IMPROVEMENTS IN ELECTRICAL SIGNALLING APPARATUS ESPECIALLY INTENDED TO COMMUNICATE THE OUTBREAK OF FIRE
Year: 1882

page_text: LETTERS PATENT to Charles Spratt of Elizabeth Villas Coplestone Road
Peckham in the County of Surrey, for an Invention of "IMPROVEMENTS IN
ELECTRICAL SIGNALLING APPARATUS ESPECIALLY INTENDED TO COMMUNICATE
THE OUTBREAK OF FIRE"
PROVISIONAL SPECIFICATION left by the said Charles Spratt at the Office
of the Commissioners of Patents on the 23rd February 1882.
of
CHARLES SPRATT of Elizabeth Villas, Coplestone Road, Peckham in the County
of Surrey IMPROVEMENTS IN ELECTRICAL SIGNALLING APPARATUS, ESPECIALLY
INTENDED TO COMMUNICATE THE OUTBREAK OF FIRE"
The object of my Invention is to connect a central or district fire station with a
number of outlying "posts," in such manner that from any post the fire call may
be sent to the central station; and so also that the fire men first arriving at the
post may be able to telegraph to the station for assistance if such should be
required or to communicate for any other purpose. The arrangement can also be
applied to houses shops and public buildings.
At the station I provide a receiving instrument of the "step by step" type, the
details of which I will presently describe. At each of the "posts "I provide a
step by step" transmitter also of peculiar construction.
"
The battery is at the station and the line wires pass from the central station to
the nearest post, thence to the next and so on. In the receiving instrument there
is an electro magnet which, each time that the current is completed at either of the
posts, attracts its armature. The armature works an escapement controlling an
escapement wheel. The escapement wheel has an index fixed upon its axis and
the reciprocating motion of the armature causes the index to pass around the dial.
The dial is marked with the letters of the alphabet and some other signs and
on an outer circle with the names of the several "posts" or places. A key is
provided for setting the index to zero, it operates mechanically by causing a
lever to press upon a suitably shaped cam on the same axis with the index.
The first movement of the armature by shifting a small finger or lever closes
a local circuit in which a bell is included and the bell sounds. The zero key also

page_text: acts on this finger to open the circuit at the same time that the index is set.
There is also a plug circuit closed in the local bell circuit and the bell can be
silenced when desired by withdrawing the plug. The battery which works the
whole system is as already stated at the central station, and here also a finger
key is provided which when depressed closes the circuit at the station and takes
the battery off the line and so as herein after explained indications can be given
to the operator at the post.
The transmitting instrument at each "post " consists of a revolving contact
maker with the proper number of contacts to correspond with the receiving
instrument; so that a complete revolution of the transmitting handle or wheel
produces a complete revolution of the index on the dial. Each contact made by
the transmitting instrument closes the circuit momentarily the circuit normally
(or when the instrument is at rest) being open.
This revolving contact maker can either be turned by hand from letter to letter
or it can be geared with a train of wheel work and a spring or falling weight
suitable for rotating it automatically.
Except whilst the instrument is in use by an operator signalling letter by letter,
the contact maker is always to be left geared up with the wheel work.
The arrangement is such that the pulling out of a stop frees the wheel work and
causes the contact maker to revolve the distance required to move the index at the
receiving station until it points to the name of the "post" which signals. Thus
the operator at the central station knows where the fire call comes from. The
wheel work of the transmitter is stopped at the proper point either by electrical
or mechanical mechanism. If electrical an electro-magnet is provided in the
transmitting instrument and when this attracts its armature it throws a pawl or
stop into the teeth of a wheel on the driving train. To bring the electro-magnet
into circuit one of the contact studs may be insulated and only connected through
the coils of the magnet. Or when the revolving contact maker has reached the
position required a cam surface in connection with it may effect the closing of
the circuit through the electro-magnet. As the contact maker ought not to stop
upon the contact the wheel with which the stop pawl engages is not fast on its
axis but is connected by a coiled spring. The wheel has a slotted hole in it
receiving a pin which is carried round with the axis. The spring which is in
tension, forms a yielding link connecting the pin with the wheel, so that the train
can run far enough to again open the circuit after the pawl has engaged.
