Improvements in and connected with Automatic or Thermostatic Fire Alarm Telegraph Systems.
Year: 1896

page_text: Date of Application, 7th July, 1896-Accepted, 7th July, 1897
COMPLETE SPECIFICATION.
[Communicated from abroad by JOSEPH W. FROST, of 99 Nassau Street, in the City,
County, and State of New York, United States of America, Electrical
Engineer.]
Improvements in and connected with Automatic or Thermostatic
Fire Alarm Telegraph Systems.
I, WILLIAM EDWIN HEYS of 70 Market Street Manchester in the County of
Lancaster, Patent Agent, do hereby declare the nature of this invention, and in what
manner the saine is to be performed, to be particularly described and ascertained
in and by the following statement :-
My invention relates to improvements in Automatic Fire Alarm Telegraph Systems
and especially systems in which local building circuits are connected with a main
circuit running to a central station in such a manner that the operation of the local
circuit will sound an alarm or actuate a visual signal at a central station. The
local or building circuits are provided with thermostats for operating the circuits
automatically in case of fire. In practice I employ what I call double thermostats
which do not completely change the condition of the circuit until the heat has closed
or opened the contact points at two places. When this happens a signal indicating
fire will be sent to the central station and transmitted from there automatically by
means of a repeater to the Office of the Fire Department. In the event of the
operation of the thermostat at only one point, an annunciator at the local station will
indicate that one side of the thermostat has been affected and a trouble signal will be
received at the central station, but will not be transmitted beyond that point.
will be understood that the central station will be in charge of the local company and
that it is only necessary to summon the Fire Department in the event of an actual
conflagration. Troubles, such as are caused by the operation of a thermostat on one
side only, or by a cross of the wires connected therewith will be attended to from the
central office of the company, without any demand upon the services of the fire
officials. In like manner a break in the local or main circuit and an accidental
grounding of either or a rupture or weakening of the local battery is reported
automatically at the central office but not elsewhere.
It
It will be observed that a special feature of my system is my "double thermostat,"
which may be normally closed or normally open, according to circumstances. If
closed then it is necessary that in operation it shouldopen the circuit at two points
in order to send in a fire signal; and if open the reverse action must take place to
produce the same effect. In the present instance, I employ a normally open double
thermostat as will appear from the specification which follows:
The advantages of a double thermostat are that there is little likelihood that both
the contacts of such a thermostat, will be altered at the same time, either by
jarring or from any other cause. These advantages are fortified in the present
instance by a special construction of thermostat which makes it practically impossible
to jar all the points into contact and also, to operate them all by malicious
interference.

page_text: In my preferred form of thermostat, I use a concave-convex disc as the expansible
portion or element and I place behind the disc a pair of contact pieces one of which
is located nearer to the disc than the other. It is evident that the disc in expanding
(the direction of its movement being predetermined by the shape of the disc, and by
the fact that it is held rigidly at its rim) must first come into contact with the
nearer contact piece and then with the more remote contact piece in order to
complete the fire alarm circuit. It is also evident that with such a construction and
arrangement of parts it is not likely that a jarring of the support to which the
thermostat is attached will cause the disc to touch both points at once. In fact, the
relations are such that the disc having come into contact with one of the contact
pieces, is, by reason of that circumstance, prevented mechanically from making
contact with the second contact piece, except under a gradual expansion of the disc
such as would be caused, for example by an increase in the temperature in the
neighbourhood of the thermostat. The same conditions apply to an operation of the
disc by means of a blow either of the hand or of a hard instrument. Moreover, as will
be seen, even a constant pushing on the surface of the disc directly in front of one of
the contact pieces will only result in pulling the disc farther away from the other
one. It is understood of course, that the disc is held rigidly at its rim, so that
movement takes place laterally but not in the plane of the disc to any appreciable
extent.
I combine with the thermostatic system above set forth a system of signalling by
means of an auxiliary manually operated box. The box circuit is looped into the
main circuit above referred to and is provided with devices for 'sending suitable fire
alarm signals and together with the central office apparatus is capable of receiving a
return signal sent by the operator at the central office and also of notifying the said
operator that the return signal has been received. Moreover, in case the box operator
fails to notice or is not satisfied with the return signal, he can indicate to the central
office attendant that he desires another signal, which can then be sent to him. The
same devices can be used by the box operator for making other communications to
the central office.
The receiving apparatus at the central office of the local company is the same for
both the thermostatic and the auxiliary box signals. They consist essentially of a
a closed circuit battery and a ground battery with poles normally opposed. And the
action of the signalling apparatus at the transmitting stations causes each battery to
operate, under different conditions, a separate local signalling circuit by means of
separate electro-magnets. In the normal operation of the transmitting apparatus, the
signals are received alternately on one and the other set of signalling devices. To
obviate the deterioration of the closed circuit battery, whenever the circuit is left.
open for any reason, I provide a switch for joining its poles in short circuit, and at
the same time throwing the ground battery into connection with both sides of the
open circuit.
The automatic repeater, to which reference has been made is looped into the local
circuit of the ground battery. Accordingly it is operated intermittently every time
the said local circuit is operated. I provide means, however, for rendering such
operation of the repeater ineffective for sending an alarm to the fire department,
unless the operation of the local circuit is continued over a considerable period. The
means for preventing the effective action of the repeater consists of a short circuit
cutting out the same; and the means for prolonging the operation of the local circuit
is a long tooth on the transmitting apparatus which holds the ground circuit closed
long enough for a piece of clock work to break the said short circuit, whereupon
the signals following will be duly repeated upon the instruments at the fire
Department.
The details of my system will be fully described in the specification which follows.
I may say however, that I prefer to combine with my auxiliary box (which is designed.
to be located in the building to be protected) a series of switches or circuit changers
located in different parts of the building by means of which through the medium of

