IMPROVEMENTS IN AND RELATING TO ELECTRIC BURGLAR ALARMS
Year: 1884

page_text: I HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co Patent Agents
Southampton Buildings in the County of Middlesex do hereby declare the nature
of my invention. for "IMPROVEMENTS IN AND RELATING TO ELECTRIC BURGLAR
ALARMS" to be as follows:-
This invention relates to clectric burglar-alarms of the kind wherein electric
circuits extend between a number of buildings which I shall herein refer to as
"guarded structures," and an office where watchmen are kept; means being
employed to indicate at the office any attempt which may be made to gain access
to the guarded structures.
An important object of the improvement is to more effectually preclude the
tampering with the electric circuits aforesaid in such manner as to interfere with
the transmission of an alarm to the office on any attempt to gain access to a
guarded structure being made.
In order to facilitate a clear understanding of my improvements I shall designate
the circuits within the office as internal circuits and the circuits extending to, and
through, the guarded structures as external circuits.
My invention involves the combination in an electric burglar alarm comprising
an internal circuit and an external circuit, of a galvanometer or differential relay
magnet located in the office, having one coil included in the internal circuit, the
other coil included in the external circuit, and. each being adapted to affect the
galvanometer or differential relay magnet differently, and such resistances in
the internal circuit and the external circuit that the action of an electric current
passing through the two circuits will hold the galvanometer or differential relay
magnet normally in equilibrium. Any variation of resistance in the external
circuit occasioned by the opening of the door or window will effect the operation
of means whereby an alarm will be given at the office.
The invention also consists partly in the combination, in an electric burglar
alarm comprising an internal circuit and an external circuit, of mechanism at a
guarded structure whereby a number of different resistances may be successively
thrown into the external circuit by means of increasing at the office the electric

page_text: current passing through the circuits, mechanism at the office whereby, on the
increasing of the electric current, a number of corresponding resistances will be
thrown into the internal circuit and means located at the office and serving to
give an aların there in case the external circuit is tampered with in an attempt
to gain access to the guarded structure. By this feature of my invention the
resistances of the several external circuits extending to, and through, guarded
· structures may, by a watchman at the office, be from time to time changed without
occasioning the sounding of an alarm at the office. Obviously the burglar alarm
will thus be rendered incalculably more safe because, even if burglars .should,
by the treachery of a clerk or servant employed at a guarded structure or other-
wise, ascertain the amount of resistance in the structure at the time the same is
closed they cannot rely on the amount of resistance being the same when the
attempt to gain access to the structure is made, and furthermore because, even if
the resistance which is in the external circuit at the time of the commencement of
an effort to gain access to the structure is known, the change of resistance attempted
to be made a few minutes later by a watchman at the office will indicate the
burglars' presence and render their knowledge useless.
The invention also consists partly in the combination in an electric burglar alarm
comprising an internal circuit and an external circuit, of mechanism at a guarded
structure, and mechanism at the office whereby corresponding resistances may
be successively thrown into the external and internal circuits by means of an
increase of the electric current passing through the circuits, effected at the office,
and a galvanometer or differential relay magnet located at the office and serving to
give an alarm there in case the equilibrium of the resistances in the external and
internal circuits is disturbed by an attempt to gain access to the guarded structure,
and a compound key located at the office whereby the galvanometer or differential
relay magnet employed for causing the sounding of an alarm may be cut out of the
circuits and the electric current passing through. the circuits may be subsequently
increased to operate the mechanisms whereby the resistances in the circuits are
changed. This feature of my invention will prevent any alarm being given at the
office in case the mechanism for introducing a different resistance in one circuit
operates before the mechanism in the other circuit operates to introduce a corre-
sponding resistance in the latter circuit, and as it is next to impossible to produce
two mechanisms which will start and operate. absolutely in unison this feature of
my invention is of considerable importance.
The invention also partly consists in the combination in an electric burglar alarm
comprising internal circuits at the office and external circuits extending to, and
through, guarded structures, of galvanometers or differential relay magnets located
at the office and connected with the external circuits for the purpose of giving
alarms, mechanism in the office for successively introducing different resistances
into one of the internal circuits, similar mechanism in each of the external circuits
for successively introducing different resistances into the said circuits, and a
system of switches and connections at the office so arranged that any one of the
galvanometers or differential relay magnets for giving alarms may be switched out
of the circuit in which it is ordinarily operative and into a system of circuits
comprising a supplemental battery, and that the mechanism for introducing'different
resistances into the internal circuit.aforesaid is rendered capable of being used at the
office in connection with any one of the mechanisms, whereby different, resistances
are introduced into the external circuits.
The invention also partly consists in the combination in an electric burglar alarm
comprising internal circuits at the office, and external circuits extending to and
through guarded structures, of galvanometers or 'differential relay magnets located
at the office and connected with the external circuits for the purpose of giving
alarms, mechanism arranged in one of the internal circuits and comprising a train
of wheels. and a controlling electro-magnet whereby different resistances may be
introduced into this internal circuit, a number of rheostats arranged in the other
internal circuits and comprising coils of different resistances, mechanism arranged

page_text: in each of the external circuits and comprising a train of wheels operating under
control of an electro-magnet for introducing different resistances into the said
external circuits, and a system of switches and connections at the office whereby
the internal circuit at the office which is provided with the train of wheels and
resistances may be temporarily connected with any of the external circuits and
subsequently replaced by one of the internal circuits which are provided with
rheostats. I am thus enabled to use a single mechanism comprising a train of
wheels controlled by an electro-magnet in the office in conjunction with a number
of such mechanisms in external circuits.
The invention also comprises a switch consisting of a rocking or rotary block of
insulating material provided with metal plates and a number of metal springs or
spring fingers impinging against the said block and its plates. This switch is very
advantageous as a number of circuit changes may be made by it in a single
movement of its block.
The invention also partly consists in the combination in an electric burglar
alarm comprising an internal circuit and an external circuit, of mechanism at a
guarded structure whereby a number of different resistances may be successively
introduced into the external circuit by increasing at the office the electric current
passing through the circuits, mechanism at the office whereby on the increasing of
the electric current a number of corresponding resistances will be introduced into
the internal circuit, a galvanometer or differential relay. magnet located at the
office and serving to give an alarm there in case the external circuit is tampered
with in an attempt to gain access to a guarded structure, mechanism in the
external circuit which, if short circuited in an attempt to gain access to a guarded
structure will be maintained short circuited, an electro-magnet having a polarized
armature, connections, and two batteries adapted to send electric currents in
different directions over the circuit, whereby the said short-circuiting inechanism.
may be shunted out of the circuit by a watchman at the office so as to be rendered
temporarily inoperative.
The invention also partly consists in the combination in an electric-burglar
alarm, of an external circuit a galvanometer or analogous device, a battery for
supplying an electric current to said circuit and electro-magnetic mechanism for
giving an alarm in the event of the said battery becoming inoperative.
The invention also partly consists in the combination with the local alarining
circuit, of an alarm apparatus of two batteries, a circuit.comprising the local
alarming circuit aforesaid and connecting the positive poles of the said batteries
together and their negative poles together, a conductor common to both batteries,
a periodical interrupter for the common conductor, an electric alarming device to
which the said common conductor leads, electro-magnets arranged one in a portion
of the circuit between the alarming. device and the one battery, and the other
between the alarming device and the other battery, and branch connections
whereby the said electro-magnet may shunt out the alarming device when both
batteries are operative and the common conductor is closed.
HASELTINE, LAKE & Co.,
For the Applicant.

