Improvements in Electrical Apparatus for Transmitting and Receiving Predetermined Messages.
Year: 1897

page_text: Date of Application, 11th Dec., 1897
Complete Specification Left, 12th Sept., 1898-Accepted, 15th Oct., 1898
Improvements in Electrical Apparatus for Transmitting and
Receiving Predetermined Messages.
We, SIEMENS BROTHERS & Co. LIMITED, of 12, Queen Anne's Gate, West-
minster, S.W., Electrical Engineers, and CHARLES HOLDEN, of 39, Elmfield Road,
Upper Tooting, S.W., Clerk, do hereby declare the nature of this invention
to be as follows:
-
This invention relates to electrical apparatus for transmitting any of a number
of predetermined messages between a central station and a number of stations
more or less distant.
For instance a number of apartments in a hotel or other establishment might
be arranged to communicate in this way with the office of an attendant, or a
central office might be arranged to communicate with offices at a distance.
For this purpose, the central office is provided with a call bell and fall down or
such like signals, which indicate the room or office which desires to communicate
and also, serve to open the call circuit. It has also a slowly timed make and
break apparatus for sending intermittent electrical currents, and a dial and index
on the spindle of a ratchet wheel having its teeth engaged with an anchor
worked by the armature of an electromagnet in such a manner as to vibrate some-
what slowly. In each apartment or distant office there is also a dial and index,
ratchet wheel, anchor and electro magnet.
The dials have two divided circles the one having marked in the divisions
messages to be sent and the other messages or answers to be received.
When the index stands at zero, a pin on the ratchet wheel holds a spring away
from a contact so that there is no electrical communication with the central office
but when a message has to be sent the operator moves the index to the desired
graduation thus turning the ratchet wheel and withdrawing the pin, so that the
spring makes contact causing the bell to ring at the central station, and the signal
there indicates which apartment or office calls.
The operator at the central station then by pressing one of a number of buttons
marked with the names or numbers of the apartments or offices puts the one that
calls in electrical communication with the make and break apparatus by which
intermittent currents are made to act on the anchor working the ratchet wheel
at the central station and also on that at the apartment or office.
By this both ratchet wheels are turned, the one at the apartment or office back-
wards and the other at the central station forwards until communication is cut off
by the pin at the apartment or office again breaking contact on the index reaching
zero. The index at the central station is thus moved as far forwards as the
distant index had been moved and therefore points to the desired message.
By similar means the official can return an answer to the apartment or distant
office.
The transmitter at each apartment or office can be converted into a receiver by

page_text: turning the index to zero and thereby bringing the pin on the ratchet wheel
above the contact spring, so that the backward movement of the ratchet wheel
does not break the contact; and, by the movement of a switch, the receiver at
the central station can be converted into a transmitter, a pin on the ratchet wheel
being freed from a stop which usually prevents it from moving backwards
beyond zero.
Dated this 11th day of December 1807
Improvements in Electrical Apparatus for Transmitting and
Receiving Predetermined Messages.
We, SIEMENS BROTHERS & Co. LIMITED, of 12, Queen Anne's Gate, West-
minster, S.W., Electrical Engineers, and CHARLES HOLDEN, of 39, Elmfield Road,
Upper Tooting, S.W., Clerk, 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 electrical apparatus for transmitting any of a number
of predetermined messages between a central station and a number of stations
more or less distant.
For instance a number of apartments in a hotel or other establishment might
be arranged to communicate in this way with the office of an attendant, or a
central office might be arranged to communicate with offices at a distance.
For this purpose, the central office is provided with a call bell and fall down or
such like signals, which indicate the room or office which desires to communicate
and also serve to open the call circuit. It has also a slowly timed make and
break apparatus for sending intermittent electrical currents, and a dial and index
on the spindle of a ratchet wheel having its teeth engaged with an anchor
worked by the armature of an electromagnet in such a manner as to vibrate some-
what slowly. In each apartment or distant office there is also a dial and index,
ratchet wheel, anchor and electro magnet.
The dials have two divided circles the one having marked in the divisions
messages to be sent, and the other messages or answers to be received.
When the index stands at zero, a pin on the ratchet wheel holds a spring away
from a contact so that there is no electrical communication with the central office
but when a message has to be sent the operator moves the index to the desired
graduation thus turning the ratchet wheel and withdrawing the pin, so that the
spring makes contact causing the bell to ring at the central station, and the signal
there indicates which apartment or office calls.
The operator at the central station then by pressing one of a number of buttons
marked with the names or numbers of the apartments or offices puts the one that
calls in electrical communication with the make and break apparatus by which
intermittent currents are made to act on the anchor working the ratchet wheel
at the central station and also on that at the apartment or office.
By this both ratchet wheels are turned, the one at the apartment or office back-
wards and the other at the central station forwards until communication is cut off
by the pin at the apartment or office again breaking contact on the index reaching
zero. The index at the central station is thus moved as far forwards as the
distant index had been moved and therefore points to the desired message.