page_text: an electro-magnet in the box, the latter may be started from any point. Ordinarily the
box is started by pulling a hand lever in the ordinary manner.
Another feature of my system is that I arrange for the automatic switching in of
the central office battery, that is, the main line battery, into the place of the local or
building battery when the latter grows weak or runs down altogether. This makes
it unnecessary to depend upon a single battery located at one point. By my
arrangement a substitute is provided in case the local battery fails from any cause
whatever.
If a single thermostat is used in distinction from a double thermostat, although
the danger of a terminal being jarred into contact would exist, yet, so far as all the
other advantages of my system are concerned they would apply to an organization in
which single thermostats are used as well as to one which is described as preferred.
In other words my invention is applicable broadly to a system in which any kind of
thermostat is employed although I prefer to use my own double thermostat.
My invention is illustrated in the accompanying drawings, in which
Fig. 1 is a diagram of my whole fire alarm system, with details of some of the
parts.
Fig. 2 is a diagram showing a typical circuit without regard to the apparatus.
Fig. 3 is a diagram and partly detailed view showing the position of the automatic
transmitting apparatus after one signal has been sent in.
Fig. 4 is an elevation of my annunciator.
Fig. 5 is a detail of my double thermostat.
Fig. 6 is a front elevation of the box containing my automatic signalling apparatus
and
Fig. 7, is a section of the same along the line 7-7 in Fig. 6.
Referring to the drawings by letter, A represents the signalling apparatus at a
local station, which station is a building protected by a thermostatic system of fire
alarm. B is a circuit controlling wheel forming the chief part of said signalling
apparatus, being provided with teeth, pins or projections arranged in suitable order to
represent a definite number and also with similar teeth, pins or projections for
indicating different parts or stories of the building. There is also on the periphery of the
wheel a long tooth or projection designed to change the condition of the circuit and
hold it changed for a considerable period. This wheel co-operates with spring
contact pieces a b which are located in the path of the projections and are moved
thereby as the wheel rotates under the influence of clock work. In its rotation the
projections are first brought into contact with the piece a, which is lifted off
a corresponding contact piece a¹, as the projections pass under it. The
part of the contact piece a, with which the projections make contact, is of
insulating materials, as shown, or is suitably insulated. The point of the contact
piece b is not insulated, and is part of a spring which is attached to the same support.
with the contact piece a, thus being connected to the circuit beyond the latter
contact piece. The spring 6 bas an opening which passes over the end of the
insulating point of the spring a. In practice I prefer to use a resistance coil and
let the parts a a¹ form a normal shunt around it. In this way the main circuit is
never open except by a break in the line."
At the central office Z is a constant battery C the circuit of which is closed through
a magnet D from which it passes by a wire 1 to a circuit terminal c¹. It will be seen
that the mentioned terminal forms one of a pair, the other being c and the two being
joined by an insulated metallic piece b¹ on the armature E' of the magnet E, when
the latter is energized sufficiently to hold its armature down. From the terminal c
the circuit proceeds by wire 3 to the springs a and b and contact piece a¹ thence
back by wire 4 to the opposite terminal of the battery C passing on its way through
the auxiliary box apparatus at W and the circuit breaker F located at the central
office. Such is the normal circuit of the constant battery and it is evident that this
circuit is broken and the magnet D de-energized, every time a tooth or projection on
the wheel B lifts the spring contact off its corresponding contact piece a Behind the
armature E¹ is a contact spring 122 with which the insulated contact piece b' supported

page_text: on the armature makes electrical connection when the armature is drawn back. This
same contact piece & is kept always in electrical connection with the terminal c by
an extensible spring 141.
Now the magnet D controls in the usual manner a local alarm and register or
recorder circuit, which is operated every time the armature of the magnet D falls
back. Accordingly the breaks in the circuit caused by the nction of the transmitting
apparatus at the building to be protected as above described, will produce a registry
or a record and an alarm at the central office upon the local apparatus controlled by
the magnet D.
The wheel B is connected to the armature of the magnet E which armature makes
contact, when down, with the core of the magnet. The latter is joined by a wire 5
to ground at G. On the back of the wheel B is a lug e forming the arc of a circle
and pressed upon by a spring el which is also connected to ground by wires 6 and 7.
The wires 5 and 6 are led to the springs 8 and 9 respectively, the said springs being
normally joined to each other as shown.
From the above it is evident that the wheel B is connected to ground both through
the armature of the magnet E, when that is down, and also through the lug e and the
wires 6 and 7 while the spring e' is resting upon the said lug. The lug is made long
enough so that the spring will rest upon it during the time required for sending the
box signal once. The object of this is to provide that a ground shall always be on
during the sending of the first box signal even though the local battery P' should be
weakened or ruptured after the beginning of the signal, and should thereby allow
the ground through the core of magnet E to be thrown off by the falling back of
armature E. If some provisions were not made, the full signal might not be
received on the central station apparatus now to be described.
At the central station Z, there is also a battery H, opposed in polarity to the
battery C, and with one pole connected to ground. This battery has in its circuit a
magnet I, which controls an independent local alarm and register or recorder circuit,
closing it every time the armature of the magnet I is brought forward. A push
button J, is inserted in the circuit of the battery H, between the magnet I and the
battery C. I also place in the circuit of the former battery a switch K, for opening
the circuit whenever an accidental ground occurs on the line.
Whenever, now, the box apparatus located at the building to be protected is set in
operation by the closure of a thermostat or from any other cause, the action so far as
the ground circuit apparatus is concerned, is as follows:-
In this
The
The teeth or projections on the wheel B, after operating the spring a as already
detailed and causing the actuation of the receiving apparatus controlled by the
magnet D, come into contact with the bare spring b, forming a ground through the
said spring and completing the circuit of the battery H, to the magnet I.
way the second local receiving apparatus is actuated in an obvious manner.
distances between successive teeth or projections on the wheel B, and that between
the bare contact point b, and the insulating point on the spring a, are so adjusted
that contact is made between each tooth and the mentioned points, successively
before the next tooth touches either point. Thus, each element or unit of the box
number received at the central office is alternately on one and the other local receiver.
The teeth, pins or projections on the periphery of the wheel B, may be arranged to
represent any desired number. In the present instance they are shown as
representing the numbers 35. Moreover, the pins representing the numbers are
twice repeated in the form illustrated, but they may be repeated as many times as
shall be necessary or desired. Beyond the pins representing the number are single
pins arranged to represent different stories or parts of the protected building.
Between the two number groups is shown a long projection e, the object of which
is to hold the main circuit changed for a considerable period. In effect the projection
is made to close the ground circuit long enough to cause a repeater controlled by
the said ground circuit to operate effectively. It will be observed that a loop is
formed in the local circuit controlled by the magnet I, which loop includes a relay L,
a trip magnet M, and a magnet N, whose armature forins, a support for a pinion ",