page_text: Improvements in and relating to Electric Burglar-alarms.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co, Patent Agents,
Southampton Buildings, in the County of Middlesex do hereby declare the nature
of invention for "IMPROVEMENTS IN AND RELATING TO ELECTRIC BURGLAR-
ALARMS and in what manner the same is to be performed, to be particularly.
described and ascertained in and by the following statement:
"
This improvement relates to electric burglar alarms of the kind wherein electric
circuits extend between a number of buildings which I shall herein refer to as
guarded structures, and an office where watchmen are kept; means being employed
to indicate at the office any attempt which may be made to gain access to the
guarded structures.
:
An important object of the improvement is to more effectually preclude the
tampering with the electric circuits aforesaid in such manner as to interfere with
the transinission of an alarm to the office on any attempt to gain access to a
guarded structure being made.
In order to facilitate a clear understanding of my improvement I shall designate
the circuits within the office as internal circuits and the circuits extending to and
through the guarded structures as external circuits.
My improvement involves the combination in an electric burglar alarm com-
prising an internal circuit and an external circuit, of a galvanoineter or differential
relay magnet located in the office, having one coil included in the internal circuit,
the other coil included in the external circuit, and each being adapted to affect the
galvanometer or differential relay magnet differently and such resistances in the
internal circuit and the external circuit that the action of an electric current
passing through the two circuits will hold, the galvanometer or differential relay
magnet normally in equilibrium. Any variation of resistance in the external
circuit occasioned by the opening of the door or window will effect the operation
cf means whereby an alarm will be given at the office.
The improvement also consists in the combination in an electric, burglar alarm
comprising an internal circuit and an external circuit, of a mechanism at a guarded
structure whereby a number of different resistances may be successively thrown into
the external circuit by means of increasing at the office the electric current passing
through the circuits, a mechanism at the office whereby on the increasing of the
electric current a number of corresponding resistances will be thrown into the
internal circuit and means located at the office and serving to give an alarm there
in case the external circuit is tampered with in an attempt to gain access to the
guarded structure. By this feature of my improvement the resistances of the
several external circuits extending to and through guarded structures may, by
a watchman at the office, be from time to time changed without occasioning the
sounding of any alarm at 'the office. Obviously the burglar aların will thus be
rendered incalculably more safe because even if burglars should, by the treachery
of a clerk or servant employed at a guarded structure or otherwise, ascertain the
amount of resistance in the structure at the time the same is closed they cannot
rely on the amount of resistance being the same when the attempt to gain access to

page_text: Die Structure is made, and furthermore because even if the resistance which is in
the external circuit at the time of the commencement of an effort to gain access
to the structure is known the change of resistance attempted to, be made a few:
minutes later by a watchman at the office will indicate the burglars' presence and
render their knowledge useless.
The improvement also consists in the combination in an electric burglar alarm
comprising an internal circuit and an external circuit, of a mechanism at a guarded
structure, and a mechanism at the office whereby corresponding resistances may be
successively thrown into the external and internal circuits by means of an increase
of the electric current passing through the circuits, effected at the office, and a
galvanometer or differential relay magnet located at the office and serving to give
an alarm there in case the equilibrium of the resistances in the external and
internal circuits is disturbed by an attempt to gain access to the guarded structure
and a compound key located at the office whereby the galvanometer or differential
relay magnet employed for causing the sounding of an alarm may be cut out of the
circuits and the electric current passing through the circuits may be subsequently
increased to operate the mechanisms whereby the resistances in the circuits are
changed. This feature of my improvement will prevent any alarm being given at
the office in case the mechanism for introducing a different resistance in one circuit
operates before the mechanism in the other circuit operates to introduce a corre
sponding resistance in the latter circuit and as it is next to impossible to produce
two mechanisms which will start and operate absolutely in unison this feature of
my improvement is of considerable importance.
The improvement also consists in the combination in an electric burglar alarm
comprising internal circuits at the office, external circuits extending to and through
guarded structures, of galvanometers or differential relay magnets located at the
office and connected with the external circuits for the purpose of giving alarms, a
mechanism in the office for successively introducing different resistances into one of
the internal circuits, a similar mechanism in each of the external circuits for
successively introducing different resistances into the said circuits, a system of
switches and connections at the office so arranged that any one of the galvano-
meters or differential relay magnets for giving alarms may be switched out of the
circuit in which it is ordinarily operative and into a system of circuits comprising
a supplemental battery, and the mechanism for introducing different resistances
into the internal circuit aforesaid is rendered capable of being used at the office in
connection with any one of the mechanisins whereby different resistances are
introduced into the external circuits.
The improvement also consists in the combination in an electric burglar alarm
comprising internal circuits at the office, and external circuits extending to and
through guarded structures, of galvanometers or differential relay magnets located
at the office and connected with the external circuits for the purpose of giving
alarms, a mechanism arranged in one of the internal circuits and comprising a train
of wheels and a controlling electro magnet whereby different resistances may be
introduced into this internal circuit, a number of rheostats arranged in the other
internal circuits and comprising coils of different resistances, a mechanisin arranged
in each of the external circuits and comprising a train of wheels operating under
control of an electro magnet for introducing different resistances into the said
external circuits, and a system of switches and connections at the office whereby
the internal circuit at the office which is provided with the train of wheels and
resistances may be temporarily connected with any of the external circuits and
subsequently replaced by one of the internal circuits which are provided with
rheostats. I am thus enabled to use, a single mechanism comprising a train of
wheels controlled by an electro-magnet in the office in conjunction with a number
of such mechanisms in external circuits.
The improvement also involves a switch consisting of a rocking or rotary block
of insulating material provided with metal plates and a number of metal springs or

