with a hook on a two-arm lever y,
which is formed of non-conducting material and is pivotted to the brass plate of
the clock. This engagement keeps the lever u from falling back on the pin s.
the pin s travels round the lever y is pushed aside by it and releases the hook u, of the
lever :
and the latter falls upon stop z insulated from the metal of the clockwork.
The lever u is then ready for another contact with the pin s, when the latter has
again travelled round to the position of contact.
As
In both home and distant stations the following arrangement obtains. The lever 7
is fitted at its pivot m with a light spring m₁, which enables it to remain in any
position into which it may be moved. The lever is connected to and moved by the
armature by means of the link k₁ formed with a projection k₂, shown in Fig. 7.
Owing to this arrangement, when tho armature k is pulled downwards the lever is
moved and the pawls and detents e and o thereby released from engagement with the
rack teeth, as already described, and in addition to this the armature k is enabled to
rise from the electro-magnet i the instant the circuit is broken and the current
ceases. The friction of the spring m, upon the lever I causes it to remain in the
position into which the downward movement of the armature i has thrown it, and
consequently the pawl and detent e and o are kept out of engagement with the rack
teeth and the rack returns to zero or its starting point. The lever remains holding
the pawl and detent e and o out of engagement with the rack teeth until the next
hour when the primary current is again caused to flow and the armatures 6 are
attracted, the first downward movements of which forces the rod n down, thus
allowing the pawls and detents e and o to engage with the rack teeth, and bringing
the projections kg of the links k₁ into contact with the armatures k.
In the application of this invention to the reading of syphon barometers, gas or
water gauges (such as are in use in mines and like places) modifications of the
apparatus will be used to suit the requirements of each particular gauge, barometer
or meter. In place of a train of wheels and a moveable hand making contact (as in
the case of aneroid barometers, steam and pressure gauges) a rod worked by levers,
actuated by electro magnets will be applied, the rod descending into the open leg of
syphon tube and completing the electric circuit through the fluid (mercury, water, or
oil) contained therein as just described.
The principle of the Invention can also be applied to record the depth of water.in
wells or distant reservoirs or the indications of tide gauges, also in the reading and

page_text: The
recording of electrical instruments (such as ampere meters and volt meters) at distant
stations where current for electric light is distributed over large areas.
Invention may be worked by either one, two, three or more wires.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed I declare that what 1
claim is :-
recording of electrical instruments (such as ampere meters and volt meters) at distant
stations where current for electric light is distributed over large areas. The
Invention may be worked by either one, two, three or more wires.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed I declare that what 1
claim is :-
-
The general construction and arrangement of the apparatus for the purpose
specified substantially as described and shown.
Dated this 11th day of March 1889
JAMES STEVENSON,
Gray's Inn Chambers, 20, High Holborn, London, W.C., Agent for Applicant.