page_text: and a disc n', having an insulating portion n². The armature of the relay L, controls
a normally closed circuit running to the fire department, as shown. When the
armature of the said relay is drawn towards its magnet, it tends to break the said
circuit and sound an alarm, and actuate a register at the fire department through the
medium of a relay 0, controlling a local circuit. The said arinature of the relay L,
is, however, normally short-circuited by the wires 10, and 11, one of which runs to the
frame of the clock work o, of the repeater and the other of which is connected with
an insulated spring 12 which bears upon the periphery of the disc n. The pinion is
adapted to engage with a clock work o, when the arinature of the magnet N is drawn
up to its poles. Normally, however, it is disengaged therefrom. When engaged the
clock work causes it to rotate in the direction of the arrow and carry the disc n¹ with
it. The magnet M, is merely a trip magnet which releases the clock mechanism of
the repeater every time its arinature is attracted.
Now, whenever the local circuit including the magnets I., M, and N is closed, all
the said magnets are operated; the clock work is released, the pinion is drawn into
engagement therewith, and the local circuit running to the fire department is opened
by the relay L. The said opening of the circuit however, is not effective for operating
the relay O, because of the short circuit already referred to. Moreover, the disc n'is
only moved so long as the local circuit is closed, and unless the closure lasts some
considerable time, it is not carried far enough to bring the insulating portion n
under the spring 12, and so break the short circuit. A weight p, carries the disc ',
back to its normal position so soon as it is released. When, however the local circuit
remains closed for a considerable period, the disc is carried until it brings the
insulating portion n², under the spring 12, thus breaking the short circuit. Then
the breaks of the circuit by the action of the relay L, will operate the relay 0, and
intermediately the gong and register controlled thereby.
The ordinary operation of the ground circuit by the pins on the wheel B, are too
short to cause the repeater to send the signala on to the fire department. But the
long projection holds the circuit closed long enough to make the repeater break
the short circuit through 10, 11, 12 and the disc and frame, and allow the succeeding
signals to be transmitted through to the fire gong and register. Thus in practice,
with an apparatus constructed as shown in the drawings the first number signal will
be received only at the Central office of the Local Company.
This will indicate trouble as will appear hereafter and the trouble can be attended
to by the authorities of the company without disturbing the fire department. A
repetition of the number signal will indicate fire and this will be automatically
transmitted to the fire department as above made clear.
Of course, the long projection described may be preceded or followed, or both, by
as many number groups as may be thought desirable; in which case a single number
signal would indicate trouble of one kind, as a break, a double signal would indicate
trouble of another kind, as a ground or a cross, and so on.
Having described the action of the receiving apparatus and to some extent also the
action and construction of the transmitting apparatus at the building to be protected,
I will describe now the latter apparatus in detail and also set forth the circuits and
other devices connected with the transmitting apparatus and controlling the same.
In general I may say that I provide at the Local or building station, a series of
conductors. running through the different stories of a building and through a trip
magnet controlling the signalling mechanism, the circuit being provided with
thermostats, arranged so as to cut out the trip magnet when closed, and set the
mechanism into operation. Some of these wires I call the main building wires and
sone I call section or loop wires. The two groups of wires are in series on opposite
sides of the trip magnet so that a cross between them will cut out the said magnet
and release the mechanism. At the local station is a battery P the circuit of which
is closed over the following route; wire 13, switch 14, main wire 15, spring 16,
contact 17, spring 18, main wire 19, switch 20, wire 21, trip magnet Q, wire 22,
switch i, section loop wire 23, switch j, connection 24, switch k section loop wire 25,
switch, wire 26, resistance coil E, constituting a magnet, wire 27, spring 28,

page_text: contact 29, spring 30 and wire 31, to ground; thence by way of ground G¹ and
wire 32, spring 33, contact 34, spring 35, and wire 36, to opposite pole of the battery.
Between the loops or section wires 23 and 25 and the main building wires 15 and 19
are arranged thermostats T T as shown. It will be seen that the section wires or a
portion of them are arranged between the two main wires and that the thermostats
present two open contacts, both of which must be closed to make a cross between the
two main wires and the section wires. It is of course understood that the thermostats
are located upon the walls or ceilings, generally the latter in such positions
where they would be likely to be influenced quickly by the heat of a fire taking
place in the room where the thermostats are located. They will ordinarily be placed
in all parts of the protected building where they would be likely to be of service.
The contacts 17, 29 and 34 are metallic pieces secured upon or in an insulated
cylinder or drum U, and the springs 16, 18, 28, 30, 33, and 35 normally press upon
the said contacts. On the same drum are other contacts 37, 38, 39, 40, 41, 42, and 44,
with which other springs co-operate in groups of two or three as will be explained
hereinafter. The drum U is pivoted in an upright position and carries upon the end
of its shaft a yoke V, which, together with the drum is rigidly secured to the shaft.
Normally, that is, the position in which the springs 28 and 30 rest upon contact 29,
and the springs 33 and 35 rest upon oontact 34, the yoke is so turned as to present
its opening to a pin t, on an arm P¹ carried by the number wheel. When the latter
is released and allowed to travel in the direction of the arrow, the said pin t, engages
the yoke and turns it and the drum part of a revolution. This shifts the contacts on
the drum from under the springs referred to and brings the other set of contacts
under the springs with which they co-operate as above set forth.
Now it will be seen that the loops 23 and 25 referred to in the foregoing and
which in the present instance are two in number, are connected in series. The ends
and the middle of the loops are connected inside the box apparatus by means of
wires 45, 46 and 47 to springs 48, 49 and 50 respectively. These springs bear
normally upon the insulating surface of the drum, but are adapted to rest upon the
· contact 44 after the drum has been moved.
It will be observed that a wire 51 leads from the contact springs 122 to a spring 52
.resting on the insulating drum. When the switch has been turned this spring rests
with the springs 48, 49 and 50 upon the contact 44. Similarly a wire 54 runs from
the contact piece c', to a spring 55 which, at first, insulated, is afterwards brought to
rest upon the contact 40 together with the spring 56, which latter is connected by a
wire 57. to a spring 58 and by a wire 59, with the wire 13. The spring 58 co-operates
with the contact 37, in the second position of the switch and also with the spring 60
which rests upon the same contact at the same time and is connected by a wire 61 to
the wire 21. From the wire 15, I make half connection to the spring 62, which in
the second position of the switch becomes connected to the spring 16 through the
contact 38. In like manner a spring 63 joined by a half connection with the wire 19
is thrown into co-operation with the spring 18 through the contact 39 after the
moving of the switch. Thus it is clear that the operation of the switch U throws
together the two ends of 19 to form a loop, also the ends of 15 and also the ends of
the loop wires through the parts 48, 49, 50, and 44. The apparatus, then, is in
such a condition that a cross between the wires will take effect in either direction,
thus nullifying the effect of a broken wire or even three broken wires. By means
which will be explained hereinafter the apparatus will itself prevent a single cross
from sending other than a trouble signal but a double cross will be effective for
sending in a complete alarm. The same act, that is, the act of moving the switch
throws the springs 30 and 33 together through the contact 42 and it also throws the
spring 28 into connection with the spring 63 through the contact 41. The last
named spring is joined to spring 35 within the box.
A short circuit formed by wires 64 and 65 and springs 66 and 67 in combination
with the lug 68 on the bottom of the number wheel, serves to cut out the trip
magnet while the first signal is being sent in, so that a partial signal may not be
transmitted...