page_text: spring fingers impinging against the said block and its plates. This switch is very
advantageous as a number of circuit changes may be made by it in a single move-
ment of its block.
The improvement also consists in the combination in an electric burglar alarm
comprising an internal circuit and an external circuit, of a mechanism at a guarded
structure whereby a number of different resistances may be successively introduced
into the external circuit by increasing at the office the electric current passing
through the circuits, a mechanism at the office whereby on the increasing of the
electric current a number of corresponding resistances will be introduced into the
internal circuit, a galvanometer or differential relay magnet located at the office
and serving to give an alarm there in case the external circuit is tampered with in
an attempt to gain access to a guarded structure, a mechanism in the external
circuit which, if short circuited in an attempt to gain access to a guarded structure
will be maintained short circuited an electro magnet having a polarized armature,
connections and two batteries adapted to send electric currents in different directions
over the circuit whereby the said short circuiting mechanism may be shunted out
of the circuit by a watchman at the office so as to be rendered temporarily
inoperative.
The improvement also consists in the combination in an electric burglar alarm,
of an external circuit, a galvanometer or analogous device, a battery for supplying
an electric current to said circuit and an electro magnetic mechanism for giving an
alarm in the event of the said battery becoming inoperative.
The improvement also consists in the combination with the local alarming circuit,
of an alarm apparatus of two batteries, a circuit comprising the local alarming
circuit aforesaid and connecting the positive poles of the said batteries together and
their negative poles together, a conductor common to both batteries, a periodical
interrupter for the common conductor, an electric alarming device to which the
said common conductor leads, electro-magnets arranged one in a portion of the
circuit between the alarming device and the one battery, and the other between
the alarming device and the other battery, and branch connections whereby the
said electro-magnet may shunt out the alarming device when both batteries are
opérative and the common conductor is closed.
Figure 1 in the accompanying drawings is a diagram illustrative of a burglar
alarm embodying certain features of my improvement. Figure 2 is a diagram
illustrating a burglar alarm embodying the improvement in a somewhat different
form. Figure 3 is an enlarged plan view of a mechanism for introducing different
resistances into the internal circuit. Figure 4 is a sectional side elevation of what
I term a short circuiting mechanism employed in the burglar alarm. Figure 5 is-
an end view of a switch which is employed in the form of burglar alarm which is
illustrated in Figure 2. Figure 6 is an enlarged edge view of a key-board employed
in the burglar alarm.
I will first describe the form of burglar alarm illustrated in Figure 1. A, A¹, A³
designate a galvonometer comprising two coils A, A¹, which are preferably of equal
resistance and tend to deflect a needle A' in different directions. When an electric
current passing through the coil A, preponderates over an electric current passing
through the coil A¹, the needle will be deflected to the left, and when an electric
.current passing through the coil A' preponderates over an electric current passing
through the coil A the needle will be deflected to the right. In either case the
needle will move against a contact piece and close a local circuit W, W, W which
extends to the pivot of the needle and to contact points with which the needle
operates. This local circuit is provided with a local battery U₁, and an electro-
magnetic-bell X. An audible alarm will be given whenever the galvanometer
needle closes the local circuit. The needle by its vibrations gives a visual alarm.
The circuit which passes through the coil A of the galvanometer is the one which
I designate as the internal circuit, and the one passing through the coil A¹ is that
which I designate as the external circuit. The galvanometer needle will vibrate

page_text: only when the resistance between the two circuits is different and while the resist
ance in the two circuits are in equilibrium the needle will be held midway between
the contact pieces of the local circuit.
The main electric circuit extends from a battery B along a wire C. This wire is
interrupted and connected to the coils of an electro magnet O, the purpose of
which will be presently described. From the electro magnet O the said wire
extends to a metallic contact piece e which is made in the form. of a keeper for a
metallic key E. Thence the circuit extends along the wire C¹ to the coil A of the.
galvanometer, thence through the said coil and along the wire C² to a resistance
coil C and thence along a wire C to a metallic finger on a shaft a comprised in a
mechanism F for introducing different resistances into the internal circuit. From
this shaft a the circuit is continued to one of a number of metallic springs b, b', etc,
comprised in said mechanism F thence to one of a number of resistance coils c c¹ etc.
comprised in said mechanisin, thence along a wire G which connects the said
resistance coils c, c¹, etc. with a metallic key E¹ thence along this key to a contact
piece e which is made in the form of a keeper therefor, and thence by a wire G' to
the battery B. The wire G¹, near where it connects with the battery B, is connected
by a wire C³ to an earth plate H.
The electric current divides at the point where the wire C connects with the
coil A of the galvanometer. Part of the electric current passes through the coil A
and thence along the line C2. Another part of the electric current passes along a
wire C extending from the wire C¹ to the coil A¹ of the galvanometer and thence
through the coil A¹ and to a wire I forming part of the external circuit.
The wire I is connected to one end of the coils of an electro magnet Q having a
polarized armature Q. The object of this electro magnet and its appurtenances
I will describe fully hereafter. From the other end of the coils of this electro
magnet a wire 11 extends to a binding post q of a short circuiting mechanism
R, R', etc. the purpose of which will be explained presently. A wire 12 extends
from a binding post q¹ of the short circuiting mechanism to the contact piece f¹ of
a pair of metallic contact pieces ff' forming a circuit closer on an electric
envelope J designed to enclose a safe in a guarded structure. The contact piece f
is affixed to the body of the envelope J and the contact piece f' is affixed to the
door of the envelope. The contact piece f¹ may be made in the form of a hook
having the shank bent around into a curve which is concentric with the pintles of
the hinges by which the door is connected to the body of the envelope, hence when
the door is closed the hook-like end of the contact piece f¹ will be separated from
the contact piece f, and when the door is opened the hook-like end of the contact
piece f will impinge against the contact piece f. From the wire 12 or the contact
piece a wire Is extends to the coils of an electro-magnet d comprised in a
mechanism F¹ whereby different resistances are introduced into the external
circuit. From the coils of the electro-magnet d the external circuit extends along
a wire I to a metallic finger on the shaft a of the mechanism Fi just mentioned.
Thence the external circuit extends to one of a series of metallic springs b, b¹, etc.
comprised in this mechanism with which the said finger of the shaft a may be in
contact, thence to one of a number of resistance coils c, c¹, etc comprised in the
mechanism F and thence along a wire K. This wire K extends from these
resistance coils c c etc. to the contact piece f of the electric envelope J and thence
to an earth plate H. The circuit is completed to the battery B through the earth
from the earth plate H¹ to the earth-plate H.
C designates a wire leading from a swith C. This switch C has two contact
pieces with which batteries B', B³, are connected by suitable wires. These batteries
B, B are intended to be of equal strength but they are capable of producing
electric currents in opposite directions through the switch C19 and thence to the
wires in circuit with it. These batteries are of greater potential than the battery B.
These batteries B¹, B³, are connected by wires with an earth plate H².
The object
of providing for sending an electric current in reverse directions over the switch C19
will appear later. The wire Q extends to a contact piece 2 arranged below a

