Improvements in Telephonic Apparatus.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Telephonic Apparatus.
I, ALFRED GRAHAM, of 32 De Crespigny Park, Denmark Hill, in the County
of London, Electrician, do hereby declare the nature of this invention to be as
follows:-
In telephonic apparatus according to this invention, a rotary transmitter, of the
Hunnings type, and a fixed receiver, preferably of my well known loud speaking
type, are arranged adjacent to each other, and in front of them there is provided
a movable plate or shutter that is connected with the transmitter, the arrangement
being such that normally the plate or shutter closes the front ends of both
instruments so as to protect the same, and that in order to use the apparatus, the
plate or shutter must be moved into a position to uncover both instruments so that
motion will be imparted to the transmitter and the powdered carbon therein shaken
up each time the apparatus is used, whereby the same is at all times maintained in
good working order. The movement of the plate or shutter may also be utilized to
operate a switch controlling the circuits of the instruments.
In one arrangement of telephonic apparatus according to this invention, the
receiver and transmitter are arranged one above the other in a case in the front
wall of which the flaring end of the receiver cone and the front end of the
transmitter, which is preferably protected by wire gauze, terminate. The movable
plate or shutter is in the form approximately of two connected dises provided with
a handle and fixed at the front of the case on a spindle that is connected by gearing
to the transmitter case and is provided with a cam or equivalent for controlling the
contacts of a switch. The receiver is made substantially in the manner described
in the Specification of my Patent No. 12516 of 1893, but the permanent magnet is
of semi-annular form with its free ends bent radially inward and provided with
polar extensions that terminate in proximity to the receiver diaphragm and are
provided with wire coils of low resistance. The transmitter is made substantially
in the manner described in my said former specification but is without the flaring
mouth piece and without the handle and circuit closing key, and the quantity of
powdered carbon enclosed in the space between the diaphragm and the carbon
block, which is provided with projections, is insufficient to fill such space so that
when the transmitter is rotated the powdered carbon will be agitated. The
transmitter case is mounted at one end to rotate in the front wall of the apparatus
and at the other end to rotate upon a pin which may conveniently be supported
by an extension of the bearing for the inner end of the spindle. This bearing
may be carried by the receiver which is fixed to the enclosing case. A calling
key for closing a bell circuit may be provided at the front of the apparatus.
The switch and the connections controlled thereby may be variously constructed
and arranged. A convenient arrangement is as follows:-The switch comprises
two spring contacts I will call for distinction a and b the positions of which are
controlled by a cam on the shutter spindle, and three fixed insulated contacts I will
call c d e. There are also provided six terminals which I will number respectively
1 to 6. The spring contact a is permanently connected at one end with terminal 5
and at its other end normally bears against the contact d which is connected to
terminal 4. The contact b is permanently connected at one end by a fixed brush

page_text: and a plate on the back of the transmitter case to one terminal of the transmitter,
the other terminal of which is suitably connected, as through the metal front plate
of the case, to terminal 1. The free end of contact b is normally away from but
in proximity to contact e which is connected to terminal 6. Contact c, which is
arranged on the opposite side of contact a to that at which contact d is arranged,
is connected to one end of the coils of the receiver, the other end of these coils
being connected to terminal 2 which is permanently connected to terminal 3 and
both of which are connected to each or a return conductor. When a calling
key is provided it is arranged to press a spring contact, that is suitably connected
as through the metal front plate of the case of the apparatus, to the terminal 1,
against a fixed contact that is connected, it may be through contact e, with
terminal 6. A battery is placed in circuit between terminals 1 and 2, and a call
bell between terminals 3 and 4, terminals 5 and 6 being connected to leads that are
connected or adapted to be connected to the terminals 6 and 5 respectively of a
similar apparatus arranged at another place with which it is desired to communicate
telephonically. Assuming two such apparatus to be thus connected up and that
the shutter of each is closed, then the receiver and transmitter of cach apparatus
will be out of circuit, but the call bell of either apparatus can be rung up from the
call key of the other apparatus. If then the shutters of both instruments be
opened the spring contacts a and 6 of each apparatns will be caused to bear upon
the adjacent contacts c and e, with the result that the transmitter of each apparatus
will be connected with the receiver of the other apparatus the circuit including
one transmitter and receiver being independent of that in which the other trans-
initter and receiver are included, as in the arrangements described in ny said
former specification.
As will be obvious my apparatus may be variously modified in detail. Thus
instead of providing a battery in connection with each apparatus, a single battery
may be combined with several apparatus which may be connected up as. described
in my said former specification.