page_text: I also provide a cut out or short circuit for the main line battery through the
wires 69 and 70 and the springs 71 and 72, the arrangement being such that when the
box is closed this short circuit will be open, but will be closed when the box door is
open. I provide similar means for keeping in contact the.springs 8 and 9 in the closed
condition of the box and for breaking the contact when the door is open. This is
done in order to prevent the central office apparatus from being actuated in the
handling of the automatic transmitting apparatus as by winding up the box when
the door of the box which contains the said transmitting apparatus is open.
Now it is clear that the transmitting apparatus may be set into operation by any
one of four or five causes. For example an accidental break in the circuit, or an
accidental ground, or a partial operation of the thermostat, or what is the same
thing in effect, a cross between the main and section or loop wires of the building,
or a weakening or running down of the battery or finally a complete action of
a thermostat will cause the trip magnet to be de-energised and so release the
signalling mechanism.
Take, for example a break in one of the building wires, say, wire 15. This
wire forms a part of the normal circuit of magnet Q, and hence its rupture will
break the circuit of that magnet. The same would be true of the wire 19 of either
of the loop or section wires 23 or 25. The mechanism in any case is set free and
begins to rotate in the direction of the arrow. This continues until the pin t has
shifted the switch U as already set forth. Meanwhile, the first signal has been
sent in. After the shifting has taken place, the original circuit of the magnet Q
is broken and a new circuit for the same is formed over the following course :
Battery P, wire 36, spring 63, contact 41, spring 28, wire 27, magnet E, wire 26
and wire 45, spring 48, contact 44, spring 50, wire 47 and wire 22 magnet Q,
wires 21 and 61, spring 60, contact 37, spring 58 and wire 59. Accordingly if the
starting of the signalling mechanism has been due to a break in the circuit, the
said mechanisin will be stopped after the sending of a trouble signal to the central
office. It will be observed that the course last described does not include any of
the loop or main building circuits and accordingly it makes no difference whether
one or all of such wires are broken at the same time. It will be seen hereinafter that
the breaking of a wire or wires as above set forth will not prevent the sending in
of a true fire alarm signal in case the thermostat is closed on both sides.
It has already been shown that the battery P is grounded over the wire 36,
spring 35, contact 34, spring 33 and wire 32. It has also been made apparent
that the main building wires forin part of the circuit between the battery on the
other side and the trip inagnet Q. Therefore, if an accidental ground should take place
on this part of the circuit, the trip magnet would be cut out and the mechanisın
released. The shifting of the switch, however, throws off the original ground and
thus interrupts the short circuit, restoring the circuit through the magnet Q and
stopping the mechanism.
It is also apparent that the accidental grounding of a section or loop wire, say
either 23 or 25 will cut, out or short circuit the resistance magnet E. Consequently
the armature of that magnet will be retracted causing a short circuit around the
trip magnet Q, by way of the wire 21 wire 120, back stop 121, armature E, wire 123
and the frame of the clock, work together with wheel B, lug e, spring e', wire 6,
spring 9, and wire 7. Thus the mechanism will be set free as before and with the
same result. That is, the apparatus will run until the switch U is turned, when
the circuit alrendy traced in the paragraph describing the effect of a break will be
formed, and the short ground circuit cutting out magnet Q will be broken and the
circuit restored.
No part of the circuit can therefore be grounded accidentally without notification
at the central office, except the short ground wire between magnet E and battery P.
Of course the restoration of the circuit takes place through the trip magnet Q and
the resistance magnet E whereby the armature of the latter magnet is drawn down
and the normal ground through the core thereof is restored.
Suppose now that a thermostat T closes on one side only or that a cross take

page_text: place between one of the main and one of the loop wires, say, between 15 and 23.
This will of course cut out the trip magnet with the same effect as before.
The apparatus will now continue to rotate until the arm P¹ has been brought into a
position where it lifts the spring portion of the switch 14 off the contact with
which it co-operates. Now when this takes place the short circuit between 15 and 23
is broken and does not avail longer to cut out the trip magnet, the circuit of which
is now over the course described for the restoration of a broken circuit. The
mechanisin is accordingly brought to rest at a point where it will indiente a particular
kind of trouble, that is, the closure of one side of the thermostat. If the closure
had taken place between 19 and 25 instead of between 15 and 23, the mechanism
would have been stopped when the arm P operated the switch 20. It will be seen
that the mechanism stops at a different point for these two troubles and it will be
seen that these points are both different from those at which the mechanism stops
in case of a full action of a thermostat. This can be utilised if desired to cause a
pointer 100 on the shaft of the wheel B to turn to different indications on an
annunciator in which all troubles are indicated by a single sign while the different
stories of the building are indicated by separate signs 1, 2, 3, 4, etc.
In case both sides of the thermostat are closed at the same time, then the
operation of the switch 20 will not stop the mechanistn, as there would still exist
another short circuit around the trip magnet besides that through 19 and 25, that is
by way of 15 and 25. Similarly, the operation of the second switch, that is 14, will
fail to stop the signalling apparatus. Therefore, that apparatus will continue its
-rotation until the arm P has been brought into a position where it lifts the spring
portion of the switches i, j simultaneously off their co-operating contacts. Now if
the closure has taken place at one of the lower thermostats, located on the first floor
or story of the building, then the mechanism will be brought to rest, as the short
circuit around the trip magnet will have been broken. If, however, the thermostat
which has set the mechanism into operation is on the second floor or story, then the
mechanism will move on until the switches k, l, have been operated simultaneously.
Meanwhile, in the first instance, the building signal will have been sent in twice
repeated and one of the single pins will have operated the circuit, so as to indicate
the first story. Or, in the second instance the same thing will have taken place,
except that two pins will have operated the circuit after the number signals for
indicating the second story. It will be remembered that the second number signal
and the story signal or signals, inasmuch, as they follow the long projection e² are
repeated automatically through the central office to the fire department.
Owing to the loop arrangement of the section wires it is possible for fire alarm
signals to be sent in, even though both mains should be broken and the loop also at
a single point.
We have now to consider the effect of a weakening, rupture, or running down of
the battery P. This would both release the mechanism by de-energizing the trip
magnet, and would allow the armature of the resistance magnet E to fall back
breaking connection between the contact terminal c and c¹. At the same time the
main battery C will be switched into the place of the local battery completing a
circuit through the trip magnet, as will be apparent by examining Figs. 1 and 3
and supposing the armature of magnet E to be contracted. The circuit after the
release of the resistance magnet armature may be traced as follows: By
wires and 54 spring 55, contact 40, spring 56, wire 57, spring 58, contact 37,
spring 60, wire 61, wire 21, magnet Q, wire 22, wire 47, spring 50, contact 44,
spring 52, wire 51, contact spring 122, contact piece b, spring 141, and wire 3 and
The circuit as before is restored through the magnet Q and the
mechanism stops. The battery in this instance, is, however, the main battery C
and not the local battery P.
so on.
I have made the magnet E a resistance tnnguet, because I have found that the
presence of a considerable resistance in that part of the circuit between the battery
and the section wires and trip magnet makes the short circuit formed by a cross
between the main and section wires-as by a thermostat-more effective for