page_text: metallic key E2 which normally is out of contact with this contact piece and in
contact, with a keeper e3 which is not in the electric circuit. A wire C17 extends
from the metallic key E to the coils of the electro magnet d of the mechanism F
. whereby different resistances are introduced into the internal circuit. The other
end of the coils of the electro-magnet d is connected by a wire L to the wire I of
the external circuit.
I may here remark that the keys E and E¹ are normally in contact with the
contact pieces e e¹ which constitute their keepers. The key E has a cross bar g of
insulating material which is adapted to impinge against the keys E¹ E2 so that
these keys E¹ E' may be depressed by depressing the key E. These keys are in
effect a single compound key. The key E may be depressed by clock work
periodically if desirable.
Each of the mechanisms F F comprises a train of gear wheels h which have com-
bined with them a weight or a spring whereby they are caused to rotate. These
wheels also have combined with them a retarding device such as a fly j for pre-
venting them from rotating too rapidly. The springs b, b¹ etc. are arranged upon a
circular disk of insulating k so that their ends will project in the way of the metallic
finger of the shaft. a. The rotation of the wheels is controlled by means of a lever
connected to the armature of the electro magnet d and acting in conjunction with
When the electro
a pin m'on a wheel h¹ comprised in the train of gear wheels h.
magnet dis energized the armature is attracted and the train of gear-wheels
permitted to rotate. The resistance of the coils of the electro magnet d is such
that. the electric current from the battery B will not energize it sufficiently to
enable it to attract its armature. It is only rendered operative when the battery B¹
or B is put in circuit by depressing the key E' upon the contact piece e² which is
only done momentarily to effect the release of the train of wheels . The wheels,
when released, therefore, run only long enough for the wheel h¹ to make a single
complete rotation and be arrested again by the lever 7. This is only long enough
for the metallic finger of the shaft a to move from one to another of the metallic
springs b, b¹ etc.
The resistance coils c c¹ etc. are severally made of different resistances and those
of the mechanism F are made to correspond in resistance and order of succession
with those of the mechanism F¹. The resistance coil C³ is placed in the internal
circuit to equalize the resistance which would otherwise exist in the external
circuit over and above the resistance of the internal circuit, owing to the greater
length of wire in the external circuit and the presence of the electro magnet Q
and the electro magnet d of the mechanism F¹ normally in the external circuit.
The key E is allowed to rise above the level of the other keys E¹ E owing to
its keeper e being higher. When the key E is depressed contact is broken between
it and its keeper e and subsequently the other keys are depressed so that they will
break contact with their keepers and the key E' will impinge on its contact piece e².
Owing to this, the battery B is first cut out of circuit next the communication of
the key E through the wires G C³ with the earth plate H is broken, and finally
the battery B¹ or B5 is brought into circuit with the key E. Were it not for
breaking the communication of the key E¹, through the wires GC with the earth
plate H prior to the bringing of the battery B' or B³ into circuit, the electric
current of the battery B¹ might pass along the wire I, thence along the coils of the
galvanometer A A¹ A³, thence along the wire C to the mechanism F and thence
by the wire G key E' and wires G¹, C5, to the earth plate H. This would be
objectionable because it would cause a deflection of the galvanometer needle.
When the keys E E¹ E' have been depressed as described the electric current
from the battery B¹ or B5 will pass to the key E2, thence along the wire C to the
coils of the electro magnet d of the mechanism F, thence along the wire L to the
wire I along the wire I to the electro magnet Q, thence along the wire 11 to
the binding post q of the short circuiting mechanism R R etc thence from the
binding post q of the short circuiting mechanism to the wire I2 and along the
latter to the contact piece f¹ of the electric envelope J, thence along the wire 1³ to

page_text: the electro magnet d of the mechanism F¹, thence along the wire I to the finger
of the shaft a of the mechanism F1, thence to whichever one of the springs b b¹ etc.
of the mechanism F' the finger of the shaft a of said mechanism F may happen
to be in contact with, thence to the corresponding resistance coil c c etc. of the
mechanism F1, and thence along the wire K to the contact piece f and the earth
plate H.
The trains of wheels comprised in the mechanisms F, F¹, will then be released
because the electro magnets & will then attract their armatures and thereby cause
the armature levers to release the wheels h¹. As explained before the keys E E' E'
will only be kept in their depressed positions momentarily so as to enable such of
the resistance coils c c¹ etc. as were in circuit to be cut out of circuit and other of
these coils to be introduced into circuit.
When the keys E E¹ Es are allowed to rise to their normal positions the key E¹
breaks. contact with its contact point e² and cuts off the battery B¹, the key. E¹
rises to its keeper e¹ and the key E rises to its keeper e and establishes communi-
cation between the latter and the battery B. As the battery B is, by the above
described operation of the keys E'E' E, cut off from both coils of the galvanometer
before the resistance in the circuits is changed and is not reinstated in the circuit
until after the charge of resistance in the circuits has been made the galvanometer
needle A will not be affected even if a resistance coil be introduced by the
mechanism in one circuit with greater alacrity 'than by the mechanism in the other
circuit.
It is obvious that by frequently changing the resistances in the circuits it is
made practically impossible for a burglar to effect an entrance into the guarded
structure without giving an alarm at the office even though he happened to learn
what resistance was in circuit at any particular time.
In this example of my improvement a separate mechanism F and set of
keys E E E needs to be employed in the office for each guarded structure. While
I have represented the burglar alarm in connection with but one guarded structure
I intend to use it in connection with a number of guarded structures and one
office.
It is hardly necessary to remark that if the battery B should become inoperative
the whole efficiency of the burglar alarm would be impaired because the galvano-
meter needle would not be deflected and hence no alarms would be given at the
office even if the internal or external circuit were severed. It is therefore very
desirable to provide means for indicating such an accident. I will now describe a
contrivance designed to secure that end.
I have already explained that the wire C is connected to the coils of the electro
magnet O. It will be understood, therefore, that the electric current from the
battery B passes along the coils of the electro magnet O. From there it extends
along the wire C to the keeper e.of the key E. The electro magnet O has an
armature O¹ shown as pivoted in place at one end and adapted to swing towards
and from the electro magnet. It is drawn towards the electro magnet by the force
of the latter so long as the battery B is in working order, but if anything happens
to impair the working of this battery a spring O' will move the armature away
from the electro magnet. When this occurs a contact piece with which the armature
is provided will be moved into contact with a contact piece Os comprised in a local
electric circuit r. The other end of this electric circuit is connected with the
armature O¹. In the electric circuit is a battery B³ and an electro magnetic-
bell Whenever the electric circuit is closed the electro magnetic bell is
sounded and in that way an alarm is given as to the failure of the battery B to
work.
I will now describe the modification of my improvement shown in Figure 2
premising that the same illustrates the improvement in conjunction with two
guarded structures. Here one mechanism F and a single set of keys E E' E' in the
office similar to the mechanism F and the keys E E E² in Figure 1 heretofore

