Improvements in Telephones.
Year: 1893

page_text: Date of Application, 16th Feb., 1893.
Complete Specification Left, 19th Oct., 1893-Accepted, 25th Nov., 1893
PROVISIONAL SPECIFICATION.
Improvements in Telephones.
I Sir CHARLES STEWART FORBES Baronet, of 28 Queens Gate Terrace
London S.W. East India Agent, do hereby declare the nature of this invention to
be as follows:-
My invention consists in improvements in telephones and is carried out as
follows: A horse-shoe or bent steel permanent magnet is forged so that the two
extremities or poles, take the form of rings. These are bored out, screwed and
fitted with two tympans which are held in position by ebonite or equivalent
insulating rings. Between the two poles formed as described is secured a brass or
other ring perforated and formed or fitted with an ear piece, trumpet, or trumpets,
one of which (when two are employed) may, if desired, be used as a mouth piece,
or the instrument may be fitted with a cone shaped trumpet or sound director for
loud speaking effects. The brass ring is preferably forked or otherwise so formed
as to permit it to carry a horse-shoe or ring-shaped permanent magnet having
preferably adjustable soft iron pole pieces which carry inducing bobbins, connecting
line and earth.
An instrument constructed thus may be used either as transmitter or receiver
and with or without a microphone. I do not bind myself particularly to the shape
of the magnets employed, as these may be varied to suit required conditions,
provided a nearly closed magnetic chain is maintained through the tympans. The
inducing bobbins may be connected in series, parallel, or independently to separate
induction coils and lines.
Dated February 16 1803
FRANCIS M. ROGERS,
Agent.
COMPLETE SPECIFICATION.
Improvements in Telephones.
I, Sir CHARLES STEWART FORBES Baronet of 28 Queens 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 improvements in telephones, and is carried out as
follows:-
A horse-shoe or bent steel permanent magnet is forged so that the two extremities
or poles take the form of rings. These are bored out, screwed and fitted with two
tympans, which are held in position by ebonite or equivalent insulating rings.
Between the two poles formed as described is secured a brass or other ring
perforated and formed or fitted with an ear piece, trumpet or trumpets, one of
which (when two are employed) may, if desired, be used as a mouth piece, or the
instrument may be fitted with a cone-shaped trumpet or sound director for loud
speaking effects.
The brass ring is preferably forked or otherwise so formed as to permit it to
carry a horse-shoe or ring-shaped permanent magnet having preferably adjustable
soft iron pole pieces, which carry inducing bobbins, connecting line and earth. An
instrument constructed thus may be used either as transmitter or receiver, and
with or without a microphone.
I do not bind myself particularly to the shape of the magnets employed, as