page_text: de-energising the trip magnet. It serves also when energized to keep a constant
ground on the local apparatus and so provide for signals being received at the
central office on the ground apparatus. Accordingly if a signal is received at
the central office on the metallic circuit, but not on the ground, it will indicate that
the battery has run down or that for some other reason the magnet E has become
de-energized. Since, now, the automatic repeater is connected up in circuit with
the ground apparatus at the central station it is evident that there will be no danger
of the signal for weak or ruptured battery being sent in to the Fire Department,
and there received as a fire signal. It might happen that, for mechanical or other
reasons, the box might continue to rotate till run down. In such a case, no harm
would be done, as the receipt of the second signal on the ground circuit would
necessarily indicate the closure of a thermostat on both sides. On the other hand,
if the signals are, under such circumstances, received only on the metallic circuit, it
can only indicate some kind of "trouble" and not a true fire alarm. This will be
true, even though, for any reason, the box may have stopped at a point which would
ordinarily indicate fire.
The springs 66 and 67 are so placed that they will be bridged by the segment 68
just before 'the first number signal begins to operate and will continue in that.
condition until the first signal has been completely sent in. This is to avoid the
danger of the trip magnet being cut in again while the first signal is being sent,
thus interrupting a signal.
My thermostat is illustrated in Fig. 5, 102 being a base of porcelain or other
insulating material preferably vitreous. This is provided with a circular opening or
depression across which is secured by bolts at its rim a concavo-convex circular
metallic diaphragm 103. The rini rests in a countersink in the base and is held.
rigidly by the screws. Behind the disc are contact screws 104 and 105, the former
of which is slightly farther away from the disc than the latter. The action of the
dise under the influence of heat has been given in the general description at the
beginning of the specification. The object of this is to eliminate as far as possible.
the danger of both contacts being accidentally made at the same time, and to
provide for a trouble alarm only in case of an abnormal temperature but one not
warranting the calling out of the fire department. A rise of temperature sufficient
to operate the second contact within a short time of the closure of the first, would
indicate a fire heat. With this construction it is not possible to press so hard
against the disc in front of the screw 104 for example as to bring it into contact
with 105. In fact, the pressure at the point mentioned tends to move the disc farther
away from the screw 105 instead of bringing it nearer. In the same way a blow.
cannot be made to close the two contacts, and the chances of the jarring of the
building or any similar accident causing contact at both points at once are very,
remote.
The circuit connections are made through the disc, and through the contact
screws as shewn.
It may be desirable to combine with the automatic system above described a box.
system which can be operated directly, by hand, or by means of switches or circuit
changers located in different parts of a building. These auxiliary boxes may be
coupled up as here shown with an automatic system and in conjunction with the
switches and hand circuit operating devices, in the same system thermostats may be
employed if desired.
I have shown such an auxiliary box apparatus at W in the drawing. It consists
of a number wheel operated by clock work and capable of being released by hand
or otherwise in combination with other devices which will be fully explained
hereinafter.
On the winding shaft 75, of the clock mechanism is an arm 76, which rotates once.
during four revolutions of the shaft 77 and the circuit breaking wheel 78
carried thereby. At 79 is shewn a hook which projects through the sides of the box
or frame containing the clock work into a position where it can be easily manipulated
from the outside. The hook is pivoted, together with an arm 80 forming an angle

page_text: piece therewith on the shaft or pivot 81. The arm 80 rests normally on a block 82 on
the frame of the clock work and in this position it serves to prevent the clock work
from, rotation by interfering with the escapement 83. When however, the hook is
pulled down, the arm 80 is carried to the left, freeing the escapement, and slips
behind the edge of the block 82, thus preventing its return. The arm 80 presses
slightly against the surface of the block 82 and so tends to pass behind the same when
it reaches the edge. For restoring the hook it is necessary to use the hand.
Co-operating with the cirenit breaking wheel is a set of springs and contacts
precisely similar to those which have been described in connection with the circuit
breaking wheel B in the foregoing specification. Now the circuit after passing
to the springs in question, goes to the armature 84 of an electro magnet 85 within the
box W. From the back stop 86 of this arinature the eircuit proceeds back to the
central office through a magnet 87 located under the hook 79 or mainly through a
short circuit round the same. The armature 84, in passing to its rear position (which
it normally occupies) strikes against a bell or gong 88, to give a return signal, as will
presently appear.
Before passing to the armature 84, over the course described the circuit divides
and passes through both spools or bobbins of the electro magnet 85, rejoining the
main circuit beyond the back stop by way of the wire 89. This branch is itself
divided between the two bobbins, a branch being taken off and carried to a contact
piece 90. In proximity to this contact piece is another contact piece 91 which is
connected to ground. The pieces 90 and 91 are within the ranges of motion of an
insulated metallic piece 92 on the armature 84. The relations are such that the
metallic piece 92.bridges the two contact pieces when the armature is close to the
poles of its magnet. A button 93 on the back of the armature is provided in order
that the operator may push down the armature by hand at will, for signalling purposes.
The parts which I have described above as forming parts of my box apparatus will
ordinarily be enclosed in a larger box, which first must be opened, before the
mechanism described can be sent into operation. The hook 79, will project into this
larger box, so as to be accessible to anyone who has opened the outer box. The latter
box may be provided with a key for opening it or it may have a glass front which can
be broken in order to gain access to the inner parts.
To avoid the necessity of having one of these auxiliary boxes on every floor of a
building or a multiplicity of them in any desired parts of the building, I provide at places
where such boxes would naturally be located suitable switches with circuits soon to be
described running to an electro magnet 87 located in a position under the hook where
it can operate the same when sufficient current is applied. With this arrangement
the hook would have to be of magnetic material or else be supplied with an armature
on which the magnet will act. The circuits for controlling this magnet are connected
with the main circuit. The circuit passes through the electro magnet 87 or rather,
for the most part through a looped short circuit 94 around the magnet. Now the loop
circuit contains several switches 95, as many as may be found necessary or desirable.
The operation of one of these switches consists. merely in turning the movable part
thereof to a ground contact, thereby breaking the looped short circuit, completing a
ground circuit from the battery H, through the magnet 87, and also completing a
metallic circuit for the battery C through the same magnet, or rather, forcing the
current from the latter battery to go through the said magnet instead of through the
short circuit 94. This increase of current through the magnet 87 is sufficient to
cause it to pull down the hook and release the signalling mechanism. But a break in
the line will give the magnet only the current of battery C which is not sufficient to
operate the box, but will be indicated on a galvanometer at the central station.
Returning now to the local central office a four point switch 106 is placed in the
local circuit controlled by the magnet D, one pole serving to break the said local
circuit and the other serving to 'connect. the two poles of the battery C by a short
circuit which includes the magnet D. The object of this will be explained
presently.
In the normal operation of the auxiliary box apparatus the hook 79 is pulled in the