page_text: '
described will suffice for use in conjunction with mechanisms F¹ in several guarded
structures made like the mechanism F' before explained.
M designates a switch located in the office and consisting of a cylinder or block p
of wood or other non-conducting material having at the ends journals mounted in
bearings permitting it to be adjusted axially in either of two positions. Upon the
face of this block are metallic plates n¹ n² n³ n' n³ n°. A number of springs o' 02 03
04.08 08 07 08 00 010 extending from the base piece p² of the switch bear on the face of
the block p. The arrangement of the metallic plates will be made clear hereafter.
N.designates a rheostat composed of a number of resistance coils corresponding
to the resistance coils c c¹ etc. of the mechanisms F F¹ and arranged in the same
order. One end of its coils is connected, by a wire C8 to an earth plate H.
A wire C leading from the spring o' may be connected with the other end of
either of the coils of this rheostat by fitting a plug with which such wire is
provided into any one of a series of holes in the rheostat.
.
I will assume for the present that the block p of the switch M is turned so that
its handle p will be in an upright position.
An electric battery B2 is connected at one pole with an earth' plate H and at the
other pole with one end of the coil of an electro magnet O. From the other end of
the coil of the electro-magnet the circuit extends along a wire C to the spring o
of the switch M, thence over the metal plate n6 to the spring o° of the switch M,
thence by wire C¹ to the coils A. A¹ of the galvanometer A A¹ A². Part of the
electric current passes through the coil A¹ of the galvanometer to the wire I of
the external circuit and another part of the electric current passes through the
coil A of the galvanometer to the wire C and thence to and through the resistance
coil C³ to the spring of of the switch M. From the spring of this part of the
electric current passes over the plate n to the spring o' of the switch M. Thence
passes. by the wire C7 through the rheostat N and thence by a wire C8 to an earth
plate H. The resistance in the coil of the rheostat along which the current passes
is equal to the resistance in the coil of the mechanism F' which is in the external
circuit through which the current is passing. The resistanco coil of the rheostat
which is in the internal circuit will then balance the resistance coil of the
mechanism F in the guarded structure and the resistance coil C³ will counter-
balance any extra resistance that may exist in the external circuit owing to extra
length of wire and the presence of the coils of the electro magnet Q and the electro
inagnet d of the mechanism F¹ hence there will be no deflection of the galvanometer
needle.
it
If it is desired to change the resistance in the internal and external circuits.
belonging to any guarded structure the block p of the switch M belonging to that
guarded structure is shifted so as to bring its handle p² into a horizontal- position.
This will cause the springs o o to make contact with the metal plate n¹, the
springs o o to make contact with the plate n³, the springs os of to make contact
with the plate n³ the springs 08 09 to make contact with the plate n* and the
springs oo10 to make contact with the block p.. The battery B is thus cut off
from communication with the wire C. A wire C12 extending between the wire C
and the spring o³ is, however, put into communication with a wire C18 which leads
from the spring o¹ to the earth plate H³, and thence the electro-magnet is kept
energiged and no alarm will be sounded by the electro magnetic bell 71. The metal
plate n¹ is so arranged on the block p that it will be brought in contact with the
springs of o² before the springs 09 010 have broken contact with the metal plate n
in order that the electro magnet O will always be kept charged and no alarm will
be given by the bell when the switch block is thus shifted.
The electro magnet O the appurtenances thereof, the circuit r and the electro-
magnetic bell' are the same in construction and function as the correspondingly
lettered parts illustrated in Figure 1.
The communication between the rheostat N and the wire C2 will be cut off
when the switch M is thus manipulated. The electric current will now pass from
a battery B along a wire to the contact piece or keeper e of the key E thence along

page_text: this key to a wire C and thence to the spring of of the switch M. From the
spring of it extends over the plate n' to the spring oº, thence along the wire C¹ to
the coil A of the galvanometer. Here it divides; part passing through the coil A.
and thence along the wire C, and part passing through the coil A' and thence along
the wire I.
+
The electric current which passes to the wire C passes thence to and through
the resistance coil C³, thence further along the wire C to the spring oⓇ thence over
the plate n³ to the spring o³, thence along a wire C to the key E' and thence
to the keeper or contact piece e¹ of the latter. From the keeper or contact piece e¹
of this key E' a wire C extends to the shaft a of the mechanism F. From the
resistance coils c c etc. of this mechanism F a wire G extends to an earth plate H.
The battery B is shown as connected by another wire with the same earth plate H.
From the key E³ a wire C15 extends to the spring o' of the switch M. It will
be borne in mind that when the block of this switch occupies the position last
described the plate n³ establishes communication between the spring o³ and the
spring o. A wire L extends from the spring o* and connects with the wire I.
The contact piece e' of the key E' is connected by a wire C1" with one end of the
coils of the electro magnet d of the mechanism F before mentioned. The other
end of the coils of the said electro magnet d is connected with a switch C" which
is like the switch similarly lettered in Figure 1.
This switch has two contact
pieces connected by wires with batteries B¹ B. These batteries are also connected
with an earth plate H. By shifting the switch on to either of the contact pieces
one or the other of these batteries may be put into communication with the contact
piece e of the key E. When the key E2 is depressed so as to impinge against its
contact piece e it will be put into electrical communication with whichever of the
batteries B or B happens to be connected with the contact piece e² of the said
key. Ordinarily the battery B' will be connected to the contact piece e² of the key
but under certain circumstances, hereafter to be fully discussed the battery B³ will
be connected to the said contact piece e². Both the batteries B¹ B5 are of the same
size but they are adapted to send electric currents in reverse directions over the .line.
If, while the block of the switch M occupies the position last described, the
key E be momentarily depressed to its full limit, said key will be removed from its
contact piece e and the battery B will be cut out, the key E' will be separated from
its contact piece e¹ and communication cut off between the wirs C and C¹, the
mechanism F and the earth, hence there will no longer be any communication
between the coil A of the galvanometer and the earth.
:
The key E when depressed thus causes the key E2 to make a contact with its
contact piece e. During this contact an electric current will pass from the
battery B¹ or B' through the electro magnet d of the mechanism F, the key E³,
the wire C¹³, the spring o³, the plate n³, and spring o' of the switch M, the wire L
and along the wire I. From thence the electric current will pass to the electro
magnet thence to or past the short circuiting mechanism R, R', etc. thence to
the contact pieces ffl of the electric envelope J and the mechanism F" and to the
earth, all as I have explained in relation to Figure 1.
Both mechanisms F F¹ commence running as soon as the electric current is
caused to flow by the operation of the key E2 and the resistance in the internal
and external circuits is thereby changed. Suppose the mechanisin F 'F' have
stopped with their resistance coils in circuit. This may be ascertained by
looking at the mechanism F in the office. The plug of the wire C will then be
inserted in the rheostat in such hole as to cause the proper coil thereof to be in
circuit. The block p of the switch M is now reversed so as to bring its handle p²
into an upright position. By thus shifting the switch block, the keys E E' Ê²
and the mechanism F will be cut out of the circuit and the battery B², the
appurtenances thereof and the rheostat N will be thrown into circuit.
It will be understood that the change in the resistance has been made without
deflecting the needle of the galvanometer. The resistances in the internal and
external circuits will now be equal.