Or the driving train may be stopped mechanically at the proper place; this may
be effected by the mere dropping of a tooth into a notch formed in a part revolving
with the contact maker. In either case the fire alarm is given simply by drawing
out a "pull" which withdraws the stop pawl or tooth from the wheel or part with
which it engages.
For verbal communication the driving train is thrown out of gear with the
contact maker and the contact maker moved round by hand step by step to the
letters it is desired to transmit.
In one position in which the contact maker can be placed, the circuit is closed
through a galvanometer, the needle of which consequently deflects.
"
At the same time the position of the index at the station will show to the
operator there that he can communicate with the "post which he does by
depressing his key.
Each time that he does this the galvanometer needle will fall back, there being
then no current on the line or through the galvanometer coils; In this way any
prearranged signs may be given and information if necessary conveyed by the
single needle code.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Spratt in the Great Seal Patent Office on the 23rd August
1882.
CHARLES SPRATT of Elizabeth Villas, Coplestone Road, Peckham in the County
of Surrey. " IMPROVEMENTS IN ELECTRICAL SIGNALLING APPARATUS ESPECIALLY
INTENDED TO COMMUNICATE THE OUTBREAK OF FIRE"
The object of my invention is to connect a central or district fire station with a
number of outlying "posts" in such a manner that from any post the fire call may
be sent to the central station, and so also that the firemen first arriving at the post
may be able to telegraph to the station for assistance if such should be required or
to communicate for any other purpose. The arrangement can also be applied to
houses shops and public buildings.
At the station I provide a receiving instrument of the "step by step" type, the
details of which I will prosently describe. At each of the "posts" I provide a
"step by step" transmitter also of peculiar construction.
The battery is at the station and the line wires pass from the central station to
the nearest post, thence to the next and so on.
In the receiving instrument there is an electro magnet which each time that the
current is completed at either of the posts, attracts its armature. The armature
works an escapement controlling an escapement wheel. The escapement wheel
has an index fixed upon its axis and the reciprocating motion of the armature
causes the index to pass around the dial. The dial is marked with the letters of
the alphabet, and some other signs and on an outer circle with the names of the
several "posts" or places. A key is provided for setting the index to zero, it
operates mechanically by causing a lever to press upon a suitably shaped cam on
the same axis with the index.
The first movement of the armature by shifting a small finger or lever closes a
local circuit in which a bell is included and the bell sounds. The zero key also
acts on this finger to open the circuit at the same time that the index is set.
There is also a plug circuit closer in the local bell circuit and the bell can be
silenced when desired by withdrawing the plug. The battery which works the
whole system is as already stated at the central station, and here also a finger key is
provided which when depressed closes the circuit at the station and takes the
battery off the line and so as herein after explained indications can be given to the
operator at the " post."
The transmitting instrument at each "post" consists of a revolving contact
maker with the proper number of contacts to correspond with the receiving
instrument, so that a complete revolution of the transmitting handle or wheel
produces complete revolution of the index on the dial. Each contact made by the
transmitting instrument closes the circuit momentarily the circuit normally (or
when the instrument is at rest) being open.
This revolving contact maker can be turned by hand from letter to letter. The
same revolving contact maker may also be geared with a train of wheel work and
a spring or falling weight suitable for rotating it automatically. I however find it
more convenient to provide a second revolving contact maker to be turned
automatically by the wheel work.
In either case the arrangement is such that the pulling out of a stop frees the
wheel work and causes the contact maker to revolve the distance required to move
the index at the receiving station until it points to the name of the "post" which
signals. Thus the operator at the central station knows where the tire call comes
from

page_text: For verbal communication the contact maker is moved round by hand step by
step to the letters it is desired to transmit.
In one position in which the contact maker can be placed, the circuit is closed
through a galvanometer, the needle of which consequently deflects. At the same
time the position of the index at the station will show to the operator there that
he can communicate with the "post" which he does by depressing his key. Each
time that he does this the galvanometer needle will fall back, there being then no
current on the line or through the galvanometer coils; in this way any prearranged
signs may be given and information conveyed.
In order that my said Invention may be most fully understood and readily carried
into effect I will proceed to describe the Drawings hereunto annoxed.