page_text: usual manner and releases the box mechanism. The signals are sent in, in the same
manner as has already been set forth in connection with the wheel B. By
the time the signal has been repeated four times the arm 76 has arrived at a position
where it presses against the outer end of the armature 84. In going farther to a
position of rest the arm 76 moves the said armature down against the poles of
the magnet 85. This breaks the main circuit which passes by way of wire 4,
contact a', spring a, wire 108, armature 84 back stop 86, and wire 109, and throws
the current of the battery C through the coil of the magnet 85. It also closes a
ground circuit for the battery H through one coil of the same magnet. The signal
having been properly received at the central office the key F is operated thus breaking
both circuits and allowing the arinature 84 to fly back which gives a return signal on
the gong 88, in doing so, and cuts itself out again. This is the normal operation of the
apparatus. In case of an accidental ground the local circuit controlled by the magnet I
will give the alarm and steps can be taken to remove the disturbing cause. Before
searching for the source of the trouble the switch K will be turned so as to open the
circuit of the battery H.
A break in the circuit will be made known by the alarm apparatus in the local
circuit controlled by the magnet D. When a break does occur the switch 106 will be
turned so as to short circuit the battery C and prevent deterioration, and at the same
time will provide a new path for the current from the battery H by way of the wire 111,
magnet. I, wire 112, switch 106 and wire 113. Thus even when the line is
broken the magnet I and the local apparatus controlled thereby will serve as
receiving instruments for all signals from the box apparatus in either direction.
It is evident that the local alarm and registering or recording apparatus connected
with the magnet I, will continue to operate as long as the armature of the magnet 85
is attracted or held to its pole, thus indicating to the attendant at the central office
that the said magnet has been properly cut in and that the box operator is ready to
receive the answer back signal. This the attendant gives ordinarily by pressing down
the key F, .de-energizing the magnet 85 and letting its armature fly back,
in doing which it gives the signal on the gong 88. Should the operator
at the box fail to notice the return signal or be in doubt about it, he can push the
armature down by means of the button 93, starting the sending apparatus at central
office and wait for an answer. By following a code agreed upon the box operator can
communicate any desired want or information to the operator at the central office.
This feature of the system would be valuable in police telegraphs.
If the answer back signal fails totally of operating the central office attendant will
be made aware of the fact by the continued operation of the alarm and other
apparatus connected with the magnet I. This will shew a derangement of the box
apparatus even if the person who has pulled the box has not waited to communicate
after the signal has been sent in.
By making my ground connection from a point between the bobbins of the
magnet 85 (or between two separate magnets as the case may be) I insure the
possibility of giving an answer back signal, even if the line should be broken. When
the armature 84 is once down, the current through a single bobbin will be enough to
hold it. Accordingly the switch 106 having been operated as already detailed and a
signal sent and received on the receiving apparatus at the right in Fig. 1 the
armature 84 will be held down and the attendant can answer back by operating the
key J and releasing the armature.
The signalling apparatus both in the automatic and manial parts of the system is
restored to its original position by hand. In restoring the wheel B the switch
devices are returned to place through the medium of the yoke V and the pin T.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed, I declare that what I claim is :-
1. In an electrical alarm system, the combination with a signalling mechanism,
and an electro magnet. normally controlling the same, of a closed circuit through the
said magnet, the said closed circuit being looped between the magnet and the battery