page_text: I have designated the external circuits for the two guarded structures shown
and the appurtenances of these two external circuits by the same letters of
reference. The foregoing description may be regarded as having related to either.
It will of course be understood that there is an internal circuit in the office for
each external circuit.
.
After the keys E E¹ E' and the mechanism F have been used in conjunction
with one external circuit they may be similarly used with the other; the necessary
initial operation for this purpose being merely to shift the block of the switch M
in such way as to bring its handle into a horizontal position, and the subsequent
operations being exactly as I have already described in connection with the.
guarded structure first considered. The circuits of many guarded structures may
be treated in the same way with the use of the one set of keys E E¹ E2 and the
single mechanism F. It will be seen that the single set of keys E E¹ E2 are
similarly connected with the circuits of the two guarded structures shown. The
circuits for all the guarded structures which will be used with this single set of
keys EEE will be similarly connected with the keys.
I will now give a detailed description of the electro magnet Q having a polarized
armature and the short circuiting mechanisin, as used in the burglar alarm shown
in both figures 1 and 2.
I have already explained that the wire I is connected to one end of the coils of
the electro magnet Q, that a wire I¹ leads from the other end of the coils of this
electro magnet to the binding post q of the short circuiting mechanism, and that a
wire I leads from the binding post q¹ of the short circuiting mechanism to the
contact piece f¹ of the electric envelope J. The armature Q1, of the electro magnet Q
is polarized or, in other words, consists of a permanent magnet. It is fulcrumed
between the ends to a metallic support arranged about midway between the poles
of the electro magnet Q. It can therefore, rock towards either pole of the electro
magnet Q. A wire I extends from the,wire I' to a contact piece Q mounted upon
a suitable support. When the armature Q! is rocked in one direction it impinges
upon the contact piece Q. When rocked in the other direction it is separated
from the contact piece. Q2. A wire I leads from the metallic support of the
armature Q to the wire I' which extends from the binding post q₁ of the short
circuiting mechanism to the contact piece f of the electric envelope J.
When the switch C₁ (see Figures 1 and 2) is in communication with the
battery B' the electro magnet Q will be so energized as to rock its armature Q¹
away from the contact piece Q2. Consequently the electric current from said
battery will pass from the coils of the electro magnet Q to the wire I, thence into
the short circuiting mechanism R, R¹ etc., and thence along the wire I to the
contact piece of the electric envelope J. If however, the switch C9 be put into
communication with the battery B³ the electro magnet Q will be so energized that
it will rock its armature Q' against the contact piece Q. Then the electric current
will pass from the coils of the electro magnet Q to the wire I thence to the wire 15,
and contact piece Q thence along the armature Q1, thence along the metal support
to which the said armature is fulcrumed, and thence along the wire 16 to the
wire I which leads to the contact piece f of the electric envelope J. In such case
the short circuiting mechanism is shunted out. After describing the short circuiting
mechanism I will make clear the object of sometimes thus shunting it.
From the binding screw q with which the wire I¹ is connected, a wire extends
to a circuit breaker, consisting of a resilient metallic strip R¹ secured at or near one
end to the base piece R, and provided with a thumb piece or button 2 whereby it
may be manipulated. This circuit breaker is combined with a keeper R³ consisting
of a metal arm projecting over the circuit breaker so that the latter will, when in
its normal position, maintain a contact with it. This keeper may be pivoted to
the base piece R so that it can be swung aside, out of contact with the circuit
breaker, when desirable to retain the circuit broken for any length of time without
holding the circuit breaker depressed.

page_text: From the keeper R2 a wire R³ extends to an electro magnet R' whence a wire R5
extends to the binding-screw q¹ the wire I' extends to the contact piece f¹ of the
electric envelope J as I have already.explained. From the contact piece f¹ the
wire I³ extends to the coils of the electro magnet d of the mechanism F¹ whereby
different resistances are introduced into the external circuit. From the coil of the
electro magnet da wire I leads to the metallic finger on the shaft a of the
mechanism F¹¹. Thence as I have shown the electric circuit is continued through
one of the springs b b' etc. and one of the coils c etc. of the mechanism F' and
thence along the wire K to the contact piece f and the earth plate H. A wire I'
connects the earth plate H with the binding post q³ of the short circuiting
mechanism.
R6 designates a vibratory armature, arranged in proximity to one end of the
electro magnet R and pivoted to a supporting bracket so that it can be attracted
by the magnet into contact with it, or, when released, may swing away from it.
Extending from the armature R (see particularly Fig. 4) in this instance, above
the same, is an arm R7 of conducting material-such as metal-which, when the
armature is attracted to the electro-magnet, comes in contact with an arm R³ of
conducting material, extending from a post R of conducting. material, erected on
the base piece R.
A wire R10 (see particularly Fig. 2) extends from the armature R6 to the wire R³,
and is fastened, as here shown, in the binding. screw q¹, and another wire R
extends from the post R to the binding-screw q³ connecting there with the wire I'
which leads to the earth plate H¹.
When, the windows and doors of the structure are closed properly the electric
current will enter on the line wire I¹, pass through the circuit breaker R¹,
keeper R and wire R³ to the electro magnet R*. From thence it passes along
wire R³ to wire I' to the contact piece f¹ of the electric envelope J, thence along
the wire I³ and the coils of the electro magnet d comprised in the mechanism F
thence along the wire I to the shafta of the said mechanism F and thence
through a spring b or b¹ etc. and coil c or c¹ etc. to the wire K and along it to the
earth plate H. Then any momentary change in the resistance of. the circuit
outside the structure will cause only a momentary alarm to be given at the office
with which the line wire I communicates.
If however, the electric envelope, be opened, the electric circuit will be short
circuited through the contact points ff and the coil cor c¹ etc. of the mechanism F¹
which was formerly in circuit will be shunted out.
The electro magnet R* must be so constructed and the armature R so adjusted
in respect to its distance from the electro magnet and the strength of the spring
whereby it is to be returned to its normal position that when an electric current is
flowing through one of the coils c c etc. of the mechanism F' from the battery B
said armature will not be attracted; but that when the coil c or c¹ etc. which was
in circuit is shunted out by the opening of the electric envelope, the armature will
be attracted.
Whenever the electric circuit is short circuited through the contact points fƒ¹
and the armature R° attracted to the electro magnet, the electric current will be
short circuited again, this time through the wire R³ to the wire R10, from the
latter to the arm R7 (see particularly Fig. 4) thence to the arm R³, thence through
the post R and wire R to the wire I (see Fig. 2) and to the ground. In con-
sequence of the latter short circuiting the electro magnet will hold the armature,
even if the electric envelope after being. opened be instantly closed again, because
the electric current will take the short circuit, and the galvanometer needle A
will continue to close the local circuit and cause the bell X to sound an alarm
until the existing short circuit is-broken by the operator at the office opening the
line or otherwise, and the release of the armature effected, whereupon the circuit
may be reinstated through a coil c or cetc of the mechanism F, and the
mechanism in the structure to be guarded will be in condition for further use..