By my invention I am able to provide a compact and efficient loud talking
apparatus not liable to be easily damaged and which is suitable for use on
war-ships, in works, mines and other places where such an apparatus is
desirable. For war-ships I prefer to make the case of the apparatus wholly of
metal.
Dated this 25th day of March 1806
I, ALFRED GRAHAM, of 32 De Crespigny Park, Denmark Hill, in the County
of London, 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 :-
In telephonic apparatus according to this invention, a rotary transmitter of the
Hunnings type, and a fixed receiver, preferably of my well known loud speaking
type, 'are arranged adjacent to each other, and in front of them there is provided
a movable plate or shutter that is connected 'with the transmitter, 'the arrangement
being such that normally the plate or shutter closes the front ends of 'both
instruments so as to protect the saine, and 'that in order to use the apparatus, 'the

page_text: plate or shutter must be moved into a position to uncover both instruments so that
motion will be imparted to the transmitter and the powdered carbon therein shaken
up each time the apparatus is used, whereby the same is at all times maintained in
good working order. The movement of the plate or shutter may also be utilized
to operate a switch controlling the circuits of the instruments.
In the accompanying drawings
Fig. 1 is a front elevation; Fig. 2 a cross section, partly in elevation, and Fig. 3
a rear elevation with part removed, showing one arrangement of telephonic
apparatus according to this invention.
Fig. 4 is a horizontal section on the line y y of Fig. 3;
Fig. 5 shows in elevation, a set of terininals; and
Figs. 6 and 7 are diagrams showing the electrical connections of two sets of
apparatus.
Fig. 8 is a detail view of the bell push.
1 is the receiver and 2 the transmitter arranged one above the other in a case 3
at the perforated front wall of which the flaring end of the receiver cune 1 and the
front end of the transmitter, which is preferably protected by wire gauze 2ª (Fig. 1),
terminate as shown. 4 is the movable plate or shutter in the form approximately
of two connected dises provided with handles or knobs 4, or there may be only
one, by which it can be partly rotated. It is fixed at the front of the case un a
spindle 5 that is connected by toothed wheels 6 and 6* to the case of the
transmitter 2 and is provided with a cam 7 (or equivalent) for controlling the
contacts of a switch as hereinafter described. The spindle is journalled at one end
in the front wall of the case 3 and at the other end in a bearing 8 carried by the
receiver which is fixed to the said front wall of the case. The spindle is
provided with a projecting part 5 arranged to work between lugs 3 which are
formed on the inner side of the front wall of the case 3 and serve to limit the
extent of rotation of the plate or shutter 4 which, after being moved to either side
and released is automatically returned to its vertical and closed position and held
in this position by a pair of coiled springs 9 connected to the toothed wheel 6 and
to fixed parts of the apparatus.
The receiver 1 is of the magneto-electric type and is made substantially in the
manner described in the Specification of my Patent No. 12516 of 1893, but the
permanent magnet 10 is of semi-annular form with its free ends 10 bent radially
inward and provided with polar extensions 10 that terminate in proximity to the
receiver diaphragm 11 and are provided with wire coils 12 of low resistance. The
transmitter 2 is of the Hunnings type and comprises a case in which powdered
carbon is enclosed in a space between a carbon diaphragm and a carbon block, the
quantity of carbon used being insufficient to fill the said space so that when the
transmitter is rotated the powdered carbon will be agitated. The transmitter case
is mounted at one end to rotate in the front wall of the case 3, as shown, and at the
other end to rotute upon a pin 13 which is carried by a bridge piece 14 fixed to the
front wall of the case 3. The toothed wheel 6 is insulated from the transmitter
by an insulating block 6. A calling key 15 (Figs. 1 and 8) for closing a bell
eireuit may be provided at the front of the apparatus.
