Improvements in Electrical Signalling Apparatus.
Year: 1888

page_text: Date of Application, 31st July, 1888
Complete Specification Left, 30th Apr., 1889-Accepted, 29th June, 1889
PROVISIONAL SPECIFICATION.
[Communicated from abroad by EDWARD DAVIS, Electrician, and EBENEZER BAKER
WELCH, Gentleman, both of Cambridge, Massachusetts, United States of America.]
Improvements in Electrical Signalling Apparatus.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, do hereby declare the nature of
this invention to be as follows:-
My invention, relates to electric signalling apparatus; and more particularly to
contrivances of that kind designed for use in police street signal boxes, and in
similar places for the purpose of giving signals or alarms.
The object of this invention is to provide an apparatus which shall be capable of
giving certain common signals or alarms, such as a signal indicating the number of
the box in which the operator may be calling an ambulance, giving an alarm of fire,
calling to the telephone, or the like and also an individual or particular signal which
shall indicate the particular officer, watchman or person making the signal.
A telegraph-alphabet instrument that is, an instrument capable of recording signs
or marks made by the making and breaking of an electric circuit, and a clock
mechanism, which may be sot in operation and automatically effect the giving of a
predetermined signal or alarm, are employed.
The improvements consist chiefly in the construction of the transmitting instrument
which enables keys or similar devices of different form or character to be employed
each of which when used to set in operation the clock mechanism will give and cause
the receiving instrument to record a different signal.
The receiving instrument may be of any suitable or known construction, for the
convenience of the present description a Morse" instrument adapted to record a
telegraph alphabet of dots and dashes made by the making and breaking of an
electric circuit is employed.
According to the said invention a front or base plate of any suitable material is
provided having a centre plate supported on posts or pillars of hard or vulcanized
rubber or other insulating material; and a back or rear plate, between which and the
centre plate the time mechanism is supported. The time mechanism consists of a
main spring wound on a barrel secured to a main spindle to which is also secured a
toothed wheel engaging with a pinion attached to or forming an integral part of
a centre spindle with which is connected an escapement mechanism of common
construction, consisting of a toothed wheel on the said centre spindle an escapement
lever pivoted to the centre plate and engaging with the said toothed wheel, and a
pendulum; attached to the fulcrum or pivot of the escapement lever.
Another lever, is moreover provided pivoted to the rear face of centre plate and
resting at its free end on a pin or stud upon which it is normally held by a light
spring. The said lover is provided on the rear side toward its inner end with a lug
or offset which lug is adapted in the normal position of the lever, to engage a
forwardly projecting pin on a toothed wheel and stop the rotation of the said wheel.
A ratchet wheel is secured to the inner end of the main spindle; with the teeth of
this ratchet wheel engages a pawl or lever which, when lifted so as to turn the
ratchet wheel the distance of one tooth, will be brought into contact with the lower
end of a pin projecting down from the inner end of the above lever and raise the
said lever so as to permit the said pin to escape from the lug or offset and allow the
centre spindle to make one complete rotation, when the said pin will again come in
contact with the lug or offset and thus stop the operation of the time mechanism.

page_text: The turning of the said ratchet wheel the extent of one tooth is designed to be
sufficient to wind up the main spring far enough to effect one complete rotation of
the centre spindle. A holding pawl is provided for preventing the backward turning
of the ratchet-wheel-and main spindle..
A disc of hard or vulcanized rubber, or other suitable non-conducting material, is
placed on another disc of metal of good conducting properties, which latter disc is
supported on posts of material similar to the last mentioned disc, which posts are
attached to, though insulated from the front plate. The last mentioned disc is
provided with a rim extending up around the periphery of the vulcanized rubber
disc which rim is notched at intervals.
The forward end of the centre spindle rests upon the vulcanized rubber disc and
may have a journal bearing in the same, so that the rim, its disc, and the posts, will
be completely insulated from other parts of the device.
The vulcanized rubber disc is provided for the purpose of insulating the centre
spindle and its adjuncts from the metal disc or part on which the said vulcanized
rubber disc rests.