page_text: By similar means the official can return an answer to the apartment or distant
office.
The transmitter at each apartment or office can be converted into a receiver by
turning the index to zero and thereby bringing the pin on the ratchet wheel
above the contact spring, so that the backward movement of the ratchet wheel
does not break the contact; and by the movement of a switch, the receiver at
the central station can be converted into a transmitter, a pin on the ratchet wheel
being freed from a stop which usually prevents it from moving backwards
beyond zero.
The accompanying drawing shews diagrammatically the electrical connections
and the several parts of apparatus for operating as above set forth in a case where,
by way of example, three apartments 1, 2, 3 can communicate with a central
office Č. In each of the three apartments there is a transmitter presenting a
dial D having two sets of circular divisions those of the outer circle marked with
a number of different messages to be sent, those of the inner circle marked with
a number of answers to be received. In front of the dial is an index I which
can be turned in the direction of the arrow so as to point to any one of the
messages to be sent, and on the axis of this index is a ratchet wheel R, having as
many teeth as there are divisions on the dial, its teeth being engaged by an
anchor A which is urged in the one direction by a spring S and in the other direc-
tion by the armature of an electromagnet E. On the wheel R is a pin P which,
when the index I stands at the zero of the dial holds a spring away from a con-
tact B. For convenience of operating a spring plunger F is provided by pushing
down which the anchor A is held disengaged from the wheel R so that the index I
can be freely turned, the depression of F also breaking a contact at G. At the
central station there is also an instrument having a dial with messages and
answers corresponding with D), an index like I, a ratchet wheel R¹, with pin P¹
for contact spring B₁, an anchor A¹ with spring S, an electromagnet E¹ and
plunger F which in this case serves only to hold the anchor A¹ disengaged from
the wheel R' but does not break any contact. There is also at the central station
three indicators H, shewing by the dropping of a screen which of the three
apartments calls. These screens are arranged in the same way as for electric
bells, the screen however as it drops breaking the contact for the current that
acted on it. At the central station there are three switches K, one for each of
the apartments, there is also an electric bell L and battery 1 for it, and a special
relay M with resistance N battery m and switch m¹, the relay being so arranged
that when the switch m¹ is closed it keeps the bell L ringing even after the drop-
ping of the screen H has cut off the current which caused it to drop. This is
effected by the armature when it is attracted down making a double contact at X
which closes the bell circuit and also a circuit of the battery m through the coils
of the relay magnets. Finally at the central station there is a vibrator V con-
sisting of an electromagnet having an armature with spring attached to it so as
to break and make contact at T according as the armature is attracted or not
attracted. In order to render the vibrations of the armature comparatively slow
its end bears upon a lever W of some weight, the inertia of which retards the
movements of the armature.
The several instruments being connected by conductors as shewn, the apparatus
operates as follows:-
:-
A person, say in room 1 depresses his plunger F and turns his index to the
message on his dial which he desires to send. By the movement of the wheel R
the pin P is moved away from the spring allowing it to make contact at B, and
the plunger being released, there is now a closed circuit from one terminal of a
battery Z through the indicator 1 at H, the resistance N, the magnet coils of the
relay to the other terminal of Z, this starts the bell L and causes the screen 1
at H to drop which opens that circuit so that the bell would stop but that the
relay M, the switch m¹ being closed, has closed another local circuit which keeps
the bell ringing until the switch m' is opened. The operator at the central

page_text: station, hearing the bell and seeing that the screen 1 at H has dropped stops the
bell by opening the switch m² and moves the switch 1 at K thus closing a circuit
including the battery Z, the instrument in room 1, the instrument at C and the
vibrator which, by intermittently making contact at T intermittently excites
the electromagnets and E' causing the anchors A and A¹ to vibrate. By the
vibration of A¹ the wheel R' is turned step by step in the direction of the arrow
and at the same time by the vibration of A the wheel R is turned step by step
backwards and this goes on until the index at room 1 returns to zero bringing
the pin P round so as to raise the spring and break contact at B, whereupon the
vibrator stops. As the index of the instrument at C has moved over the same
number of divisions forwards as the index in room 1 has moved backwards, the
index at C necessarily remains pointing to the message to which the index in
room 1 had pointed before its back movement began. In order that the person in
room 1 may get an answer to his message, he turns his index round to a mark a
little before zero bringing the pin P above the spring which now makes contact
with B; also the operator at (turns his index to the division on the inner circle
representing his answer. Thus there being contact both at B and at 13 the cir-
cuit is closed and the vibrator V comes into action moving the index in room 1
backwards and that at C forwards until the pin P comes under the spring and
breaks the contact at B¹, whereupon the vibrator stops, the index in room 1 having
moved backwards as far as that at C has moved forwards, and therefore pointing
to the answer sent from C. The communication having been completed, both
indexes are turned to zero, the screen 1 at H is raised, the switch m¹ is closed and
the switch 1 at K is opened, so that the apparatus is in condition for subsequent
communications.
Having now particularly described and ascertained the nature of this inven-
tion. and in what manner the same is to be performed, we declare that what we
claim is:-
1. Electrical apparatus for transmitting and receiving predetermined messages,
constructed and operating substantially as described with reference to the accom-
panying drawings.
2. In the apparatus referred to in the preceding claim, a transmitting and
receiving instrument comprising a dial with two sets of divisions, an index, a
ratchet wheel on the axis of the index, a pin on the wheel operating on a contact
spring, an electromagnet and a spring anchor worked by its armature to move the
wheel step by step, substantially as described.
3. In the apparatus referred to in Claim 1 a vibrator comprising an electro-
magnet and its armature carrying a contact spring and bearing on a retarding
lever, substantially as described.
4. In the apparatus referred to in Claim 1, in combination with the indicator
screen, and bell, the special relay with its battery and contacts, substantially as
described.
D
1