Improvements in Telephonic Apparatus.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Telephonic Apparatus.
HENRY CAPEL LOFFT HOLDEN Major, Royal Artillery Royal Arsenal
Woolwich do hereby declare the nature of this invention to be as follows:-
My invention consists in improvements in the apparatus used for telephonic
communication and in the methods of electrical connection with the line wire or
wires, of the apparatus for calling attention and those for speaking, whereby the
change from the calling apparatus to the speaking apparatus is made with more
certainty than at present; and my methods of connection and instruments can be
so arranged and adjusted that under no circumstances, excepting of course when
the line wire or wires are actually broken or disconnected, can the conversation be
interrupted or the call signal cease to be given through the failure of the
switches that control the connections, or through a mistake on the part of the
operator.
In order to effect this purpose I arrange the connections of my apparatus in
various ways.
By one method, I connect my calling apparatus whether bell, relay, or
galvanometer or other analogous instrument, in series with my telephone receiver
and transmitting apparatus so that any currents entering the former from the line
would pass through the latter to the earth or by means of the return wire to the
distant station.
I arrange a switch, actuated by means of the weight of the telephone or by
other means so that when conversation is not required the terminals of the
telephonic portion of the apparatus are connected together and thus short circuited,
the whole of the received current being thus effective in actuating the call signal,
whereas when the telephone is in use the terminals of the calling apparatus are
short circuited and the whole current is effective for speaking; in the event
however of the switch entirely failing to act, the only result is that the ringing
current and also the speaking current are reduced but not to such an extent as to
seriously affect the action of either portion of the apparatus.
By another method, I connect the calling apparatus in parallel with the
telephonic apparatus so that the currents divide between them in inverse pro-
portions to their resistances, and in this case no switch is required.
By still another method I connect one pole of the line wire to one terminal of
the calling apparatus and also to one terminal of the speaking apparatus; the
other terminal of the calling apparatus being connected to earth or to the return
wire, and the other terminal of the speaking apparatus being connected to one pole
of a suitably proportioned condenser the other pole of this condenser being
connected to earth or to the return wire.
A switch is so arranged that when the apparatus is in use for speaking the
condenser is short circuited; this can be effected by means of a switch actuated
by the weight of the telephone or worked by hand or other means as considered
lesirable.
Dated this 22nd day of June 1895
H. C. L. HOLDEN,
Major, R.A.

page_text: I, HENRY CAPEL LOFFT HOLDEN Major in H.M. Royal Artillery Royal
Arsenal Woolwich S E. 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 :-
My invention relates to improvements in the apparatus used for telephonic
communication and in the methods of electrical connection with the line wire or
wires of the instruments used for calling attention and these employed for speaking
purposes.
These connections are so arranged by my methods that the change from the
calling apparatus to the speaking instruments is made with more certainty than is
at present the case, and are so arranged and adjusted that under no circumstances
excepting when the line wire is actually broken or otherwise disconnected from
the apparatus, can the call signals fail to be given or the conversation be interrupted
through the failure of the switches that control the connections or through a
mistake on the part of the operator.
In order to effect this purpose I arrange the connections of my apparatus in one
of the following ways, which I will now proceed to explain referring to the
accompanying diagrams with a view to rendering my invention clearer.
In these diagrams similar letters denote similar and corresponding portions of
the apparatus in each case.
By my first method shown in the diagram Fig. 1. 1 connect my apparatus for
calling attention B, whether it be acoustic such as a bell, visual such as a
galvanometer, or relay for operating a local circuit or other analogous instrument
as ordinarily in use for the same purpose, in series with the telephonic transmitter
and receiver T to the line wire L'and to the return wire or earth R.
1 furthermore arrange a switch E, so that either the calling apparatus B or
the telephone apparatus T, may be shunted by making contact at K and Q
respectively with a wire having more or less resistance as circumstances may
require.
This switch E may be worked automatically in the usual manner by the
employment of the weight of the telephone receiver to press it against the
contact Q, a spring S or equivalent means being employed to press it against
the contact K when the telephone receiver is removed.
By this means when the telephone apparatus is not in use it would be shunted
and when the telephone apparatus is in use, the calling apparatus would be
shunted.
In the event however of the switch not making proper contact in either of its
two positions, the result would merely be to reduce the effects in both the calling
and speaking apparatus, in proportion to the increased resistance.
By a second method shown in Fig. 2, I connect both my calling apparatus B
and speaking apparatus T in parallel to the line wire L and to the return wire or
earth R, the resistance and self induction of the calling apparatus being high
compared to, and suitably proportioned to that of the calling apparatus so that the
efficiency of the telephone apparatus is not impaired.
By a third method shown in Fig. 3. I connect one terminal of the calling
apparatus B to the line wire L and its other terminal to the return wire or
earth R, and one terminal of the speaking apparatus to the line wire L and the
other terminal to one pole of a suitably proportioned condenser C, the other pole
of this condenser being connected to the return wire or earth R. A switch E
automatic or otherwise is so arranged that when speaking the condenser can be
short circuited by connecting its poles together.

page_text: 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;
The improved method or methods of electrical connections in apparatus used for
telephonic purposes substantially as described and for the purposes hereinbefore
set forth.
Dated this Twenty-fourth day of March 1896
H. C. L. HOLDEN,
Major, R.A.