To the forward end of centre spindle is secured an arm which extends out over
the rim of the vulcanized rubber disc so as to not directly be brought in contact
therewith as the said centre spindle is rotated. The said arın is provided with a
laterally projecting spring, and a contact-finger or piece resting lightly at its free end
on the rear edge of the said rim so that if one pole of an electric circuit were connected
with the posts on the said rim and the other with parts of the device be in electrical
communication with the centre spindle and its arm when the said centre spindle is
rotated once upon its axis the circuit would be made and broken by the said finger
and the herein before described notches in the rim of the vulcanized rubber disc five
times at one point and four times at another point with a short broken interval at a
third point thus causing the receiving instrunient to record, say five dots a space and
four dots indicating fifty four as the number or common signal of the box.
Special or individual signals may moreover be given, in addition to this common
signal, by the same-device.
any
Suitably supported at their upper and lower ends in combination with suitable-bars
insulated from front plate are any suitable number of slide bars. The said slide bars
are provided at their upper ends with small blocks, keys or teeth of suitable
insulating material, which blocks are adapted when the slide bars are raised to be
brought in juxtaposition to the rim of the vulcanized rubber disc and stand out
slightly beyond the rear edge thereof, so that the free end of the contact finger when
the latter is carried around by the hereinbefore mentioned arm and comes in contact
with any of the said blocks keys or teeth will be raised off the said rim and so break
the circuit the same as, when the said finger fell into the notches in the rim of the
vulcanized rubber disc as herein before described. It is by the raising and releasing
of the said slides so as to form different combinations of the blocks false keys or teeth
around the said rim that I am enabled to make the contrivance capable of giving the
special or individual signals mentioned. An inverted U-shaped arm or yoke is
moreover provided, pivoted at its ends, to the sides or ends of a comb-bar, and adapted
at. its upper end to rest against the rear edge or face of suitable slide bars which
latter devices are provided with suitable notches. The cross bar of the yoke is held
against the rear edge of the slide bars by means of springs attached at, their lower
ends to a bale wire secured to, and extending outwardly from the said yoke and at
their upper ends to slide bars there being one such spring to each slide bar. If, now
any slide bar should be raised so as to bring its block key or false tooth into
juxtaposition with the rim of the vulcanized rubber, disc the cross bar would ride
from one of the notches over one tooth and drop into another notch holding the said
slide bar locked in a raised position by the engagement of the said tooth with the
cross bar until a trip finger extending downward. or outward from the end of the
arm upon the centre spindle shall be brought in contact with another finger extending
up from the cross bar of the yoke, which presses the upper end of the said yoke

page_text: outward, disengaging the said cross bar from the said tooth and permitting the
slide bar to be drawn into its normal position by the spring provided for that
purpose.
Various means may be provided for raising the different slide bars for the purpose
of forming various combinations of the blocks keys or false teeth around the rim of
the vulcanized rubber disc for example two levers may be employed each pivoted at
one end to the front plate, and resting at their free ends on dogs secured to crank
pins or studs adapted to turn in bearings in the front plate and having cranks secured
to their forward ends, whereby the said crank pins or studs may be rocked, and so
cause the dogs to operate on suitable levers and thus raise the free ends of the
said levers.
Levers are moreover provided having suitable pins extending into elongated notches
formed in the rear edges of the slide bars so that as one of the said levers is raised the
pins of such lever will engage such slide bars as may have pins extending into the
notches in the same, and raise such slide bars and their attached blocks, keys or false
teeth with the result before explained.
A pawl or lever is connected by means of an insulating block or link with one of
the said slide bars. This slide bar is adapted to be raised each time that the instrument
is operated to give an alarm or signal in order to trip one of the said levers through
the medium of the lever above mentioned as before explained. The slide bar to
which the above lever is pivoted is sometimes provided with a false insulating key
but it may be without any means for affecting the electric circuit through the medium
of the spring finger.
The operation of the apparatus is as follows, that is to say, supposing, that the
various parts are in their normal position, and that an officer or watchman desires to
call to the telephone an attendant at head quarters, one of the hereinbefore described
levers is raised, thus raising also certain of the slide bars and their blocks or false keys,
tripping the other lever and thus setting the device in operation, so that the spring
finger in passing over the keys will first make and break the circuit so as to record
a telephone call at the receiving instrument, and then in passing over the notches or
teeth will, by the making and breaking of the circuit, record the number of the box
from which the signal is given. The lever which is adapted to raise different slide
bars and forin a different combination of false keys around the rim of the vulcanized
rubber disc may be operated to call, for instance, an ambulance, and give the number
of the box; and as many additional levers may be provided for other common calls,
as may be desired or as the capacity of the contrivance may admit.
