Year: 1887

page_text: Date of Application, 16th Mar., 1887.
Specification Accepted, 19th Apr., 1887
[Communicated from abroad by ARTHUR M. PHELPS, residing at Seabrook, in the
County of Prince George and State of Maryland, United States of America,
Electrician.]
I, ALFRED JULIUS BOULT of 323 High Holborn, in the County of Middlesex,
M.I.M.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:
This invention relates to certain new and useful improvements in telephones but
more particularly to that class known as magnetic electrical and in which sounds
are received and transmitted by means of vibratory diaphrams electrically connected,
the object of the present improvements being to secure an instrument that will be
exceedingly sensitive that will respond quickly and clearly to the tones of the human
voice or other sounds; and it consists essentially of a telephone provided with a
diaphragm having a core or bar attached end wise to the centre of said diaphragm; and it
further consists in holding said bar loosely within a central opening formed in a wire
spool and placing a dividing sheet between the enlarged ends of the core and
permanent magnet.
The peculiar construction and arrangement of the various parts will be more fully
pointed out and described in the specification and claims reference being had to the
accompanying drawings in which :-
Figure 1 is a longitudinal sectional view of this invention showing the parts in place
with wire attachment and ear-piece at end.

page_text: mouth piece on side.
Figure 3 is an end view of the handle and
Figure 4 is a detail sectional view of core and magnet.
Similar letters refer to similar parts throughout the drawings.
Referring to the drawings, A, represents a hand receiving case formed of any
suitable material and having a central longitudinal opening, one end of said case being
formed with a circular enlargement cup shaped and hollow (designated as A¹) said
enlargement being screw-threaded on its outer edge to receive a screw-threaded cap
or ear-piece B having a flaring opening. A diaphragm C of suitable vibratory
material having a bar or core D made preferably of soft iron, centrally attached by
its end thereto is placed within the cup shaped piece B above a coiled or wound wire
spool E said spool being rigidly secured within said cup A¹ and provided with a
central opening E through which the bar or core Dis arranged to move freely endwise
so that the slightest variation of current or vibration of diaphragm Caffects and moves
said bar. The ends of the wire, or wires, passing around spool E are connected by
wires a to binding posts b.
The inner end of cord D is flanged outward and abuts closely to the flanged end of
the permanent magnet F the object of this construction being to provide a larger
magnetizing surface between the ends of core D and magnet F. Magnet F extends
lengthwise from the end of core D through the handle of case A and is adjustably
secured by means of a set screw d' passing through the end of plate e as shown in
Figure 1 said plate being rigidly attached to the end of handle A and having a
threaded hole to accomodate said set screw d¹. A friction guide or washer a¹ formed
of rubber or other suitable material is placed around magnet F below the bottom of
cup A to render magnet F easily adjusted. An anti sticking cap or sheet & formed
of suitable non-magnetizing material such as very thin sheet brass or copper is placed
between the flanged ends of core D and permanent magnet F said cap or sheet being
secured to the inner face of cup A¹ or to the end of magnet F the purpose of this sheet
being to prevent sticking of the opposite faces of the flanged parts of said magnet and
core, should they come in contact from any cause.
Between the thumb piece of screw bolt d and the plate e a screw threaded check
nut is loosely secured, by means of which the bolt d' is held tightly in place at any
desired point whereby the magnet F is securely held.
The arrangement of the different parts as a transmitter is shown in Figure 2 in
which the flaring mouthpiece is shown attached to the side of case G the diaphragm
and core and magnet made to work transversely in said case the inner end of said
case G being arranged with a set screw f by means of which the magnet is
adjustable transversely. The core D may be hollow if deemed desirable or advan-
tageous and under certain constructions of the telephone the flange of both bar D
and magnet F can without detriment be dispensed with as shown in Figure 4 and
also the sheet d.
Instead of using a permanent magnet any equivalent such as an electro magnet
may be used the same being rendered adjustable by any suitable means, or in the
same manner as the permanent magnet which magnet may also be rendered adjustable
by any preferable means equivalent to that shown.
If desirable a small spiral spring or washer of any suitable pliable material, may
be placed between the end of bar D and diaphragm C which by aid of a small screw
passing through the diaphragm into the bar will form an adjustment for said bar.
If desirable this telephone can be used as a "battery telephone" in which case a
bar of steel or iron is substituted for the permanent bar magnet and is rendered
adjustable in like manner, or any suitable equivalent means.

page_text: Having now particularly described and ascertained the nature of the said invention
as communicated to me by my foreign correspondent and in what manner the same is
to be performed I declare that what I claim is :-
1. A telephone transmitter and receiver provided with a permanent or electro
magnet in line with a core or bar (made preferably of soft iron) within a wire spool
electrically connected a diaphragm of suitable vibratory material centrally joined to
one end of said core and the opposite end in close proximity to one end of a permanent
or electro magnet with an intervening cap or disc, the whole surrounded with a
suitable case substantially as set forth.
2. A. telephone constructed with a case A provided with a cup shaped end A' on
which flaring cap B is secured under which is secured a vibrating diaphragm C to
the centre of which a core D is endwise secured, a wire spool E centrally surrounding
said core, a permanent magnet F held in line with core Da dividing sheet the
friction guide or washer a the set screw the plate e and check nut in combination
with the wires a and the binding posts substantially as shown.
W. P. THOMPSON & BOULT,
Agents.