The switch and the connections controlled thereby may be variously constructed
and arranged. A convenient arrangement is as follows:-The switch comprises
(a) two insulated spring contacts 16 and 17 that are fixed to an insulating block 18
and the positions of which are controlled by the cam 7 on the shutter spindle 5,
and (b) three fixed insulated contacts 19, 20 and 21 carried by an insulating
block 22. There are also provided six terminals which I will number respectively
1 to 6. These terminals are mounted upon a base 3 shown separately in Fig. 5
and the position of which in the apparatus may conveniently be that indicated by
the dotted lines in Figs. 2 and 3. The spring contact 16 is permanently connected
at its fixed end with terminal 5* and at its other end normally bears against the
contact 20 which is connected to terminal 4. The contact 17 is permanently
conuected at its fixed end by a fixed brush 23 (Fig. 3) and an insulated metal

page_text: plate 24 on the back of the transmitter case to one terminal of the transmitter, the
other terminal of which is suitably connected, as through the metal front plate of
the case, to terminal 1. The free end of contact 17 is normally away from but in
proximity to contact 21 which is connected to terminal 6. Contact 19, which is
arranged on the opposite side of contact 16 to that at which contact 21 is arranged,
is connected to one end of the coils 12 of the receiver 1, the other end of these coils
being connected to terminal 2 which is permanently connected to terminal 3* and
both of which are connected to earth E, or a return conductor. When a calling
key 15 is provided, it is arranged to press a spring contact 25 (Figs. 1 and 8)
which is suitably connected, as through the metal front plate of the case of the
apparatus, to the terminal 1, against a fixed contact 26 which is connected, it may
be through contact 21 with terminal 6. A battery 27 is placed in circuit between
terminals 1 and 2, and a call bell 29 between terminals 3 and 4, terminals 5*
and 6 being connected to leads 50 and 31 that are connected, or adapted to be
connected, to the terminals 6 and 5 respectively of a similar apparatus arranged
at another place with which it is desired to communicate telephonically.
Assuming two such apparatus to be thus connected up, as shown diagram-
matically in Fig. 6, and that the shutter 4 of each is closed, then the receiver and
transmitter of each apparatus will be out of circuit, but the call bell of either
apparatus can be rung up from the call key 15 of the other apparatus. The path
of the ringing up current from the left hand apparatus (Fig. 6) will be from one
pole of the left hand battery 27 through the metal case 3 of the apparatus,
contacts 25, 26, 21, terminal 6 and lead 31 to the terminal 5 of the right hand
apparatus, thence through the contacts 16, 20 and terminal 4 to the right hand
hell 29 and thence by the connected terminals 3* 2 to earth or return conductor
and terminal 2 of the left hand apparatus to the other pole of the left hand
battery. The path of the current from the right hand apparatus will be readily
followed from the diagram Fig. 6. If, after ringing up, the shutters 4 of both
instruments be opened, the spring contacts 16 and 17 of each apparatus will be
caused by the cams 7 to move from the normal positions shown in Fig. 6 to that
shown in Fig. 7 so as to then bear upon the adjacent contacts 19 and 21 respectively
with the result that the transmitter of each apparatus will be connected with the
receiver of the other apparatus, the circuit including one transmitter and receiver
being as will be seen from Fig. 7 independent of that in which the other
transmitter and receiver are included, as in the arrangements described in iny said
former specification.
As will be obvious my apparatus can be variously modified in detail. Thus
instead of providing a battery in connection with each apparatus, a single battery
may be combined with several apparatus.
By my invention I am able to provide a compact and efficient loud talking
apparatus not liable to be easily damaged and which is suitable for use on war
ships, in works, mines and other places where such an apparatus is desirable. For
war-ships I prefer to make the case of the apparatus wholly of metal.
Having now particularly described and ascertained the nature of the said inven
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Telephonic apparatus wherein a rotary transmitter of the Hunnings type, and
a fixed receiver are arranged adjacent to each other and there is provided in front
of them a movable plate or shutter that is connected with the transmitter, the
arrangement being such that normally the plate or shutter closes the front ends of
both instruments and that in order to use the apparatus, the plate or shutter must
be moved into a position to uncover both instruments so that motion will be
imparted to the transmitter and the powdered carbon therein shaken up each time
the apparatus is used, substantially as herein described for the purpose specified.
2. In telephonic apparatus, the combination with a rotary transmitter of the
Hunnings type and a switch, of a rotary plate or shutter arranged at the front end

page_text: of the transmitter and carried by a spindle that is connected by toothed gearing
with the rotary transmitter and is provided with a cam arranged to operate the
said switch, the arrangement being such that normally the rotary plate or shutter
covers the transmitter and the switch is in a position in which the transmitter and
receiver are out of circuit but will allow of the closing of a call circuit and that in
order to allow of telephonic messages being sent the rotary plate or shutter must
be partly rotated whereby the transmitter will be rotated and the switch operated
to put the transmitter and receiver in circuit, substantially as described.
3. Telephonic apparatus of the kind specified in the preceding claims wherein a
magneto electric receiver, Hunnings transmitter, enclosing case, and movable plate
or shutter are constructed and arranged substantially as hereinbefore described
with reference to Figs. 1 to 4 inclusive of the drawings annexed.
4. My improved telephonic apparatus with switch and electrical connections
constructed, arranged and operating substantially as hereinbefore described with
reference respectively to and shown in the drawings annexed.
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.