Each slide bar is adapted to rest at its lower end on a pin or projection provided
upon a pedal lever pivoted to the front plate and provided with a key hole and other
means to receive a suitable key which may be inserted into the said key hole and
turned so that the wards of the said key will engage and raise certain pedal levers
and the slide bars resting thereon, and in this way form still different combinations
of the blocks or false keys and so set the device in operation and give a signal
corresponding to the structure of the particular key employed, it being seen that keys
can readily be formed to give a large number of different signals.
This provision for operating the slide bars by means of a key to give a signal is
designed to enable special or particular signals to be given by an individual in
possession of a key of particular structural character so that, for example, a particular
officer or watchman can, in his rounds operate the different signals to give assurance
that that particular person is or has been at a particular box, or that a particular
person is at a particular box and is in want of a particular thing, as fan ambulance or
the presence of the attendant at head quarters at the telephone, or the like.
The invention may also be employed as a simple telephone call, since the common
signal can be employed to signal "Central Office" and the special signal to give the
number of the telephone caller.
It is obvious that by increasing the number of slide bars and their insulating keys
a practically endless number of combinations of such keys may be formed and the
usefulness of the device extended.

page_text: The term circuit making and closing or breaking devices as herein employed is
meant to identify such means as the spring contact finger or other equivalent means,
and means for actuating the same.
Although I have hereinbefore described a convenient and advantageous method of
carrying the said invention into practice, it is obvious that the construction of the
said apparatus may be somewhat modified without departing from the nature or
spirit of the said invention.
The apparatus may be used for telephone or other lines to indicate whether the
line is or is not in use. To this end the herein before described vulcanized disc may
be connected to "line in" and the contact arm to "line out," so that when even the
spring is in contact with the said disc the said circuit will be closed and a bell will be
sounded.
When used as a police signal the apparatus may be provided with a receiving
telephone and with a transmitter the latter being preferably of the kind known as
the "Blake."
Dated this 21st Inl. 1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Electrical Signalling Apparatus.
1, HENRY HARRIS LAKE, of the firm of Haseltine, Lake and Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention relates to electric signalling apparatus, and particularly to con-
trivances of the kind designed for use in police street signal-boxes and in similar
places for the purpose of giving-signals or alarms.
The object of the invention is to provide an apparatus which shall be capable of
giving certain common signals or alarms-such as a signal indicating the number of
the box in which the operator may be, calling an ambulance, giving an alarm of fire,
calling to the telephone or the like and also an individual or particular signal which
shall indicate the particular officer, watchman, or person making the signal.
The invention comprises the employment of a telegraph-register, that is, an
instrument capable of recording signs or marks made by the making and
breaking of an electric circuit and a clock mechanism, which may be set in
operation and automatically effect the giving of a predetermined signal or alarm.
The improvements chiefly consist in the construction of the transmitting instrument
which enables the employment of keys or similar devices of different form or
character, each of which, when used to set in operation the clock mechanism, will
give and cause the receiving-instrument to record a different signal.
I will now proceed to describe the invention, so that others skilled in the art may
be able to make and use the same, reference being had to the accompanying drawings,
and to the letters of reference marked thereon, the same letters indicating the same
parts wherever they occur.
Figure 1 represents a rear elevation of a signal-transmitting apparatus em-
bodying the said invention, parts of the supporting-frame being pictured as
broken out.
"
'
Figure 2 is a rear elevation of the parts attached directly to the base-plate, the clock
mechanism proper being removed.
Figure 3 is a side elevation of the device complete as shown in figure 1, a portion
of one of the parts being represented as broken away.
Figure 3 is a detail hereinafter referred to.
Figure 4 is a plan view of the pedals or levers for operating the special signal or
pattern slides.

page_text: Figure 5 is a view of a key used in connection with the improvements and
hereinafter referred to.
The receiving instrument may be of any suitable or known construction; for
convenience of the present description a "Morse" instrument adapted to record a
telegraph alphabet of dots and dashes made by the making and breaking of an
electric circuit is employed.
In the drawings, A represents the front or base plate, of any suitable material.
B indicates the centre plate, supported on posts or pillars C, of hard or vulcanized
rubber or other insulating material; and D is the back or rear plate, between which
and the centre plate B, the time mechanism is supported, consisting of a mainspring E,
wound on the barrel F, secured to the main arbor G, to which is also secured the
toothed wheel H, engaging with a pinion I, attached to or forming an integral
part of centre arbor J, with which is connected an escapement mechanism of
common construction, consisting of a toothed wheel K on centre arbor Jan
escapement lever L, pivoted to the centre plate and engaging said toothed
wheel K, and a pendulum M, attached to the fulcrum or pivot of the escapement-
lover.
