Method of Indicating at a Telephone Station whether the Telephone Lines are Engaged or not.
Year: 1896

page_text: Date of Application, 5th June, 1896-Accepted, 8th Aug., 1896
COMPLETE SPECIFICATION.
Method of Indicating at a Telephone Station whether the Telephone
Lines are Engaged or not.
I, EMIL NAGLO, of Koepenicker-Landstrasse, Berlin, in the Empire of Germany,
Electrical 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 has for its object a method for the simplification of the working
of telephone stations in which each line can be engaged at several points, so that
it is necessary to have means whereby the operator, before connecting a line can
ascertain whether the said line is possibly already engaged.
This object is attained according to the present invention in such manner, that.
on connecting a line, that is, in putting in a plug in one of the jacks of said
line-a subsidiary circuit is closed or opened in which is contained a small glow
lamp, which accordingly indicates the fact of the telephone line being engaged
in the first case by glowing, and in the second case by being extinguished; on the-
other hand it will show the disconnection by the reverse action.
On the accompanying drawing Figure 1 shews a diagram of two subscriber's
lines T and T running through three multiple switch boards I II III of a
station. To the right hand is a glow-lamp board G T, consisting of a framing
formed of metal bars effectually insulated from earth. A number of glow-
lamps g g corresponding to the number of subscribers are fixed on the bars in
such manner that the one pole thereof is in conducting connection with the bar
while the other pole is connected to an insulated contact d of the corresponding
indicator and with the spring f₁ of the jack of the same number. The glow
lamps can be so arranged that they illuminate a transparent plate from behind,
which carries on the back surface the subscribers number; this is then visible so.
long as the lamp glows, but disappears as soon as it is extinguished. The
battery B is connected with the lever H of the switch U; if H is sitnated ou
contact 1, B is out of circuit; if H is on 2 on the other hand, B is directly
connected to the glow lamp; between the two the night call bell W is introduced,.
if H is turned on to contact 3.
Generally, H is on contact 2; as will be readily seen in Figure 1, the lamp g¹
will light up as soon as the shutter K¹ falls at the call of a subscriber, as the
spring bears against the contact d thereby closing the circuit from the lamp gl
to the battery B. If the operator then introduces the plugs shewn at Figure 2
of the connecting cord into the jack k¹ of the switch-board I the ring r of the
plug will effect the closing of a second circuit through the springs f¹ and f² to
the battery from the lamps g'; consequently when the operator raises the
shutter K again the lamp will continue to glow as long as the plug remains in
the jack k. If a subscriber, for instance T, is called, his glow lamp g will.
light up at the moment when a plug is inserted in one of his jacks, and
it will continue to glow until the plug is withdrawn, i.e., as long as the line is
occupied.
The glow lamp board is so arranged that it can be readily seen from all the
switchboards, so that each operator can see at a moment from the lamp board,
when a connection is desired, whether the required line is engaged or not.
large stations several of such lamp boards may be provided.
In
It will be evident that the converse arrangement could be adopted, whereby on
the falling of the shutter and on inserting a plug, the lamp circuit is interrupted,

page_text: so that the lighting up of the lamp then indicates that the line is free, and the
extinguishing thereof, that the line is engaged.
In order not to lead the somewhat strong current for the lamps through the
switchboards, whereby the telephonic circuits and the switchboard system might
be prejudicially affected, there may be introduced into the respective circuits
relays which open and close the lamp circuits situated entirely outside the
switchboards.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Method for indicating whether the subscribers lines led into a telephonic
station are engaged or not, wherein on calling, or the falling of the call relay or
indicator shutter, and also on plugging a jack, the circuit of a glow lamp carrying
the number of the circuit is closed or opened, either directly or through the
medium of a relay, so that the appearance of the number of the circuit will
indicate in the one case that the line is engaged, or in the other case that the line
is free, substantially as described.
2. In the method referred to in the first claim, the combining of the control
glow lamps to form a special glow lamp board which indicates simultaneously for
several switchboards whether the lines of the station are free or engaged,
substantially as described.
Dated this 5th day of June 1896.
ABEL & IMRAY,
Agents for the Applicant.