An Improved Telephone Combination.
Year: 1892

page_text: Date of Application, 1st June, 1892
Complete Specification Left, 1st Dec., 1892-Accepted, 7th Jan., 1893
PROVISIONAL SPECIFICATION.
An Improved Telephone Combination.
I, Sir CHARLES STEWART FORBES, Baronet, 11 Glendower Place, London,
S.W. East India Agent, do hereby declare the nature of this invention to be as
follows:-
My invention consists in an improved form of telephone combination for
domestic, or other use. For house or office use I prefer to so construct my
improvements as to enable the ordinary electric bell push and the wires connected
thereto to be utilized for speaking as well as ringing purposes, but I do not confine
myself wholly to such adaptation as the particular construction hereinafter
described admits of a wider application. A case of wood, ebonite, china or any
suitable substance is constructed and fitted by screwing or otherwise to the seating
block of the ordinary bell push or in any other manner convenient for my purpose.
Upon a piece of soft wood covered preferably with violin or other varnish, or
upon a flexible metallic or other diaphragm, I mount a microphone of any type
suited to my purpose. I employ two tympans held apart by suitable means
between which are placed the inducing bobbins and cores as well as the circular or
other shaped magnet supporting them. A tube is inserted in any convenient
position between the tympans and is flexibly connected with a mouthpiece or ear
trumpet or trumpets (as the case may be) which when not in use for speaking or
receiving purposes depresses a switch lever which cuts out the telephone and puts
the ringing key or equivalent into connection with the bell and the indicator
circuit. Upon lifting the elastic tube and mouthpiece, the indicator falls and the
bell at the other end of the line rings. The indicator is preferably so constructed
as that in falling it removes or cuts out the resistance of its own coils from the
line. Upon the attendant raising the speaking trumpet to answer, the bell is cut
out and the telephone put into circuit. An advantageous feature of my invention
consists in the fact that the line is always controlled by the principal, who is able
to use the push or ringing key in the ordinary way independently of the telephone,
when the personal attendance of the servant, clerk, or messenger is required, but
such servant or attendant cannot by raising the receiving tube either ring or listen
to conversation passing unknown to the principal.
The instrument described may be so constructed as to permit several stations or
centres to be called from one central office.
Dated June 1st. 1892
FRANCIS M. ROGERS,
Agent
COMPLETE SPECIFICATION.
An Improved Telephone Combination.
I Sir CHARLES STEWART FORBES, Baronet, 28 Queen's Gate Terrace,
London, S.W. East India Agent, 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 consists in an improved form of telephone combination for domestic
or other use and is carried out as follows. A case of wood, ebonite, china or any
suitable substance is constructed, and fitted by screwing or otherwise to a suitable
seating block let into the wall or in any other manner convenient for my purpose.
Upon
a piece of soft wood covered preferably with violin or other varnish, or upon
a flexible inetallic or other diaphragm, I mount a microphone of any type suited
Prics &dl

page_text: to my purpose, I employ two tympans held apart by suitable means, between which
are placed the inducing bobbins and cores as well as the circular or other
shaped magnets supporting them. A tube is inserted in any convenient position
between the tympans and is flexibly connected with a mouthpiece or ear trumpet or
trumpets (as the case may be) which when not in use for speaking or receiving
purposes depresses a switch lever which cuts out the telephone and puts the ringing
key or equivalent into connection with the bell and the indicator circuit. Upon
lifting the elastic tube and mouthpiece the indicator falls and the bell at the other
end of the line rings. The indicator is preferably so constructed as that in falling
it removes or cuts out the resistance of its own coils from the line. Upon the
attendant raising the trumpet mouthpiece to answer, the bell is cut out and the
telephone put into circuit. An advantageous feature of my invention consists in
the fact that the line is always controlled by the principal who is able to use the
push or ringing key in the ordinary way, independently of the telephone when the
personal attendance of the servant, clerk, or messenger is required, but such
servant or attendant cannot by raising the receiving tube either ring, or listen to
conversation passing unknown to the principal.
The instrument described may be so constructed as to permit several stations or
centres to be called from one central office.
The construction and operation of my invention will be understood by reference
to the drawing, in which
Fig. 1. is a sectional view on line A. B., Fig. 2.
Fig. 2. is a front elevation, the microphone, wood and ferrotype tympans being
removed, but shewing the heads of the cramp pins.
Fig. 3. is a back view of microphone and wood tympan.
Fig. 4. is a back view of the instrument used at the servants' end of the line.
Fig. 5. is a sectional plan on line C. D., shewing polar extensions and inducing
bobbins.