Figure 1 is a diagram shewing the general arrangement and combination of the
apparatus for connecting a district with a fire station. The instruments at the
station are indicated, also those at four outlying posts.
Figure 2 is a front elevation, partly in section of the step by step receiver at
the station. Figure 3 is a side elevation also partly in section of the same.
Figure 4 is an elevation, partly in section of the instrument at a call post,
Figure, 5 is a plan of the same. Figure 6 illustrates a modification which may be
made in the construction of the instrument at the call post.
In Figure 1 the following parts are indicated, the instruments at the station
consisting of the step by step receiver A, the main battery B, the short circuiting
key C the bell D in a local circuit, the bell battery E, and the plug socket F.
There is also at the station, the testing galvanometer G and the switch H.
At each post there is a rotary circuit closer i, such as in a complete rotation to
carry the index of the step by step receiver completely around the dial. Also
wheel work (not shown in the diagram) which when set free rotates this, or
preferably another like circuit closer and makes contacts sufficient to carry the
index of the step by step receiver from the zero mark to the name of the post.
Also there is a needle indicator k. for receiving signals from the station.
The circuit of the main battery, when closed, may be traced from the battery,
through the coils of the electro magnet in the receiver, out to the posts, and back
from any post at which the circuit is closed, to the battery. The circuit can also
when desired, be closed in the station by the switch H, and then the deflection of
the galvanometer G, will show that the circuit is complete throughout. When the
circuit is completed at either post the operator at the station can nevertheless
take the battery off the external part of the circuit by depressing the key C, this
he does for the purpose of communicating with the post as hereinafter more fully
described.
The local bell circuit is normally open but it is completed by the first movement
of the index of the receiver and remains complete until the index is replaced by
the attendant. The bell can be silenced by removing the plug at F, this is
necessary when communicating from the station to a post.
In Figures 2 and 3 a is the electro magnet of the step by step receiver, and b
is its armature. The armature b is carried upon the shorter arm of a lever pivotted
at 61; the longer arm of the same lever carries an anchor b², which during the to
and fro movements of the armature resulting from the attraction of the magnet
and the reaction of the spring 6s serves to propel the ratchet wheel c.
The wheel c,
has as many teeth as there are signs upon the dial around which it carries the
index c'. this index being mounted upon the axis of the wheel. To give greater
certainty to the movement there is provided on the same axis a ratchet wheel c³.
having double the number of teeth and with this the light spring pawl c³ engages.
b*, is a projection from the armature lever which when the armature is attracted
comes down upon the light lever & and causes it to make contact with the point e.

page_text: The bell circuit is then completed, through the standard d', upon which the lever d
is carried, through the pivot d². of the lever, through the point e and through the
standard e'. which carries the contact point.
f is a finger key which has two duties to perform, viz. to set the index c' to the
zero mark, and simultaneously to sever the contact between the parts d. and e.
It effects the latter by means of the stem f¹. which when the key is depressed
strikes upon the lever d. and raises the end of it by which contact is made, d' is a
small insulated spring serving to retain the lever d. in either of the positions
which it has to assume. 2 is a spring for returning the finger key f. when it is
released. The index c¹ is brought to the zero mark by the following means: -it
is not fixed upon the axis of the wheel c, but is carried upon a tube which embraces
the axis firmly. Upon the tube there is also fixed the heart shaped cam c*. which
the end of the key lever is just able to pass when the cam is in the position indi-
cated in Figure 2 in all other positions the key lever, when depressed, thrusts the
cam round until it assumes this, the zero position.
In these figures the short circuiting key C, the bell D and the plug socket F are
also seen. In Figures 4 and 5, g and h are two insulated springs with which the line
wire is connected and i, and k are two rotary contact making cams in connection
with the return wire. The contact cam i. can be turned round by means of the
jointed handle and the contact cam k, by withdrawing a stop and releasing a
train of wheels as hereinafter described. In either case the projections on the
cam in passing the contact spring, touch it and for each projection a current passes
in the line wire causing the index of the receiver at the station to move a step.