page_text: The short alarm given through a momentary change in the resistance of the
electric circuit from any accidental or other cause outside the guarded structure,
and the long continued alarm given through a change in the resistance occasioned
at or in the said structure from short circuiting out a coil c or c¹ etc. of the
mechanism F, may be easily distinguished from each other.
Although not essential I have shown combined with the electro-magnet R* (sec
particularly Fig. 4) an armature R¹² carrying a bammer R¹³ operating a bell R¹
and conveying to inmates of the guarded structure some preconcerted message
from the operator, or notifying them that their attention to the operator is desired.
This armature R¹ is so adjusted in respect to its distance and the force of the
spring whereby it is retracted, that an electric current of sufficient force to cause
the electro magnet to attract the armature R will produce no effect on the
armature R¹. I therefore use the battery B' (see Figs. 1 & 2) when the bell R¹
is to be operated.
1
On the top of the bell I have also shown an arm or pointer R¹ and extending
from the arm R an indicator R16, which, by being in contact with or close
proximity to the pointer or by being swung away therefrom, will indicate whether
the doors and windows of the structure to be guarded are all closed, by showing
whether the electric circuit is short circuited within the structure.
.The object of using the battery B³ as well as the battery B¹ and of employing
in conjunction with said battery B the electro magnet Q having a polarized
armature and the appurtenances of these devices, is to enable a watchman at the
office to shunt the short circuiting mechanism out of circuit and still avail himself
of a powerful battery for operating mechanisms whereby different resistances will be
introduced into circuit.
I will now more fully describe the local circuit which the galvanometer needle
controls.
U₁ (see Figs. 1 & 2) designates. an electric battery of any approved style.
W designates a wire extending from one pole of the battery U¹, to the pivot of
the needle A² of the galvanometer A A'. As here shown this wire W connected
to the positive pole of the battery U¹. A wire W' extends from the other pole of
the battery U to one end of the coils of an electro magnet comprised in an
electro-magnetic bell X. From the other end of the coils of this electro magnet
a wire W extends to the contact points with which the needle of the galvanometer:
operates. The electro magnetic bell may be of any desirable form.
The local circuit of the alarm as before intimated is composed of the wires
W W W The battery U¹ and the electro magnetic bell X are in this local
circuit. This electro magnetic bell X is the device which is relied on for giving.
an alarm when any change occurs in the main circuit. The battery UI that
supplies the electric current for operating the electro magnetic bell X is the one
which I desire to guard, by providing for the sounding of an alarm in the event.
of its becoming inoperative.
U designates an electric battery which is of the same potential as the battery U
The positive pole of the battery U₁ is connected with the positive pole of the
battery U2 by the wire W, a wire Wa leading from the wire W, and a wire W
leading from the wire W³ to the battery U2. The negative pole of the battery U1
is connected with the negative pole. of the battery U by the wire W¹ a wire Y
extending from the wire W₁ to the coils of an electro-magnet X' a wire Y'
extending from the coils of this electro mag X', a wire Y³ extending from the
wire Y to the coils of an electro magnet.X' and a wire Y³ extending from the coils
of the electro magnet X to the battery U³.
Owing to the manner in which the batteries U₁, U₁, are connected they will
be neutralized so that they will produce no magnetic effects while the current of
both batteries is confined to the wires already mentioned:
The electro magnet X is provided with an armature a pivoted at x³ and
retracted from the poles of the electro magnet X¹ by a spring ³ when the said
electro magnet is not energized.

page_text: The electromagnet X³ has an armature x pivoted at ³. This armature is
retracted from the poles of the electro magnet X by a spring a when this electro-
magnet is not energized.
When the armature
°
From the wire Y' a wire Z extends to a contact point Z¹.
of the electro magnet X is attracted by the electro magnet, it will impinge
against the contact point Z. The wire Z will then be in electric communication
with the armature x. From the armature x a wire Z extends to a contact
point Z³. When the armature c¹ of the electro magnet ✗¹ is attracted by the
said electro magnet it impinges against the contact point Z3 and is then in electric
communication with the wire Z. From the armature x¹ a wire Z extends to a
wire Z. The wire Z is connected to one end of the coils of an electro magnet
comprised in an electro magnetic bell X3. The wire Y¹ is connected to the other
end of the coils of the electro-magnet of this electro magnetic bell. This electro
nagnetic bell is of the kind wherein the attraction of the armature by the
electro-magnet effects the closing of a shunt circuit whereby the electro-magnets
are shunted out. This shunt circuit consists of wires y y' leading from the
wires Y¹ Z respectively; the wire being connected to the armature of the
electro magnet, and the wire y being provided with a contact point against
which the armature will impinge when attracted by the electro-magnet. A spring
is employed to retract the armature when the electro magnet is de-energized.
The wire Z extends from the coils of the electro magnet comprised in the
clectro-magnetic bell ✗³ to the metal shaft of a rotary wheel Ze which is also
made of metal. This wheel is one wheel of a train of wheels operated preferably
by a spring or weight and at a comparatively. slow rate of speed. The wheel Z
is provided with a spur z which once in each rotation makes electrical contact with
a metallic finger Z connected with the wire W
During those intervals of time when the spur of the wheel Zo is not in contact
with the metallic finger Z the electric currents produced by the batteries U₁ U*
will neutralize each other because their positive poles will be connected together
and their negative poles will also be connected together. Should the needle of the
galvanometer A A¹ be deflected against either of the contact points, with which
said needle operates the electric current from the battery UI will pass along the
wire W to the galvanometer needle and from the contact point with which the
needle happens to be in contact to and along the wires W1 W2 to the battery.
Whenever the spur of the wheel Z6 makes contact with the metallic finger Z the
electric current from the battery U₁ passes along the wire W to the wire W³, und
thence along this wire to the wire W. The electric current from the battery U¹
as well as that from the battery U¹ passes along the wire W to the metallic
finger Z Both electric currents pass along the inetallic finger Z to the wheel Z
thence along the wire Z³ to the coils of the electro-magnet comprised in the electro
magnetic bell X³. The electric current from the battery Ui proceeds from the
coils of the electro-magnet comprised in the electro inagnetic bell X³ to the wire Y',
thence to the coils of the electro inagnet X', thence to the wire Y, and thence
along the wire W to the said battery. The electric current from the battery U
after reaching the coils of the electro-magnet comprised in the electro-magnetic
bell X³, proceeds thence along the wire Y' to the wire Y, thence through the coils
of the electro-magnet X' to the wire Y' and along the latter to the said battery U".
The electric currents flow in this manner only momentarily at regularly
recurring periods on the contact of the spur of the wheel Z with the metallic
finger Z7.
•
When they thus flow the electro magnet of the electro-magnetic bell X³, and
the electro magnets X¹ X' will attract their armatures. The movement of the
armature of the electro-magnet comprised in the electro-magnetic bell X³ causes a
stroke of the bell to be made and the attraction of the armatures of the electro
magnets X X to the said electro magnets results in the shunting of the clectric
currents from the wire Z to the wire Z whence they proceed to the armature of
the electro magnet ✗¹, thence to the contact point 23 and wire Z, thence along

