A Multiplex Selective System of Wireless Telegraphy.
Year: 1899

page_text: Date of Application, 14th Mar., 1899
PROVISIONAL SPECIFICATION.
A Multiplex Selective System of Wireless Telegraphy.
We, BERTRAM COHEN, of 41, Cornwall Road, Westbourne Park, London, W.,
Electrician, and PHILIP HENRY COLE, of 20, Lessing Street, Honor Oak Park,
London, S.E., Electrician, do hereby declare the nature of this invention to be
as follows:-
:-
This invention relates to a multiplex selective system of wireless telegraphy
whereby with a number of stations, any one station may communicate with any
other selected station without interfering with any of the remaining stations,
although the whole of them may be intercommunicating at the same time.
The desired conditions are obtained by an arrangement which renders the
transmitting and receiving apparatus at each station in condition to send or detect
Hertzian waves for a minute interval of time, every station having allotted to
it a successive minute interval, so that with say ten stations there are ten minute
successive intervals and one or more extra intervals for synchronizing purposes,
the whole forming a complete cycle in which each of the ten stations are capable
of sending or receiving, the complete cycle recurring at such a rate that any
station will be able to send or obtain a legible and practically continuous signal.
To obtain these results each station is provided with a transmitting and
receiving apparatus of any type for obtaining and detecting Hertzian waves.
In addition to these at each station is provided a set of keys in connection with
the transmitting coil, there being as many keys as there are stations. These
keys are connected to the transmitting coil successively by means of a commutating
arrangement so that when say number five key is synchronously connected up
at all stations, calling and signal receiving devices are connected up to the
coherer and relay at number five station so as to be capable of working, and at
all the other stations an engaged signal device is connected up.
The commutating devices at all stations are in synchronism, one or more
extra contacts being provided for this purpose as before mentioned.
One form of commutating device we employ consists of as many contacts as
there are stations and one or more for synchronizing purposes, and a revolving
arrangement to make contact with these successively.
The synchronizing apparatus can be worked by an electro-magnetic or other
movement which brings every commutating arrangement into synchronism at
least once in every revolution.
The above arrangement can be revolved by any convenient form of motor.
In establishing communication between districts separated by a long distance,
intervening stations would be provided and messages relayed on to the distant
district by means of the before mentioned commutating arrangement and this
could be carried out ad infinitum.
14L1
Mach 1000
BERTRAM COHEN,
PHILIP HENRY COLE.

page_text: A Multiplex Selective System of Wireless Telegraphy.
We, BERTRAM COHEN, of 41, Cornwall Road, Westbourne Park, London, W.,
Electrician, and PHILIP HENRY COLE, of 20, Lessing Street, Honor Oak Park,
London, S.E., Electrician, 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 a multiplex selective system of wireless telegraphy
whereby with a number of stations, any one station may communicate with any
other selected station without interfering with any of the remaining stations,
although the whole of them may be intercommunicating at the same time.
The desired conditions are obtained by an arrangement which renders the
transmitting and receiving apparatus at each station in condition to send or detect
Hertzian waves for a minute interval of time, every station having allotted to
it a successive minute interval, so that with say ten stations there are ten minute
successive intervals and one or more extra intervals for synchronising purposes,
the whole forming a complete cycle in which each of the ten stations are capable
of sending or receiving, the complete cycle recurring at such a rate that any
station will be able to send or obtain a legible and practically continuous signal.
To obtain these results each station is provided with a transmitting and
receiving apparatus of any type for obtaining and detecting Hertzian waves.
In addition to these at each station is provided a set of keys in connection with
the transmitting coil, there being as many keys as there are stations. These
keys are connected to the transmitting coil successively by means of a commutating
arrangement so that when say number five key is synchronously connected up
at all stations, calling and signal receiving devices are connected up to the
coherer and relay at number five station so as to be capable of working, and at
all the other stations an engaged signal device is connected up.
The commutating devices at all stations are in synchronism, one or more
extra contacts being provided for this purpose as before mentioned.
One form of commutating device we employ consists of as many contacts as
there are stations and one or more for synchronising purposes, and a revolving
arrangement to make contact with these successively.
The synchronising apparatus can be worked by an electro-magnetic or other
movement which brings every commutating arrangement into synchronism at
least once in every revolution.
The above arrangement can be revolved by any convenient form of motor.
In establishing communication between districts separated by a long distance,
intervening stations would be provided and messages relayed on to the distant
district by means of the before mentioned commutating arrangement and this
could be carried out ad infinitum.
In this invention almost any form of successive contact making device or
selector capable of use on a telegraph circuit & not depending on variations in
current direction or strength would effect the desired result.
Two forms of selectors have been found most suitable viz.:
(1) Selector with rolling mercury globules making successive contacts: these
globules released synchronously by an electro magnetic arrangement. Sheet I.
(2) Selector with clockwork driven windmill arms each having a brush, so as
to make successive contacts; the arm being synchronously released by an electro
magnetic arrangement. Sheet II.
On the accompanying drawings Sheet I shows the connections of the complete
system for both the main or synchronising station & the subsidiary or synchronised