N represents a lever, pivoted at O to the rear face of centre plate B, and resting
at its free end on a pin or stud P, upon which it is normally held by a light
spring Q. Said lever N is provided, on the rear side toward its inner end, with
a lug or offset R, which lug is adapted, in the normal position of the lever, to
engage a forwardly-projecting pin V, on toothed wheel K, and stop the rotation of
said wheel, as seen in Figure 3.
S represents a ratchet-wheel secured to the inner end of main arbor G, the teeth
of which ratchet-wheel are engaged by a pawl or lever, T, which when lifted
to turn the ratchet-wheel the distance of one tooth, will be brought into contact
with the lower end of a pin U, projecting down from the inner end of lever N,
and raise said lever, so as to permit the pin V to escape from lug or offset R,
and allow the centre arbor J, to make one complete rotation, when pin V will
again come in contact with lug R, and thus stop the operation of the time
mechanism.
The turning of ratchet-wheel S the extent of one tooth is designed to be sufficient
to wind up the mainspring E far enough to effect one complete rotation of the
centre arbor J.
W is a holding-pawl for preventing the backward turning of ratchet-wheel S and
the main arbor G.
a represents a disc of hard or vulcanized rubber or other suitable non-conducting
material, which disc is superincumbent on another disc of metal of good conducting
properties, which latter disc is supported on posts b, b, of material similar to the last-
mentioned disc, which posts are attached to, though insulated from the front plate A.
The last mentioned disc is provided with a rim c, extending up around the periphery
of the disc a, which rim is notched at intervals, as indicated at d, d, Figures 2 and 3.
The forward end of centre arbor J, rests upon disc a, and may have a journal-
bearing in the same, so that rim c, its disc, and posts b b will be completely
insulated from other parts of the device. The purpose of the disc a is to insulate
the centre arbor and its adjuncts from the metal disc or part on which the
disc rests.
To the forward-end of centre arbor J is secured an arm e, which extends out
over rim c, so as to not directly be brought into contact therewith as the centre
arbor is rotated. Said arm is provided with a laterally-projecting spring contact-
finger, resting lightly. at its free end on the rear edge of rim c, so that if one
pole of an electric circuit were connected with posts bb or rim c. as represented
by the "line-in" wire L", and the other with parts of the device in electrical
communication with centre arbor J, and its attached arm e, as represented by the
"line-out" wire L, when said centre arbor is rotated once upon its axis the circuit
would he made and broken by the finger and notches in flange c five times at

page_text: .
the point and four times at the point h, with a short broken interval at
the point, thus causing the receiving-instrument to record, say, five dots, a
space, and four dots, indicating fifty-four as the number or common signal of
the box.
It now only remains for me to explain how special or individual signals may be
given, in addition to this common signal, by the same device.
Suitably supported at their upper and lower ends in comb-bars j, j¹, insulated
from front plate A, are any suitable number of slide-bars k. In the present instance
I have shown five such bars; but in practice I propose, ordinarily, to use a greater
number. Said slide-bars are provided at their upper ends with small blocks or
-keys, or teeth 1, of any suitable insulating material, which blocks are adapted,
when the slide-bars are raised, to be brought in juxtaposition to rim c and stand out
slightly heyond the rear edge thereof, so that the free end of contact-finger, when
the latter is carried around by arm e and comes in contact with any of the blocks 1,
will be raised off of rim c, and so break the circuit the same as when the said finger
fell in the notches of the rim at the points g and h, as herein before explained. It is
by the raising and releasing of the slides k, so as to form different combinations of
the blocks or false teeth 7 around rim c, that I am enabled to make the contrivance
capable of giving the special or individual signals mentioned.
m indicates an inverted-U-shaped arm or yoke, pivoted at its ends, as at m¹, to the
sides or ends of comb-bar j, and adapted at its upper end, as at n, to rest against the
rear edge or face of slide-bars k, which latter devices are notched, as represented
at o o¹. Cross bar or part n of yoke m is held against the rear edge of slide-bars k
by means of springs p, attached at their lower ends to a bail-wire 9, secured to
and extending outwardly from yoke m, and at their upper ends to skde-bars k,
there being one such spring to each slide-bar. If now any slide-bar k should be
, raised so as to bring its block or false tooth l into juxtaposition with rim c, cross-bar n
would ride from notch o' over tooth r and drop into notch o, holding such slide-bar
locked in raised position by the engagement of tooth with cross-bar n until trip-
finger extending-downward-or outward from the end of arm e, shall be brought
in contact with finger n', extending up from cross-bar n of yoke m, and press
the upper end of said yoke outward, disengaging cross-barn from tooth r, and
permitting spring p to draw the slide-bar down to its normal position.