page_text: these may be varied to suit required conditions, provided a nearly closed magnetic
chain is maintained through the tympans. The inducing bobbins may be connected
in series, parallel or independently, to separate induction coils and lines.
To enable my invention to be better understood, reference is made to the
accompanying drawing in which :-
Fig. 1. is a sectional plan on line A B (Fig. 2).
Fig. 2. is a side elevation, the side of case being removed.
Fig. 3. is a front elevation, shewing double ear tubes.
Fig. 4. is a diagram shewing the inducing bobbins coupled up in parallel.
Fig. 5. is a diagram shewing the inducing bobbins connected to separate lines.
In the drawing 1, is a box, preferably formed of wood, the base of which is
perforated with bushed screw holes 2, terminals 3, are mounted thereon.
Secured to the case or box by the screw and nut 4, and by the screwed metal
flange 5, engaging with the mouth piece 6, forming part of brass or other packing
ring 7, or in any equivalent manner suitable for the purpose are two permanent
steel magnets. One of these 8, is formed at its upper ends into two rings 9, these
are bored, recessed, and threaded as shewn.
A tympan 10, of thin ferrotype iron is inserted in each recess and held in position
by non-magnetic rings of ebonite or the like substance, or by brass or non-magnetic
rings 11.
Carefully fitted between the rings 9, is a non-magnetic metallic packing ring 7,
which is held in position by the screws 12, tapped into it and placed at suitable
intervals round the rings 9. This ring, as well as the nozzle, 6, secured to the case
by the screwed flange 5, is cored out as shewn in dotted lines Fig. 2. The ring 7,
also carries, or has a forked spur 13 formed upon it, to which is fixed by pinning as
shewn, another permanent magnet 8, the poles 13' of this magnet are preferably of
oval shape and are bored out as at 14, slotted and fitted with soft iron extensions 16,
a pin 17 is driven into each extension and engages with the slot 15, the extension
being thereby prevented from turning round.
To enable the extensions 16, to be accurately adjusted with regard to the
tympans 10, each end is tapped as at 18, a screw 19, having a bevelled head
sufficiently large to cover each hole 14, engaging therewith, these screws are cross
cut, so as to be operated by an ordinary screw driver, and are held in position
by the plate 20, fastened by screws 121, to the magnet poles.
The bobbins 21 are filled with suitably sized insulated wire 22 connected in
series or parallel and secured to the terminals 3.
When mounted up in a case as shewn, two small holes 23, having removable
metallic covers 24, are bored therein, opposite the screws 19, for the purpose of
adjusting them by means of a screw driver. The operation of the improved form
of telephone described is as follows:-
In the magnet 8, the ring shaped poles 9, have the effect of polarizing the edges
of tympans 10, secured therein, while the magnet 8, carrying the inducing
bobbins 21, the wire on which connects the line and earth, produces a very powerful
magnetic effect upon the centre of each tympan, when actuated directly, or by
means of a microphone with or without an induction coil, the polarity being of
opposite sign to that induced upon the edge of each plate by the rings 9 of
magnet 8.
Since the tympans are only separated by the narrow non-magnetic ring 7, it
follows that their vibrations, which are influenced by the current flowing round the
coils of the bobbins, mounted upon the extensions 16, take place in a powerful and
nearly closed magnetic field, resulting in loud clear speech, which is conveyed to
the listener by the cored opening, communicating with the funnel or other shaped
mouth piece 25. This may be replaced if desired by a bifurcated tube, as see
Fig. 3, in which case one tube may be employed as a mouth piece for sending the
message, the other for receiving the same.
The wire coils of the inducing bobbins. may be coupled in series as in Fig. 1. 2.
in parallel as in Fig. 4, or each coil may be coupled to a separate line as shewn in
F.

page_text: Fig. 5, thereby enabling one instrument to operate or be operated by two distinct
lines. The instrument may be used as transmitter or receiver, and with or without
a microphone or microphones and induction coil or coils.
I do not bind myself to the exact shape size or relative proportion of the magnets
employed; for instance the magnet 8ª, may be of the same size as the magnet 8,
and again the magnet 8, may consist of a plain but narrow horse-shoe, having rings
for its poles. The magnets may also be constructed of several strips or laminæ of
steel bound together by riveting or in any equivalent manner.
I do not broadly claim the use of double tympans supported and polarized on
their edges by ring shaped magnetic poles having the same sign, neither do I lay
claim to the particular form of extensions and adjustments shewn, except when such
are used in combination with two distinct permanent magnets, one of which has
ring shaped poles in which the tympans are so placed as that their edges are
polarized in a direction opposite to each other, the other permanent magnet being
so arranged as to polarize the centre of each tympau in a direction opposite to the
edge. The extensions and adjustment therefor, may be replaced by any suitable
device having a like effect.
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. The improved telephone constructed and operating in the way and manner
described..
2. In a telephone instrument the combination of a permanent magnet having
ringed shaped poles 9, of opposite sign for holding and polarizing the edges of
tympans 10, secured as described. The cored non-magnetic ring 7 and fork 13,
which supports the magnet 8*, carrying soft iron adjustable extensions 14, having
bobbins 21, filled with wire connecting line and earth, for oppositely polarizing the
centres of said tympans, the respective parts co-operating for the purpose of pro-
ducing speech which is collected from between the tympans by an ear trumpet,
tubes or equivalent, by the means and in the way and manner shewn.
3. In a telephone having two independent magnets and inducing bobbins, the
particular construction whereby the tympans are placed in a nearly closed magnetic
field, formed by the joint action of said magnets, substantially as shewn and
described.
4. In a telephone having two independent permanent magnets, one of which
polarizes the edges of each tympan plate, and the other the centres, in the manner
shewn, the particular method of connecting the inducing coils so that one instrument
will operate or be operated by two distinct lines.
Dated October 19th 1893.
FRANCIS M. ROGERS,
Agent.