Improvements in the Means for Telephonic Communication.
Year: 1891

page_text: Date of Application, 28th Mar., 1891
Complete Specification Left, 23rd Dec., 1891-Accepted, 23rd Jan., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Means for Telephonic Communication.
I, ETIENNE MASSIN of No. 94, Boulevard Raspail, Paris, France, Telegraph
Engineer, do hereby declare the nature of this invention to be as follows:-
With the usual arrangement of telephonic apparatus, the transmitter has a pre-
judicial effect on the receiving of speech, and the receiver has the same effect on
the transmission, in weakening the current on starting. This inconvenience is of
little importance in most cases on account of the small amount of energy required
of the apparatus, but if the line of transmission is a long one the sounds only arrive
in a weakened condition at the receiver, and it is necessary to carefully eliminate
all causes of weakening that do not result from the line wire itself. It would there-
fore be of advantage to cut out the receiver at the sending station, and the trans-
mitter at the receiving station, and my present invention consists in accomplishing
this object, whereby in addition to the above advantage, the further ones are
obtained that, firstly, the operator at the sending station of a long line does not have
his ears affected by the currents emitted by his transmitter and which pass through
his own receiver; and secondly, it is possible to increase the currents circulating in
the primary circuit without having to fear that the currents passing through the
microphone of the receiving station will cause crepitations in the receiver that
interfere with the hearing.
The arrangement applies as well to the microphone apparatus with induction
coils, as to those placed directly in the circuit. The invention may be carried out
in a variety of ways; thus according to one arrangement the two receiving instru-
ments and the secondary circuit of the induction coil are connected at one end to
the line wire, or to one of the line wires, the second wire or the earth contact being
connected to the fixed part of a contact key which in the position of rest closes the
circuit of the two receivers but which when pressed upon introduces the secondary
circuit of the induction coil into the line under exclusion of the receivers.
This key may, for example, be contained in the handle of a receiver and be
actuated by the thumb of the operator, consisting merely of a spring contact arm
that makes a different contact in each position. Instead of placing the transmitter
and receiver on a shunt from the line wire, they may be arranged in series on the
circuit, as in the ordinary way of mounting; in that case the one or the other
instrument is neutralised by short circuiting by means of the said key.
In a microphone with direct action, the microphone itself is introduced into or
cut out of the line, in place of the secondary circuit of the induction coil.
Dated this 28th day of March 1891.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Means for Telephonic Communication.
I, ETIENNE MASSIN of No. 94 Boulevard Raspail Paris, France, Telegraph
Engineer do hereby declare the nature of this invention and in what manner
he same is to be performed, to be particularly described and ascertained in and
by the following statement:-
With the usual arrangement of telephonic apparatus, the transmitter has a
prejudicial effect on the receiving of speech, and the receiver has the same effect on
he transmission, in weakening the current on starting. This inconvenience is of

page_text: little importance in most cases on account of the small amount of energy required of
the apparatus, but if the line of transmission is a long one, the sounds only arrive in
a weakened condition at the receiver, and it is necessary to carefully eliminate all
causes of weakening that do not result from the line wire itself. It would therefore
be of advantage to cut out the receiver at the sending station and the transmitter
at the receiving station, and my present invention consists in accomplishing this
object, whereby, in addition to the above advantage, the further ones are obtained
that, firstly, the operator at the sending station of a long line does not have his
cars affected by the currents emitted by his transmitter and which pass through his
own receiver, and secondly, it is possible to increase the currents circulating in the
primary circuit without having to fear that the currents passing through the
microphone of the receiving station will cause crepitations in the receiver that
interfere with the hearing.
The arrangement applies as well to the microphone apparatus with induction
coils, as to those placed directly in the circuit.
I also provide the apparatus with a commutator whereby the telephonic receiver
can be made use of in the same manner as an ordinary receiver. The advantage of
this commutator is that by means thereof my improved apparatus can be used as an
ordinary apparatus which can be employed by any one, so that the above described
device is only put in action when the transmission is defective.
On the accompanying drawing
Fig. 1 shews a sectional front elevation of my said improved apparatus,
Fig. 2 shews a vertical section at right angles to Fig. 1 and
Fig. 3 shows a cross section on line M N Fig. 1.
The arrangement comprises a key e, a push button p, and the contacts a and b,
these parts being fixed to a cover Å which closes the box or casing B forming the
handle of the telephone. As shewn more clearly in the diagram at Fig. 4, the
key when at rest, closes the line circuit for the two receivers R; when on
the other hand the key is pressed upon by the button p, the secondary circuit X of
the induction coil is connected with the line circuit to the exclusion of the
receiver.
The commutator, placed by preference at the end of the handle, is arranged as
follows. A cross piece d is fixed upon the stem e of an external button, so that
by turning the latter in one direction or the other the cross piece can be made to
assume two opposite positions at right angles to each other. The cross piece is
acted upon by a spring g, and constitutes the commutator, making or breaking
contact between two contact springs and k.
The contact spring his connected by a wire to the contact band a receiver, the
other, is connected to the contact a so that when the commutator is turned into
the position shewn at Fig. 1 so as to make contact with h and k, it temporarily
connects the two contacts a and of the push p, thus placing the receivers simply
on a shunt on the transmitter. If the button of the commutator be turned
through 90°, the connection between and is broken, and the receivers operate
as explained above. The motion of the commutator is limited by stops 1.
The arrangement of the apparatus will be readily understood on reference to the
diagrams Figs. 4 and 5, of which Fig. 5 shews the apparatus arranged for ordinary
working and Fig. 4 the arrangement for working according to my invention.
For arranging the amplifying receiver on a microphonic transmitter provided
with a hook commutator placed between the line and the induction coil, it is
necessary:
1, toremove the two receivers ;
2, to take one of these and connect it on the one hand at m with the screw that
fixes one of the ends of the induction coil to the hook commutator, and on the other
hand at n with one of the contact screws serving to connect the two receivers in
the ordinary mode of working;
3, to connect the yellow wire (1) of the amplifier to the second one o of these
contact screws;

page_text: +, to connect the green wire (3) to the contact screw p, to which, in the ordinary
mounting, are connected one of the receivers and the second extremity of the
induction coil;
5, to connect the red wire (2) to the fourth contact screw q to which are
ordinarily connected the line circuit L' and one of the receivers R."
It is necessary, in order to obtain the maximum effect, to make use of a battery
of very small internal resistance and as strong as possible, without however unduly
exaggerating the sounds at the receiver.
It is indispensible to have a battery commutator arranged in any known manner
so as to enable a weaker current to be employed when the said connections are not
established by pressing the button p.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. The herein described arrangement of apparatus for preventing in any micro-
phonic apparatus, the simultaneous connection with the telephonic circuit, on the
one hand, of the receivers, and on the other hand of either the whole or a part
of the transmitting devices, substantially as set forth.
2. The use of a commutator arranged substantially as herein described whereby
the apparatus referred to in the preceding claim can be temporarily thrown out
of action so as to convert the receiver with push button into an ordinary
receiver, and leaving the transmitters and the receivers in the circuit, substantially
as set forth.
Dated this 23rd day of December 1891.
ABEL & IMRAY,
Agents for the Applicant.