page_text: stations, the apparatus remaining the same in each case, only a slight alteration
in connections & details being required as hereafter explained.
The selector shewn on this sheet in the left hand bottom corner is the first
mentioned form & consists of the following parts:-
A mercury containing vessel a terminating in a stop cock b which regulates
the flow of mercury, allowing only a fine stream to flow into chamber c thus
regulating the size of the globule. Valve d allows the globule to fall through
the sloping tube g, the valve d is actuated by armature e held up by spring e¹ &
attracted by electro-magnet f. The sloping tube g is made of an insulating
material and has a common contact running inside connected to terminal h
there are also let in to it a number of equi-distant pin contacts k, etc.; the last
of these contacts 7 is used for synchronising at the main station; it is similiar
to the other contacts but at the sub-stations it is lengthened as shewn by dotted
lines at for reasons hereafter explained.
The sloping tube terminates in a receiving vessel m with draw off tap n. also
air valve which regulates the fall of mercury globule by varying the air
pressure.
The selector at sub stations is fitted with pillar and springs capable of
making contact with armature e as explained hereafter.
A and B are conductors for sending and receiving Hertzian waves respectively.
C and D are induction coil and spark gap for generating waves. F is a condensor
and E is earth.
The receiving conductor B is connected to coherer G through back contacts W
of Morse sending keys H, H, etc., the front & back portions of the arms of the
keys are insulated from each other. The coherer is connected through cell K
and retardation coils L. L' to relay M and is de-cohered continuously by tapper N.
For receiving purposes there is a Morse inker 0 and set of engaged signal
devices P, P etc.
The number of contacts k, etc. should be a multiple of the number of
stations, so that a single globule falling through the tube connects up the
receiving & sending apparatus for each individual station several times. Sheet I
shows apparatus for four stations & the contacts k, etc. are repeated twice.
The method of operating would be as follows: —
The rate of flow of mercury having been adjusted at all stations by means of
air valve o this should rarely require re-adjusting. It is presumed that daily
operations are about to be commenced & the main station sends an ordinary
non-selective message to all sub-stations who thereupon set spring contact s in
connection with small hollow at end of armature e. The valve control magnet f
is thereby connected up through springs and armature e by dotted line connec-
tions X, X, X2 to contacts T of signal relay M (at sub-stations the details and
connections shewn dotted are inserted, and connection from point r of magnet f
to common contact X of keys H, H', etc. is omitted) & thence to battery R, and
back again to the other connection of magnet f.
The main station should give several minutes grace for effecting this & also for
the opening of tap to its usual extent.
The tap regulates the flow of mercury from cisterna into bulb c and is
opened to such an extent that at the usual rate of opening of valve d the bulb c
contains the requisite amount of mercury, this avoids the falling through tube g
of a varying sized globule.
The tap should be furnished with an adjustable stop so that it can always
be open to the same extent.
The main operator should also have opened his tap b.
Everything being ready the main operator depresses the armature e thus
allowing the mercury in c to fall through tube g, and then releases armature
sharply (this part of the operating can be controlled electrically, thus obviating
rapid movement on the part of main operator) the first globule rolls through
tube g connecting, pins etc. successively to common contact h; directly it