Various means inay be provided for raising different slide-bars & for the purpose
of forming various combinations of the false insulating-teeth around rim c. In the
present instance I have shown two levers ss, each pivoted at one end to the front
plate A, and resting at their free ends on dogs t, secured to crank pins or studs t¹,
adapted to turn in bearings in the front plate, and having cranks t² (shown in dotted
-lines in Figure 2) secured to their forward onds, whereby said crank pins or studs
may he rocked in the direction of the arrows figure 2, and so cause dogs t to operate
on levers s s¹, and raise the free ends of said levers, as represented by the dotted lines
. relating to lever s in Figure 2.
Levers and are provided with pins u, extending into elongated notches v formed
in the rear edges of slide-bars k, so that as levers or s' is raised pins u of such lever
- will engage such slide-bars as may have pins u extending info notches of the
same and raise such slide-bars and their attached false teeth 1, with the result before
explained.
It will be noticed that pawl or lever T is connected by means of an insulating block
or link T, with one of the slide-bars k, and that this slide-bar is adapted to be raised
each time that the instrument is operated to give an alarm or signal, in order to trip
lever N through the. medium of lever T, as before explained. Though I have shown
the slide-bar to which lever T is pivoted as provided with a false insulating key l, it
need not be so equipped, but be without any means for effecting the electric circuit
through the medium of spring-finger f
Supposing, now, that the various parts are in their normal position, which is that
represented. in Figure 1, and that an officer or watchman desires to call to the

page_text: telephone an attendant at headquarters, and 'that levers is designed to make the
telephone-call, said lever will be raised, as represented in dotted lines in Figure 2,
raising certain of the slide-bars and their false keys, as represented, for example, in
said figure, tripping lever N and setting the device in operation, so that spring-
finger f, in passing over keys l, will first make and break the circuit, so as to record a
telephone-call at the receiving-instrument, and then, in passing over notches or
teeth dd, will, by the making and breaking of the circuit, record the number of the
box from which the signal is given. Lever s¹ being adapted to raise different slide-
bars and form a different combination of false keys around rim c, said last
mentioned may be operated to call, for instance, an ambulance and give the number
of the box, and so as many additional levers may be provided for other common calls
as may be desired, or as the capacity of the contrivance 'admit.
may
Each slide-bar is adapted to rest at its lower end on a pin or projection w¹, of a
pedal-lever, W, pivoted at w³ to the front plate provided with a key-hole, and other
means to receive a key y, which may be inserted into the key-hole and turned so
that its wards will engage and raise certain pedal-levers and the slide-bars resting
thereon, and in this way form still different combinations of the false keys around
rim
C,
and so set the device in operation and give a signal corresponding to the
structure of the particular key employed, it being seen that keys can readily be
formed to give a large number of different signals. This provision for operating the
slide-bars by means of a key to give a signal is designed to enable special or particular
signals to be given by an individual in possession of a key of particular structural
character, so that for example, a particular officer or watchman can in his rounds
operate the different signals to give assurance that that particular person is or has
been at a particular box, or that a particular person is at a particular box, and is in
want of a particular thing, as an ambulance or the presence of the attendant at head-
quarters at the telephone, or the like.
The invention may also be employed as a simple telephone call, since the common
signal can be employed to signal "central office" and the special signal to give the
number of the telephone caller.
It is obvious that by increasing the number of slide bars k and their insulating-
keys a practically endless number of combinations of such keys about rim c may be
formed and the usefulness of the device extended.
The operation of the invention as a whole has heen so fully explained in the
description of the construction, relationship, and function of the several groups of
devices as to make further explanation unnecessary.
The torin circuit making and closing or breaking devices or mechanism, as herein
employed, is meant to identify such means as spring contact-finger f, or equivalent
means, and means for actuating the same.
Though I have set forth the particular form and arrangement of the parts com-
prising the invention, as herein represented, it is obvious that these may be varied
without departing from the nature or spirit of the invention.