page_text: the armature of the electro-magnet X³, and thence along the contact point Z¹ and
wire Z, to the wire Y'. Here the electric currents separate as before explained.
The electric current of the battery U₁ proceeds thence to the wire Y¹, along the
Jatter to the coils of the electro magnet X¹, thence to and along the wire Y to the
wire W and thence along the latter to the said battery U¹. The electric current
of the battery U2 proceeds along the wire. Y to the coils of the electro-magnet X³
and thence along the wire Y³ to the said battery U. Owing to the coils of the
electro-magnet comprised in the electro magnetic bell X³ being shunted out in
this manner the electro-magnetic bell will make but a single stroke while both
batteries remain operative, at each contact of the spur of the wheel Z6 with the
metallic finger 27. The sounding of the electro-magnetic bell in this manner
therefore indicates that the batteries are in order.
Should an accident happen to the metallic finger Z' then the electro magnetic
bell X³ will not ring at all, hence a failure of the bell to ring will indicate that the
said finger is out of order.
If the battery U₁ should become inoperative the electro-magnet X', will not be
enorgized so as to attract its armature x¹ hence the electro-magnet comprised in
the electro-magnetic bell X³ will not be shunted out by the action of the electro-
magnet X¹.
Consequently this electro magnetic bell will ring continuously and
thereby indicate that the battery U₁ is out of order.
To recapitulate this feature of my invention relates to a local circuit provided
with a device for giving an alarm or signal when a main circuit is opened, closed
or altered in resistance. The local circuit is part of a larger circuit connecting the
positive poles of two batteries U U together and their negative poles together.
A conductor common to both batteries and consisting of the metallic finger Z' and
the wire Z leads to an electric alarming or signaling device, which, in the present
example is an electro magnetic bell X³. This common conductor has combined
with it a periodical interrupter shown as consisting of the wheel Z and finger Zi.
Electro magnets X₁ and X' are arranged between the alarming or signalling
device X3 and the batteries U₁. U and branch connections ZZ ZZ³ ZA are
• employed to enable the electro magnets X' X² to shunt out the electric signalling
device when both batteries are operative and the common conductor is closed.
Differential relay magnets would be equivalents for the galvanometer A A' A'.
To conduce to clearness I have drawn lines around the parts illustrated by
Figures 1 and 2 which are in the guarded structures and marked these lines with
the words "Guarded Structures." Likewise I have drawn lines around devices
located in the office and marked the same with the word "Office."
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
First. The combination in an electric burglar alarm comprising an internal circuit
and an external circuit, of a mechanism at a guarded structure whereby a number
of different resistances may be successively introduced into the external circuit by
means of increasing at the office the electric current passing through the circuits,
a mechanism at the office whereby on the increasing of the electric current a
number of corresponding resistances will be introduced into the internal circuit,.
and means located at the office serving to give an alarm there in case the external
circuit is tampered with in an attempt to gain access to the guarded structure,"
substantially as specified.
Second. The combination in an electric burglar alarm comprising an internal
circuit and an external circuit, of a mechanism at a guarded structure and a
mechanism at the office whereby correspondingly different resistances may be
successively introduced into the internal and external circuits at the office by
increasing the electric current passing through the circuits, a galvanometer or
differential relay magnet located at the office and serving to give an alarm there
in case the equilibrium of the resistances in the internal and external circuits is

page_text: disturbed by an attempt to gain access to the guarded structure, and a compound
key located at the office whereby the galvanometer or differential relay magnet for
causing the sounding of an alarm may be cut out of the circuits and the electric
current passing through the circuits may be subsequently increased to operate the
mechanism whereby the resistances in the circuits are changed substantially as
Bpecified.
Third. The combination in an electric burglar alarm comprising internal circuits
at the office and external circuits extending to and through guarded structures, of
galvanometer or differential relay magnets located at the office and connected with
the external circuits for the purpose of giving alarms, a mechanism in the office for
successively introducing different resistances into one of the internal circuits, &
similar mechanism in each of the external circuits for successively introducing
different resistances into the said circuits a system of switches and connections at
the office so arranged; that any one of the galvanometers or differential relay
magnets for giving alarms may be switched out of the circuit in which it is
ordinarily operative and into a system of circuits comprising a supplemental
battery, the mechanism for introducing different resistances into the internal
circuit is rendered capable of. being used at the office in connection with any one
of the mechanisms whereby different resistances are introduced into the external
circuits substantially as specified.
Fourth. The combination in an electric burglar alarm comprising. internal
circuits at the office and external circuits extending to and through guarded
structures, of galvanometers or differential relay magnets located at the office and
connected with the external circuits for the purpose of giving alarms, a mechanism
arranged in one of the internal circuits and comprising a train of wheels and a
controlling electro magnet whereby different resistances may be introduced into
this internal circuit, a number of rheostats arranged in the other internal circuits
,and comprising coils of different resistances, a mechanism arranged in each of the
external circuits and comprising a train of wheels operating under control of an
electro-magnet for introducing different resistances into the said external circuits
and a system of switches and connections at the office whereby the internal circuit
at the office which is provided with the train of wheels and resistances may be
temporarily connected with any of the external circuits and subsequently replaced
by one of the internal circuits which are provided with rheostats, substantially as
and for the purpose specified.
Fifth. A switch consisting of a rocking or rotary block of insulating material
provided with metal plates, and a number of metal springs or spring fingers
impinging against the said block and its plates, substantially as specified.
Sixth. The combination in an electric burglar alarm comprising an internal
circuit and an external circuit, of a mechanism 'at a guarded structure whereby
a number of different resistances may be successively introduced into the external
circuit by increasing at the office the electric current passing through the circuits,
a mechanism at the office whereby on the increasing of the electric current, a
number of corresponding resistances will be introduced into the internal circuit,
a galvanometer or differential relay magnet, located at the office and serving to give
an alarm there in case the external circuit is tampered with in an attempt to gain
access to the guarded structure, a mechanism in the external circuit which, if short
circuited in an attempt to gain access to a guarded structure will be maintained
short circuited, an electro-magnet having a polarized armature, connections and two
batteries adapted to send electric currents in different directions over the circuit
whereby the said short circuiting mechanism may be shunted out of the circuit by
a watchman at the office so as to be rendered temporarily inoperative, substantially
as specified.
Seventh. The combination in an electric burglar alarm, of an external circuit, a
galvanometer or analogous device, a battery for supplying'an electric current to the
said circuit and an electro-magnetic mechanism for giving an alarm in the event
of anything happening to the said battery.

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Eighth. The combination with the local alarming circuit, of an alarm apparatus,
of two electric batteries, a circuit comprising the local alarming circuit aforesaid
(and connecting the positive poles of the said batteries together and their negative
'poles together; a conductor common to both batteries, a periodical interrupter for
the common conductor, an electric alarming device to which the said common
conductor leads, electro magnets arranged one in a portion of the circuit between
the alarming device and the one battery, and the other. between, the alarming
device and the other battery, and branch connections whereby the said electro
magnet may shunt out the alarming device when both batteries are operative and
'the common conductor is closed, substantially as specified.
Dated this 97th day of Tun100
HASELTINE, LAKE & Co.,
For the Applicant.