page_text: on each side, cross connections, normally open, connecting opposite sides of each loop,
and mechanically operated switches adapted to close said cross connections, as set forth.
2. In an electrical alarm system, a closed electric circuit including a translating
device such as an electro magnet and including a series of loops, located between the
said magnet and the battery which supplies the circuit, normally closed connections
between successive loops, cross connections, normally open, connecting opposite sides
of each loop, and devices for opening said closed connections and closing said open
connections, as set forth.
3. In an electrical alarm system, a closed electric circuit including a translating
device such as an electro magnet and including a series of loops, located between the
said magnet and the battery which supplies the circuit, normally closed connections,
between successive loops, cross connections, normally open, connecting opposite sides
of each loop, and automatic devices for opening said closed connections and closing said
open connections, as set forth.
4. The combination with an electro magnet of a closed circuit through the said
magnet, the said closed circuit including one or more loops located between the said
magnet and the battery which supplies the circuit, cross connections normally open
connecting opposite sides of such loop, and mechanically operated switches for
closing the said cross connections simultaneously or substantially so, as set forth.
5. In an electrical alarm system, the combination of a signalling mechanism and
an electro magnet normally controlling the same, of a closed circuit, the said closed
circuit including a series of loops with cross connections between successive loops,
normally closed, and cross connections normally open, connecting opposite sides of
each loop, and devices operated simultaneously with said signalling mechanism, when
actuated, for opening the said closed connections and closing the said open connections,
as set forth.
6. In an electrical alarm system, a signalling mechanism provided with distinctive
signalling devices, an electro magnetic controlling device therefor, circuit controllers
governing the said electro magnetic controlling device, the said circuit controllers
being each provided with three or more contact parts in groups of two, all in
combination with circuits and connections, substantially such as described, whereby
on the operation of either or both groups of contact parts, definite signals will be
transmitted, as set forth.
7. In an electrical alarm system, a signalling mechanism provided with distinctive
signalling devices, an electro magnetic controlling device therefor, thermostats
governing the said electro magnetic controlling device, each thermostat being
provided with three or more contact parts in groups of two, all in combination with
circuit and connections, substantially such as described, whereby on the operation
of either or both groups of contact parts, definite signals will be transmitted as set
forth.
8. In an electrical alarm system the combination with a signalling mechanism and
an electro magnet normally.controlling the same, of a closed local or building circuit
through the said magnet, and a switch operated by the said signalling mechanism,
when actuated, the switch terminals being connected with the local circuit, one on
each side of the magnet, whereby a break in the said circuit will be short circuited
and the circuit restored through the magnet as and for the purpose set forth.
9. In an electrical alarm system, the combination with a signalling mechanism,
an electro magnet, normally controlling the same, of a closed circuit through the said
magnet, and a switch operated by the said signalling mechanism, when actuated, the
switch terminals being connected with the closed circuit, one on each side of the
magnet, as and for the purposes set forth.
10. In an electrical alarm system, the combination with a circuit controlling
mechanism, provided with distinctive signalling devices, and an electro magnet
normally controlling the same, of a closed circuit through the said magnet, and a
switch operated by the said signalling mechanism, before the sending of the second
signal, the switch terminals being connected with a closed circuit one on each side of
the magnet, whereby on a break in the local circuit a signal will be sent, and the said

page_text: break will be short circuited, and the circuit restored through the magnet, as and for
the purposes set forth.
11. In an electrical alarm system, the combination with a circuit controlling
mechanism provided with distinctive signalling devices, and an electro magnet
normally controlling the same, of a closed local or building circuit through the said magnet,
and a switch operated by the said signalling mechanism, before the sending of the
second signal, the switch terminals being connected with the local circuit, one on
each side of the magnet, as and for the purposes set forth.
12. In an electrical alarm system, a signalling mechanism provided with distinctive
signalling devices, and an electro magnet normally controlling the same, of a closed
circuit through the said magnet, and a switch operated by the said signalling
mechanism before the sending of the second signal, the switch terminals being
connected with a closed circuit, one on each side of the magnet, all in combination
with a dial in front of the signalling mechanism and a pointer connected with the
said mechanism, traversing the face of the dial.
13. In an electrical alarm system, a main circuit and a signalling mechanism
located therein and provided with distinctive signalling devices, an electro magnet
for controlling the said signalling mechanism, and a closed local or building circuit
through the said magnet, in combination with an artificial ground on one side of the
local battery aad a switch in said ground and a mechanical device operated by the
signalling mechanism, when actuated, for breaking the local ground, the said switch
being located in the line of motion of the said mechanical device, and the relations
being such that the mechanical device operates the switch, only after a pre-determined
number of signals has been sent by the signalling mechanism, whereby if a foreign
ground has short circuited the controlling magnet, the ground circuit will be
automatically broken and the circuit restored through the said magnet, but only
after a distinctive signal has been sent in, substantially as set forth..
14. In an electrical alarm system, a signalling mechanism in the main circuit, an
electro magnet for controlling the same, and a closed local or building circuit through
the said magnet, the said local circuit being branched beyond the said magnet and
extending through the building to be protected, the section and branches being on
opposite sides of the magnet, all in combination with open double circuit controllers,
such as thermostats extending between the branch and section wires, a device
operated by the signalling mechanism, when actuated, for simultaneously lifting the
ends of one of the branched wires, and afterwards those of the other, as and for the
purposes set forth.
15. In an electrical alarm system, a signalling mechanism an electro magnet for
controlling the same and a closed building circuit through the said
magnet, the said building circuit being branched beyond the said magnet and
extending throughout the building to be protected, located in proximity to section
wires, as described, the section wires and branches being on opposite sides of the
magnet, all in combination with open double circuit controllers such as thermostats,
extending between the branch and section wires, a device operated by the signalling
mechanism, when actuated for simultaneously lifting the ends of one of the branch
wires, and then those of the other, as and for the purposes set forth.
16. In an electrical alarm system a signalling inechanism in the main circuit, an
electro magnet normally controlling the same and the closed local or building
circuit through the said magnet, in combination with open circuit controllers,
such as thermostats located in multiple arc in short circuit around the magnet, and a
mechanical device operated by the said signalling mechanisin, when actuated, for
disconnecting the wires from the short circuit, the terminals of the short circuit being
located in the path of movement of the said mechanical device.
17. In an electrical alarm system, a signalling mechanism provided with distinctive
signalling devices, an electro inagnet normally controlling the same, and a closed
circuit through the said magnet, in combination with open circuit controllers, such
as thermostats located in multiple arc in short circuit around. the magnet, a
mechanical device operated by said signalling mechanism, when actuated for