The handle i' has a hemispherical projection on the under side and there are holes
of a like forin arranged in a circle around the handle; these holes each correspond
to a letter or sign and to indicate this letter or sign on the dial of the receiver
the handle is brought to the hole and depressed so that the projection may enter;
thus it is ensured that the handle is brought accurately to the proper place. In
all these positions, excepting one, the projections of the cain are out of contact with
the spring g. The remaining position is that to which the operator sets the handle
when he desires to communicate.
The main circuit is then closed through the contact cam i, the spring g. and
the coils of the needle indicator K, the needle K is consequently deflected, but it
falls back whenever the operator at the station puts down the key C, for the
battery is then taken off from the line. Thus communication is made from the
station to the post. I so wind the coils of the needle indicators K, that at
whichever post the circuit may be closed the resistance to be worked through may
be approximately the same, this I effect by giving a higher resistance to the
indicators, which are near to the station than to those which are more distant, in
such proportion as to compensate for the difference in the lengths of the line
wires. Upon the same axis with the contact cam k there is a barrel upon which
a cord is wound and from this cord the weight m hangs suspended. The barrel
carries a pawl engaging with ratchet teeth upon the side of the contact cam k so
that the weight in descending rotates the contact can. But the barrel can be
turned by a winding key to raise the weight without moving the cam. The barrel
is retained by a pawl n, which a spring n', causes to drop into notches in the
periphery of the barrel. By drawing out the pull o the pawl n can be withdrawn
to free the wheelwork and give the alarm at the station. Then the hook o¹,
attached to the pull draws out the pawl; the pawl however immediately after-
wards escapes from the hook o³ and returns in time to stop the train of wheels
before the next notch passes. of is a spring tending to bring back the pull o. but
usually I provide a small spring bolt not indicated in the Drawings, to retain the
pull until it is freed upon the box being opened by a person in charge.
The side of the box carrying the pull o, opens upon a hinge and as it opens it
withdraws the pawl n thus the attendant with the key can give the call without
having to break the glass q. by which the pull is guarded to prevent improper use
being made of it.

page_text: In order to regulate the speed at which the contact cam k rotates when the
wheelwork is liberated, the cam is geared by toothed wheels and pinions with a
fly, in the arrangement indicated in the drawing the contact cam will give six
contacts each time that it is started before it is again stopped by the pawl n.
but in each post the apparatus will be arranged for a different number of
contacts.
The contact cam k always stops in such a position as to leave the circuit open.
Figure 6 represents a modification which may be made in order to obviate the
necessity for winding up the weight by a separate operation. Here the pull o,
when drawn out operates upon a pawl lever and this engages with a wheel with
notches in its periphery. The axis of this wheel is geared by a wheel and pinion
with the axis of the barrel on which the cord is wound. Each operation of the
pull winds the cord once around the barrel and it and the contact cam kc, make a
completo revolution whilst the weight m. runs down. The contact cam in this
case is furnished with as many projections as there are contacts required to indicate
the post.
Having thus described the nature of my said invention and the manner of
performing the same I would have it understood that I claim :-
First. The combination of apparatus consisting of a step by step receiving
instrument at the station, and a series of posts arranged in succession upon a
çircuit, each post containing an automatic circuit closer, which on being started (by
the drawing out of a stop or by like means) automatically closes and opens the
circuit the number of times required to indicate upon the dial of the receiving
instrument the name of the signalling post substantially as herein described.
Second. The combination of apparatus consisting of a step by step receiving
instrument at the station, and a series of posts arranged in succession upon a
normally open circuit, each post containing an automatic circuit closer which on
being started automatically closes and opens the circuit the number of times
required to indicate upon the dial of the receiving instrument the name of the
signalling post substantially as herein described.
Third. The combination of apparatus consisting of a step by step receiving
instrument and a short circuiting key at the receiving station, and a circuit closer
and needle or indicator at the post, such combination providing the means of
communication from station to post and from post to station, substantially as
herein described.
Fourth. The step by step receiving instrument adapted for a fire station, in
which the call signal causes a bell circuit to be completed by means substantially
as described, and to renain closed until the attendant moves the index of the
instrument back to the zero position.
In witness whereof I the said Charles Spratt have hereunto set my hand and
seal this Fifteenth day of August in the year of our Lord One thousand
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