Fig. 6. shews an alternative form of permanent magnet.
Fig. 7. is a section shewing same mounted up.
Fig. 8. a microphone mounted upon metallic tympan.
Fig. 9. a side sectional view of same.
The
1, is the case, which may be formed of wood, ebonite, stone or other ware.
mouthpiece 1 as well as the seating block 1b, are preferably united to the central
part 1, by screwing as shewn. The magnet consists of two or more horse-shoe
shaped solid steel bars 2, hardened and highly magnetized, but if desired they may
be formed of several bars or lamina riveted together, and separated by ebonite or
equivalent insulating packing 3. Soft iron polar extensions 5, secured to the end
of the magnet bars by screws 4, carry bobbins 6, filled with insulated wire 7,
united in series or parallel, the ends of these wires being connected on one side to
the copper strip 8, through the microphone 9, mounted on wood tympan 9ª, copper
strip 8 and brass cramp pin 10, and on the other to cramp pin 10°. These cramp
pins pass through insulated tubes 11, in the magnets, and vulcanized fibre, or other
insulating packing rings 12, one end being screwed into a split brass segment 14.
The packing rings 12, when screwed up by the brass cramp pins maintain the two
ferrotype tympans 13, in adjustment with the polar extensions 5. The split
segments 14, are brought into close electrical contact with the split brass
segments 15, attached by screws to the seating block 1, and with the copper
strips 8, 8ª and heads of the cramp pins 10, 10" which may be tinned or platinized
to ensure good electrical contact when the mouthpiece 1ª, is screwed up. Binding
screws 15, connect the segments 15, with the switch lever 16, and line wires 28,
which pass through holes in the loose wooden backing 17, and the seating block 1
more perfect contact between the segmental rings 14, 15, spring
contacts 18, (see dotted lines, Fig. 4) are fastened by screwing or riveting to the
ring segments 15. A metal ferrule 19, is screwed into a plate 20, fastened by
screws to the central part of the case, to this ferrule is fastened a flexible tube 21
fitted with an ear trumpet 22, which collects the sound waves from between the
To ensure

page_text: two tympans 13. When the telephone is not in use this ear trumpet 22, rests in
the fork 23, of switch lever 16, and causes its bend to rest against the idle or
inactive stop 24. Upon lifting the ear trumpet 22, out of the fork 23, the spring 25,
forces the bend of lever 16, against contact 26, thereby putting the telephone and
microphone into the circuit of the battery 27. Wires 28, connect the instrument
just described with that shewn in Fig. 4, at the servants or clerks end of the line.
This instrument differs only from that just described in having a bifurcated
ferrule 191 and two tubes 21, each having an ear trumpet 22, one of which rests in
a rigid fork 231, the other resting in fork 23, of switch lever 16, which when in the.
position shewn puts the line wire on to the bell contact 241, which in this instrument
replaces the idle contact 24. An ordinary electric bell 29, is inserted between this
contact and the battery and connected thereto by a separate wire.
The operation of my invention is as follows:-
When
When the telephone described under Figs. 1, 2, 5, is not in use, the bent end of
lever 16 rests against the inactive stop 24, and all connection with the other end of
the line is severed; when it is desired to speak, the tube 21, and ear trumpet 22, is
lifted out of the fork 23, of lever 16, the spring 25, now forces the bent arm of
lever 16, against the contact 26, and since the switch lever in the instrument
shewn in Fig. 4, at the kitchen or clerks end of the line is resting against the bell
contact 24', the current from the battery flows through the microphone 9, the coils
of the magnets 2, and those of the bell 29, causing it to ring. The attendant now
lifts both ear tubes out of the forks 23, 231, and the spring 25, re-acting, forces the
bent end of lever 16, against contact 26, thereby putting the microphone and
telephone into the battery circuit; conversation can now be carried on.
several instruments are connected with that shewn in Fig. 4, I employ an indicator
in each circuit as at 30. Any of the well known forms having low resistance may
be used, but I prefer to use one which short circuits its coils on the disc falling
in the manner well understood. It will be observed that no separate bell push is
required in the particular arrangement I have just described, and that the
attendant cannot listen to conversation in the callers room, since when not in use
the circuit with that instrument is broken. If it is desired, an ordinary independent
push may be bridged between the switch lever 16, and the line contact 26, and
mounted either upon the cylindrical part of telephone or at a distance from it.