page_text: disconnecting the wires from the short circuit, the terminals of the short circuit
being located in the path of movement of the said mechanical device, and the
relations being such that the said mechanical device and the said terminals for
disconnecting the short circuit works only after a predetermined number of signals
has been sent.
18. In an electrical alarm system a signalling mechanism in the main circuit, an
electro magnet normally controlling the same and a closed local or building circuit
through the said magnet in combination with open circuit controllers, such as
thermostats, located in inultiple are in short circuit around the magnet, a mechanical
device operated by the said signalling mechanism, when actnated for disconnecting
the wires from the short circuit, the terminals of the short circuit being located in
the path of movement of the said mechanical device, all in combination with a
dial in front of the signalling mechanism, and a pointer connected with the said
mechanism and traversing the face of the dial.
19. In an electrical alarm system, a signalling mechanism, an electro magnet
normally controlling the same and a closed circuit through the said magnet, in
combination with open circuit controllers, such as thermostats, located in multiple
are in the short circuit around the magnet, a mechanical device operated by the said
signalling mechanism, when actuated, for disconnecting the wires from the short
circuit, the terminals of the short circuit being located in the path of movement of
the said mechanical device, all in combination with a dial in front of the signalling
mechanism and a pointer connected with the said mechanism and traversing the face
of the dial.
20. In an electrical alarm system a signalling mechanism. in the main circuit, an
electro magnet normally controlling the same and a closed local or building circuit
through the said magnet, open connections from opposite sides of the magnet to
opposite battery poles in combination with a mechanical device operated by the said.
signalling mechanism when actuated, for closing the said open connections, the
terminals of the said open connections being located in the path of movement of the
said mechanical device, as and for the purposes set forth.
21. In an electrical alarm system, a signalling mechanism, an electro magnet
normally. controlling the same, a closed circuit through the said magnet, the open
connections from opposite sides of the magnet to opposite battery poles, in
combination with a mechanical device operated by the said signalling mechanism,
when actunted, for closing the said open connections, the terminals of the said
connections being-located in the path of the said mechanical device, as and for the
purposes set forth.
22. In an alarm system, one or more expansible elements and two points of contact
co-operating therewith and arranged at different distances from the said expansible
element or elements, in combination with a subordinate alarm circuit, connecting
the nearer, co-operating parts, a subordinate alarm circuit connecting the, more
distant co-operating parts, and a main alarm circuit connecting all the co-operating
parts, whereby distinctive signals will be sent on the closing of either contact and of
all the contacts as and for the purposes set forth.
23. In a thermostat the combination with a concave-convex disc, held at its edges
of two or more contact pieces, co-operating therewith, and differentially located with
respect to the disc as and for the purposes set forth.
24. In a thermostat the combination with a solid expansible element of two contact
points in the path of expansion of the said element, one of the said contact points
being nearer to the said expansible element than the other, and the relations of the
parts being such that the contact of the expansible element with the more remote
contact point is mechanically resisted by its contact with the nearer point, as and for
the purpose set forth.
25. In a thermostat, the combination with a concave-convex disc, held at its edges
of two or, more contact pieces co-operating therewith, the said disc and the said
contact pieces having an adjustable relation to each other, as and for the purpose
set forth;

page_text: 26. A signalling system, provided with transmission apparatus adapted to send a
definite signal, a relay responding to the signals thus sent, a local circuit controlled
by the said relay and including a second relay which controls through the medium of
its armature, an aların circuit, a normally closed short circuit around the said
armature and means for breaking the said short circuit as set forth.
27. In an automatic repeater, a local circuit controlling a trip magnet, and a
normally short circuited arinature which controls a subordinate alarm circuit, circuit
changing devices, a clock work tending to break the short circuit around the said
relay when brought into engagement with the said circuit, changing devices, and a
magnet in the said local circuit adapted to effect the said engagement, as and for the
purposes set forth.
28. In an automatic repeater, a relay adapted to control a subordinate alarm circuit
through the medium of its armature, a short circuit around, said armature, circuit
breaking devices controlling the said short circuit, a clock work adapted to be brought
into engagement with the said circuit breaking the device for operating the same, a
trip magnet for the said clock work, and a magnet adapted to effect the said
engagement, the relations being such that when the engagement is long continued the
said short circuit will be broken as set forth.
29. In an automatic repeater a circuit breaking device mounted upon the
armature of an electro magnet, the said circuit breaking device consisting of a disc
having an insulated portion and a contact spring bearing upon the dise, a clock work.
adapted to engage with the said circuit breaking device, and a spring for restoring
the disc, as and for the purpose set forth.
30. In an automatic repeater, a circuit breaking device.consisting of a disc having
an insulated or cut away portion and a contact spring co-operating therewith, a clock
work for operating the said circuit breaking device when in engagement there with, a
spring for restoring the said dise when released from engagement with clock work
and a catch or detent for holding the disc when it is carried beyond a certain point
as and for the purposes set forth.
31. In a signalling system a receiving apparatus at a station, such as the Fire
Department Office, a local circuit for operating the said receiving apparatus the said
local circuit being controlled by the arinature of a relay, a normal short circuit around
the said arinature, a means controlled by signalling apparatus at a distant station, for
breaking the said short circuit as set forth."
32. In an electrical alarm system, signalling mechanism provided with distinctive
signalling devices, an electro magnetic controlling device therefor, thermostats
governing the said electro magnetic controlling device, each thermostat being
provided with three or more contact parts in groups of two each group being adjusted
to operate at different degrees of temperature, all in combination with circuits and
connections substantially such as described whereby distinctive signals will be
transmitted upon the successive operation of the several groups of contact parts,
as set forth.
33. The combination with a suitable transmitter, such as a push button, of a
receiving magnet, a ground circuit passing through the same, the ground at the
receiving station being taken off froin between the spools of the magnet, whereby
the receiver can be operated in spite of a break in the line as and for the purpose
set forth.
34. In a signalling system, a closed metallic circuit and a ground circuit, a circuit
controller in each, an automatic transmitter adapted to operate both circuit controllers,
a receiving magnet at the transmitter station, a short circuit around the same, an
open ground circuit led off from between the spools all in combination with a push
button or its equivalent at a distant station, and with devices actuated by the
transmitter in its operation for breaking the said short circuit, and closing the said
ground circuit, as and for the purpose set forth.
35. In an electric alarm system, a signalling mechanism an electro magnetic
controlling device therefor included in a closed circuit, the said closed circuit
including one or more loops on either side of the said electro magnetic controlling

page_text: device, open circuit controllers in multiple are relation between opposite loops and an
artificial resistance interposed between the battery and the loop or loops on either side
as set forth.
36. In a signalling system the metallic circuit and a battery therein,
a branch or derived earth circuit and a battery therein, with opposed poles, a
circuit controller in each and mechanism adapted to operate the said circuit
controllers successively, the said mechanism being grounded in a combination with
two sets of receiving apparatus one in the metallic and one in the derived earth
circuit, as and for the purpose set. forth.
37. In a signalling system, a metallic circuit and a battery therein, a branch or
derived earth circuit, and a battery therein, a circuit controller in each and mechanism
adapted to operate the said circuit controllers successively the said mechanism being
grounded in combination with two sets of receiving apparatus and each set including
recording mechanisın, one in the metallic, and one in the derived earth circuit, as
and for the purpose set forth.
38. In a signalling system a metallic circuit and a battery therein, a branch or
derived earth circuit, and a battery therein, with opposed poles, a circuit controller in
each and mechanism adapted to operate the said circuit controllers successively, the
said mechanism being grounded in combination with two sets of receiving apparatus,
each including recording mechanism, one in the metallic and one in the derived
earth circuit, as and for the purpose set forth.
1000