page_text: connects synchronising contact / to common contact there is a circuit from / to
one side of valve controlling magnet f and from the other side off to primary of
induction coil C, to battery Rand back to. common contact : thereupon a
fresh globule is started at & simultaneously a wave is sent to all stations which
travelling at the speed of light closes contacts T of signal relays M.
Armatures e at sub stations are thereupon attracted and thus globules of
mercury are released simultaneously at all stations and contact springs at sub
stations flies back to position shewn s¹.
We now follow out the action of second globule released at main station,
directly this touches it starts a fresh globule and sends a further wave which
to distinguish it from a signalling wave we call a synchronising wave.
At sub stations the elongated part of contact 7 shewn by dotted lines is
connected through magnet f, contacts T, of signal relay M. battery R, common
contact and through globule back to 7.
It has been shown that all globules start at simultaneously at all stations
and as contact 7 is spread out, if the rate at which the globules roll, varies in the
slightest the error is corrected at every drop or impulse.
If for any reason a sub station is stopped it can easily be started again after a
few trials by setting springs, as after being released by wave armature e will
only continue working if the wave that released was the synchronising one.
When say number two station is sending to number one the engaged signal
device for number one will show engaged at all other stations, and number
one station must depress number two's key occasionally between words to engage
number two's signal device P₁ at all stations.
It has been found advisable in order to simplify the apparatus to use two
conductors A and B at each station, one B for receiving & the other A for sending.
The back contacts W of Morse keys H, H, etc. are connected in series through
receiving conductor B to coherer G, so that when any one of the Morse
keys H H etc. is depressed, conductor B is disconnected from coherer, the latter
thus not receiving wave from A.
Selector with clockwork driven windmill arm brush, making successive
contacts.
The arm synchronously released by an electro magnetic arrangement. Sheet II.
This selector consists of clockwork a and shaft s, which carries windmill arm
brushes h, and shaft D carrying armature e and escapement d..
Beneath armature e is placed electro magnet f one side of which is connected
to brush and the other sider through battery and primary of induction coil
to the synchronising contact 7.
This will be the connections at main station so that when brush h touches the
synchronising contact. a wave is sent to all the other stations, at which the
electro magnets f will be joined one side p to brush h, & the other side r.
through battery and local circuit of relay to synchronising contact 7, so that on
receipt of synchronising wave, armature e is attracted and a fresh impulse given
to windmill arms h.
The method of operating would only vary in a few of the minor details with
whatever selector is used.
With an ordinary land telegraph service, this system can work well in con-
junction, where large rivers, mountainous or forest land have to be crossed, as
only two stations will be required, one synchronising and the other synchronised.
one on each side of the water or other obstruction and any number of telegraph
lines can be brought in to each station with an electro magnetic relay in each
circuit, so as to automatically transmit the messages through space.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is: -
1. The improved multiplex selective system of wireless telegraphy wherein a

page_text: number of stations are provided with transmitting and receiving apparatus and
a commutating and synchronising apparatus, the latter being adapted by automatic
connecting up and completing in quick succession a single or multiple series of
circuits to place the circuit of the recording and transmitting apparatus of each
station separately in synchronism with one of the others for a minute interval
of time, the equivalent circuit of all other stations in the system being so arranged
in connection with the contacts that the wave received synchronously by the
receiving apparatus thereat at the same moment of time will serve to operate an
indicator instead of the recording apparatus so that messages may be read or sent
by the other stations during the intervals of time allotted to them and which are
as described automatically selected by the particular key operated, all sub-
stantially as and for the purpose set forth.
2. In a multiplex selective system of wireless telegraphy such as described the
use of a commutating or synchronising apparatus adapted to be operated or
driven & kept in synchronism with others by a current caused to flow in its
circuit by a special synchronising wave transmitted from a main station, sub-
stantially as described.
3. The use in a multiplex selective system of wireless telegraphy such as
described of the hereindescribed combination of receiving and transmitting
apparatus and synchronising and recording and indicating apparatus connected
up in circuits and adapted to operate substantially in the manner and for the
purposes set forth.
4. In the improved system of multiplex selective wireless telegraphy the
use and arrangement of circuits in connection with the commutating and syn-
chronising apparatus and controlling contact keys indicators and recording
apparatus all substantially as and for the purposes set forth.
5. The use in a multiplex selective system of wireless telegraphy such as
described of an engaged indicator adapted to be placed in circuit by the contact
closed by the commutating apparatus at the particular moment of time allotted
to the station to which the message is directed and to which the indicator corre-
sponds substantially as described.
6. A commutating and synchronising apparatus for use in a multiplex selective
system of wireless telegraphy comprising a suitably driven number of rotating
arms carrying brushes and adapted to pass over a series of contacts corresponding
to the number of stations in the system with the addition of one or more for
synchronising purposes, the said rotating contacts being released by an escape-
ment operated by an electro magnetic device which in turn is excited by a current
caused to flow in its circuit through the medium of a synchronising wave sent out
from the main station of the system.
7. For use in a multiplex selective system of wireless telegraphy the improved
commutating and synchronising apparatus constructed arranged and adapted to
operate substantially in the manner and for the purposes set forth in reference
to Sheet 2 of the accompanying drawings.
S. The improved multiplex selective system of wireless telegraphy in which
the transmitting and receiving apparatus at each station is arranged to be in a
condition to send or detect Hertzian waves for a minute interval of time, every
station having allotted to it a successive minute interval and one or more intervals
for synchronising purposes, the whole forming a complete and recurring cycle
in which cach of the stations is capable of receiving or sending messages, sub-
stantially as set forth.
1 11
141 1
1000
BERTRAM COHEN.
PHILIP HENRY COLE.