The apparatus may be used for telephone or other lines to indicate whether the
line is or is not in use. To this end the disc c may be connected to line L";
and the contact-arm to line out L, as shown in Figure 3, so that when even
the spring is in contact with the disc c the circuit will be closed and a bell B¹
will be sounded.
Having now particularly described and ascertained the nature of the said inven-
ciou, and in what manner the same is to be performed, as communicated to me
by my foreign Correspondents, I declare that what I claim is :-
First. In an electrical signalling apparatus, the combination, with the conducting
strip, the movable contact-arm, one or more projections adapted to be moved into
position to cause changes in the relation of the contacts, a catch for holding the
projections in position during the passage of the movable contact-arm over them, and
a projection connected to the movable contact-arm, adapted to co-operate-with .and

page_text: move the catch out of engagement with the projections when the contact-arm has
passed by them, substantially as described.
Second. In an electrical signalling apparatus, the combination, with an electrical
contact having a determinate signal indicated thereon, a travelling contact, and a
motor for moving it over the first mentioned contact, of one or more teeth or pro-
jections arranged to be projected in the path of the travelling contact, a catch for
holding said teeth in projected position, and connections between said catch and
motor, whereby the foriner will be operated by the latter and the teeth or any of
them allowed to return to normal position after the signal has been transmitted, sub-
stantially as described.
Third. In an electrical signalling apparatus, the combination, with a circuit breaker
arranged to transmit a determinate signal and a motor for operating the same, of one
or more teeth or projections arranged to co-operate with the circuit breaker to vary
the signal sent, a catch for holding said teeth in operative position, and connections
between said teeth and the motor for releasing the latter when the former are
placed in operative position, and other connections between said catch and motor for
allowing the return of the teeth to normal position after the transmission of the signal,
substantially as described.
Fourth. In an electrical signalling device, the combination, with the circuit
making and breaking contacts arranged for sending a determinate signal, of one
or more teeth or blocks arranged to co-operate with the circuit making and breaking
contacts to vary the signal sent, and a removable key having portions of its
operating surface arranged to operate one or more of said teeth, so as to vary the
normal signal to correspond with the surface of the key employed, substantially as
described.
Fifth. In an electrical signalling apparatus, the combination, with the circuit
making and breaking contacts, of a series of slide-bars provided with insulating
teeth, severally adjustable within the path of movement of the contacts, so as to
vary the normal operation of the same, and a key y, for moving said bars to adjust
the same, substantially as described.
Sixth. In an electrical signalling apparatus, the combination, with a stationary
contact and a movable contact arranged to transmit a determinate signal of a series
of slide-bars k, provided with teeth 9, adapted to be adjusted. within the path of
the movable contact, pedal levers to, provided with pins or projections w³, and key y,
substantially as described.
Seventh. In an electrical signalling apparatus, the combination with the stationary
contact and the movable contact arranged to transmit a determinate signal of a series
of slide-bars, having notches v, and provided with teeth 1, adapted to be adjusted
within the path of the movable contact, the levers s s', provided with pins u, pedal w,
provided with pins or projections w¹, and key y, substantially as described.
Eighth. In a signalling apparatus, the combination, with the circuit-varying contacts
arranged to transmit a pre-determined signal, of one or more projections arranged
to operate upon the contacts to cause them to vary the signal from the noruial,
and a removable key for co-operating with the said projections to place one or
more of them in position to vary the signal in accordance with the particular key
employed, substantially as described.
Ninth. In a signalling apparatus, the combination, with the circuit-varying
contacts arranged to transmit a predetermined signal, of one or more teeth or
projections arranged to operate upon the contacts to cause them to vary the signal
from the norinal, a catch for holding said teeth in position to cause this variance,
and a removable key for co-operating with said projections to place one or more of
them in position to vary the signal in accordance with the particular key employed,
substantially as described.
Tenth. In a signalling apparatus, the combination, with the circuit-varying contacts
arranged to transmit a predetermined signal and a motor, of one or more teeth or
projections arranged to operate upon the contacts to cause them to vary the signal

page_text: from the normal when projected, a catch for holding said teeth projected and a
projection operated by the motor for releasing said catch when the signal bas
been sent, and a removable key for projecting one or more of the teeth and thus
varying the signal in accordance with the particular key employed, substantially as
described.
Dated this 30th day of Anril 1980
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.