Improvements in and relating to Telegraphic or Telephonio Call Systems.
Year: 1892

page_text: The decision of the Comptroller-General, of the 30th day of October 1893, allowed,
under Section 18 of the Patents, &c. Act, 1883, an Amendment of this
Specification.
Date of Application, 17th Nov., 1892-Accepted, 31st Dec., 1892
COMPLETE SPECIFICATION (AMENDED).
Improvements in and relating to Telegraphic or Telephonio Call
Systems.
1, HERMANN WETZER of Pfronten Bavaria in the Empire of Germany
Mechanical Engineer 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 any electric circuit comprising a number of stations and
one or more calling stations from which calls are to be sent to any one of the
aforesaid stations and it consists in certain apparatus hereinafter described and
illustrated whereby from any of the calling stations signal may be made at any one
of the receiving stations.
The accompanying drawings illustrate the arrangement in diagram, Figs. 1 and 2
showing slightly modified systems-Figs. 3. 4. 5 and 6 details and further modifica-
tions thereof.
At every receiving station is placed a pendulum P; each of these pendulums
has a different length and consequently a different oscillating period. On each
pendulum P is a lateral arm a which rests against an arm v of the armature A of
an electro magnet E, the said armature being pivoted as at o Fig. 1; or it rests
against a hammer H Fig. 2, in either case in such a way that during the time the
system is at rest the pendulum is supported thereby slightly out of the perpendicular
so that it may more quickly come to rest against this support when the signal ceases
to be transmitted. At every call station is a pendulum P¹ on which is a weight G
moveable so that this period pendulum may be given different rates of oscillation.
When the system is at rest the pendulums P¹ are also at rest being supported out of
the perpendicular against the key t. On the pendulum P' is the contact k.which
when the pendulum is set in oscillation leaves the corresponding contact F and returns
thereto at each oscillation, that is to say either at each double course Figs. 1, 2, 3,
or twice in a double course as at Fig. 5 or Fig. 4.
Where a constant current is employed with a relay at each receiving station, the
contacts F and k are placed in the circuit L. When any station is to be signalled
to the operator at the calling station sets the weight G so that the pendulum P¹ has
the same period of oscillation as the pendulum P at the station to be called, and
presses down the key t. The pendulum P₁ starts swinging and the contact k leaves
the contact F just as the pendulum P' nears the perpendicular, the circuit is
interrupted and all the relays R at the several receiving stations close the circuits
of the local batteries B thus exciting the electromagnets E and vibrating the
armatures A. The pendulums P thus lose the support of the arm and fall slightly
towards the armature. As the pendulum P' oscillates it closes again the contact
at Fk when it reaches its lowest position. The armatures A are released and the
arms drawn by springs n strike the plates a thus giving an impulse to the

page_text: pendulums P. This impulse is repeated each time the contact at k F is remade and
is therefore synchronous with the period of oscillation of the pendulum P¹.
Amongst the pendulums P there will be some probably whose periods are faster
than that at which the pendulum P¹ is temporarily set, others will have slower
periods while only one has the same period. Consequently the impulses given to
the plates a will either be too slow or too fast for all the pendulums P except the
one at the station to be called, and at this station they will synchronize with the
period of the pendulum and consequently set the same swinging with amplitude of
oscillation sufficient to bring a pin 6 on the pendulum into engagement with a hook o
thus completing a local circuit including a battery and a signal bell. The bell will
continue to ring until an attendant releases the pendulum and returns it to its resting
position. The pin 6 might touch a spring or lever i (Fig. 2) instead of becoming
engaged in a hook c, the spring or lever causing a circuit to be closed which will
set the bell ringing, or any suitable arrangement may be made by which if any
pendulum P is set in oscillation of sufficient amplitude a local signal, audible or
visible will be brought into action.
In the modified construction of Fig. 2, the armatures A pivoted at o when
attracted pushed down a hammer H and presses its end under a detent f. When
the armature again rises its pin e strikes the arm g of the detent f and moves the
latter so that the hammer falls and has the same effect on the plate a as the arm v
in Fig. 1.
In continuous current lines without relays a similar arrangement may be used in
the receiving station as in Fig. 2 but the armature A is pivoted at a instead of at o,
the main line L leads to the electro magnet E and keeps the armature A attracted
until it is temporarily released.
In lines where the current is not continuous but acts only when contact is made,
B is the battery, under which term is included any suitable electric source, with
branch circuit, the contact being made and broken by the contacts Fk as described.
The sending of the current sets the relays in action..
In lines with such working currents and without relays the same arrangements
are employed except that the main current acts directly upon the electro magnet E.
If the contacts k and F are arranged as in Figs. 4 or 5 pendulums P' may be
used whose periods of oscillation are double that of the pendulum at the station to
be called.
Instead of a pendulum any balanced device having a relative period of oscillation
may be used, for instance a balance wheel as shown in Fig. 6, such a wheel will
have a pallet similar to the plate a on which the armature A or equivalent hammer
may act.
If the impulses synchronize with the period of oscillation of the balance
the amplitude of its swing is increased until the pallet touches the spring or
equivalent c.
In place of a pendulum in the calling station there may be used any suitable
clockwork to which may be fitted one of a series of disks or other devices adapted
to be revolved or moved by the said clockwork and so produce recurrent contacts
at the intervals of time at which the impulses are desired, that disk or device being
chosen by the signaller which in its movement will cause the contacts to synchronize
with the period of the pendulum or balance at the station to be called.
Having now particularly described and ascertained the nature of this said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1) In an electric circuit comprising calling stations and receiving stations for said
calls, apparatus comprising at the calling stations a pendulum with adjustable
period of oscillation and at the respective receiving stations pendulums each of a
different period of oscillation, adapted to receive impulsions electrically transmitted
by virtue of contacts made or broken by the calling pendulum, said impulses being
constant in value and independent of the power of the current whereby that receiving
pendulum whose period is approximately the same as that of the calling pendulum

page_text: will receive recurrent impulses synchronizing with its period and thus be set in oscillation
of sufficient amplitude to cause the entrance into continuous action of signalling
apparatus at the respective receiving station.
2) The variation of the method described in Claim 1 whereby the calling
pendulum may be of double the period to the pendulum at the respective receiving
station to be called.
3) The variation of the method described in Claim 1 whereby balancing devices
may be used in place of pendulums.
4) The variation in the method of transmitting impuises, as an additional feature
of the method described in Claim 1, consisting in the employment of a clock at the
calling station fitted with interchangeable disks or other devices for transmitting
impulses of the desired frequency.
5) In the receiving stations a method of operating the pendulum independent in
force from the power of the magnet E, whereby the said magnet through its
armature sets and releases a hammer H for the purpose set forth.
6) The arrangement by which when in a state of rest the pendulums Pare
maintained slightly out of the perpendicular, as an additional feature in the method
described in Claim 1 consisting in causing the armature V or the hammer H to touch
the side arm a of the said pendulum when at rest, for the purpose set forth.
Dated this 17th day of November 1892.
R. HADDAN,
Herbert Haddan & Co.,
18, Buckingham Street, Strand, London, Agent for Applicant.