In some cases I find it desirable to mount a microphone upon a metallic
diaphragm. This I accomplish as follows-A piece of carbon A, (see Figs. 8, 9,)
is coated with electro deposited copper upon its under side and then sweated with
solder to the metallic tympan or diaphragm 9. Two carbon blocks A1, A2, are
sweated in a similar way upon a thin piece of copper b, which is pinned upon a
similar segment of ebonite C, cemented to the tympan 9. A paper or rubber
segment or segments e, is cemented round the edge of the tympan so as to produce
a level surface, and a contact piece c¹, which may form part of the tympan, is bent
over as shewn, gripping the paper, this contact piece as well as the copper strip b,
is usually tipped with solder or other unoxidizable substance, so as to ensure
metallic contact with cramp screw 10, and the contact screw 7, (see Figs. 1, 7,) to
which the wire from the magnet coil is connected. Upon screwing up the mouth-
piece 1ª, perfect electrical connection is made thereby. In case it is required to
replace any part of the telephone it is only necessary to unscrew tube 19 or 19¹ as
the case may be and the mouthpiece 1ª. The entire speaking mechanism can then
be withdrawn without disturbing any wire connections, and on the other hand the
ingoing and outgoing wires can be detached or secured by unscrewing the central
part of the instrument 1, without disturbing the seating block 1b, thereby saving
much time and labour.
It is obvious that the ear tubes may be used for speaking as well as receiving
direct, without the intervention of the microphone if desired.
When several stations are called from a central office, as for instance when the
principal wishes to communicate with the manager or clerk in charge of a
department, I prefer to employ in connection with the instruments I have described

page_text: a switch of rotary or other form which is placed in the principal's office, the various
wires connecting the telephones placed in the clerks' offices or departments which
are fitted with ringing contacts and bells being connected thereto. The principal
can by rotating the switch lever or by similar well known means place himself in
communication with any desired office or room, and upon his raising the ear tube
in the manner described a current will flow from the battery along the selected line
and cause the bell to ring, the make and break action of the bell spring creates a
buzzing sound upon the tympans of the telephone in the principal's room, and
advises him that the bell is ringing at the far end of the line. Upon the manager
or clerk raising the ear trumpets the bell is cut out and the telephone placed in the
battery circuit and conversation can be carried on. Since the switch lever in the
principal's room has only a line contact and when not in use the bent end of lever
rests against an idle stop and therefore the circuit is broken, the respective lines
are entirely under the control of the principal, and cannot be used without his
consent.
I do not confine myself to the particular shape of the magnets described and
shewn in Figs. 1, 2, 5, as these may be varied to suit the class of instrument
required, for instance; the horse-shoe magnets shewn in the figures specified above
may be replaced by plain or laminated circular or other magnet or magnets similar
to those shewn in Figs. 6, 7, which carry only one bobbin on each pole. My
object is as far as possible to cheapen the construction of instruments suitable for
domestic use, and to enable defective parts to be replaced when necessary by
unskilled labour, this I accomplish by avoiding soldered joints and loose wire
connections, and at the same time I secure firm and permanent electrical contact
between the inter-acting parts.
To take out the microphone and telephone it is only necessary to unscrew the
mouthpiece 1, and the tube 19 or 19¹ which it will be seen maintains the telephone
, in position and prevents all lateral movement in screwing home the mouthpiece.
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. In a telephone combination the use and employment of the solid or laminated
horse-shoe or other shaped permanent magnets carrying soft iron polar extensions
and bobbins filled with insulated wire connected up as described. The double
tympans 13, enclosing said magnets, both being secured in position and the electrical
connections with the microphone established by means of the insulated cramp
pins 10, 10, passing through packing rings 12, and screwed into the split ring 14,
which forms electrical contact with the divided ring 15, connecting the switch
lever 16, and battery circuit, when the mouthpiece 1ª is screwed up, substantially
as described.
2. In a telephone combination constructed as described in Claim 1, the flexible
ear tube attached to ferrule 19, or 19' which collects the sound waves from
between the tympans, operates the switch lever, and by means of said ferrule, holds
the telephone in position within the case, in the way and manner described.
3. In a telephone combination constructed as described in Claims 1, and 2, the
use and employment of the cramp screws and divided segmental plates with the
method of coupling the insulated wires thereto so as to establish electrical
connection with the microphone switch, and battery circuit, avoid soldered joints,
and permit speedy removal and replacement of the inter-acting parts, as described.
4. In a telephone combination constructed as described, the particular method of
electrically connecting the microphone employed by means of the contact screw 7"
strips 8, 8" or equivalent, and cramp pins 10, 10°, thereby avoiding loose wires.
Dated Danambar 1+ 1900
FRANCIS M. ROGERS,
A cont