Improvements in Mechanical Telephones.
Year: 1888

page_text: Date of Application, 12th Sept., 1888
Complete Specification Left, 12th June, 1889-Accepted, 13th July, 1889
PROVISIONAL SPECIFICATION.
Improvements in Mechanical Telephones.
I, GEORGE FREDERICK REDFERN, of the firm of G. F. Redfern & Co., the General
Patent Office, No. 4, South Street, Finsbury, in the County of Middlesex, Patent
Agents, do hereby declare the nature of this invention (a communication from abroad
by George Frederick Shaver, of New York, in the County and State of New York,
United States of America) to be as follows:-
This invention relates to devices employed in transmitting speech and has for its
object the provision of a mechanical telephone of greater vibratory power than has
been heretofore attained, and, of means for focussing the sound waves thrown off
from the diaphragm reflector placed opposite the mouthpiece, and of the particulars
hereinafter described.
To attain the desired end my invention consists in the construction and arrangement
of parts as and for the purpose set forth.
In carrying out the invention I employ a frame case or box, preferably square and
resting upon two parallel base bars or string pieces extending a short distance beyond
the sides of the box. The back of the box which serves as a sounding board and
which rests as stated upon string pieces is, by this construction, held away or raised
from any surface to which my telephone box may be placed or attached, as for
instance a wall, the instrument being secured to the same however by screws or nails
inserted through the projecting ends of the string pieces. At the corners of my
box are placed four corner posts which are provided with slots adapted to receive and
securely hold the ends of the thin sideboards of my telephone box.. Four flat bars
or string pieces forming a rectangular frame are placed upon the corner posts and
side boards and behind the inner face of my sounding board which forms the face of
my box, for the purpose of strengthening my box, the various parts are bound
together by bolts or screws passing through the sounding board and string picces into
the corner posts. Preferably placed upon the sounding board, are one or more
exterior sounding boards separated by narrow strips the sounding boards being
connected together by means of four sounding posts. A concentrating mouthpiece
constructed of vibratory material may or may not be fitted to one of the sounding
boards for convenience in use.
A diaphragm (constructed preferably in two parts) of compressed fibrous material,
as for example, "Leatheroid" or "Vulcanized Fibre" which I find peculiarly adapted
for use in this connection, is fastened to the inner side of the sounding board by the
following means. A diaphragm plate is secured by screws to the sounding board and
is preferably depressed or concave at its centre and adapted to be connected with a
line wire by being provided with a central opening in order to receive a concave or
dome-shaped reflector of parabolic or hemispherical section provided with a flanged
edge placed between the diaphragm plate and sounding board. The sounding board
is under tension while in use and vibrates simultaneously with the diaphragm.
A button constructed of non-metallic material is placed under the diaphragm
reflector and the elongated shank of the same serves to provide a means for attaching
my line wire and my diaphragm reflector together. The button and elongated shank
is made of non-metallic inaterial in order to do away with the resonance experienced
in the use of metals and being lighter secures better articulation. The line wire is
constructed of several wires twisted about a fibrous core the object of the core being
not only to make the completed wire more flexible and therefore more responsive to
vibrations, but it also acts as a damper and deadens the resonance of the surrounding
steel wires thereby greatly improving the articulation. The bottom edges of the
side boards of my box are ordinarily cut away to allow the sound vibrations
BARR

page_text: The action of the instrument is as follows ;--When the vibrations of the line wire
reach the diaphragm reflector it is thrown into vibration and the sound waves thrown
off from its sides are brought to a focus at the centre of the opening in the sounding
board and of the mouth piece. The diaphragm plate is also thrown into vibration
and being attached to the sounding board the three sounding boards (connected by
the posts) are simultaneously caused to vibrate. The effect of the combined sounding
boards and diaphragm vibrating in unison being to greatly increase the power or
loudness of the sounds emitted by the telephone.
Although I have described the diaphragm as constructed in two pieces yet it is
obvious that from one and the same integral material the diaphragm plate might be
formed and the line wire may be attached directly to the diaphragm reflector and the
interior sounding boards may also be dispensed with if desired. As it is evident that
many slight changes in the construction and relative arrangement of parts might be
resorted to without departing from the spirit and scope of my invention, I would
have it understood that I do not limit myself to the precise construction and arrangment
of parts described.
Dated the 12th day of September 1888.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Mechanical Telephones.
I, GEORGE FREDERICK REDFERN, of the firm of G. F. Redfern & Co., the General
Patent Office, No. 4.South Street, Finsbury, in the county of Middlesex, Patent
Agents, do hereby declare the nature of this of this invention (a communication
from abroad by George Frederick Shaver of New York, in the county and State of
New York, United States of America) 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 devices employed in transmitting speech and has for its
object the provision of a mechanical telephone of greater vibratory power than has
been heretofore attained, and, of means for focussing the sound waves thrown off
from the diaphragm reflector placed opposite the mouthpiece and of the particulars
hereinafter described.
To attain the desired end my invention consists in the construction and arrangement
of parts as and for the purpose set forth.
In the accompanying drawing..
Figure 1 represents a vertical section of a mechanical telephone constructed
according to my invention the section being taken on the line X X of figure 2.
Figure 2 is a front elevation, and,
Figure 3 is a side view of the telephone.
Figure 4 represents a view of the back of the instrument and,
Figure 5 is a detail view.
Like letters of reference indicate corresponding parts in all the figures.
In carrying out the invention 1 employ a frame A case or box preferably square
and resting, upon two parallel base bars or string pieces A' extending a short distance
beyond the sides of the box. The back of the box A3 which serves as a sounding
board and which rests as stated upon string pieces A' is by this construction, held
away or raised from any surface to which my telephone box A may be placed or
attached, as for instance a wall, the instrument being secured to the same however by
screws or nails inserted through the projecting ends of the string pieces. At the
corners of my box A are placed four corner posts A' which are provided with slots
. adapted to receive and securely hold the ends of the thin sideboards A² of my telephone
box as shewn in figures 2, 3 and 5. Four flat bars or string pieces B' forming a
rectangular frame are placed upon the corner posts A' and side boards A and behind

page_text: the inner face of my sounding board B which forms the face of my box, for the
purpose of strengthening iny box A; the various parts are bound together by bolis
or screws b passing through the sounding board B and string pieces B into the
corner posts A. Preferably placed upon the sounding board B are one or more
exterior sounding boards I separated by narrow strips i, the sounding boards A³ B
and I being connected together by means of four sounding posts Has clearly shewn
in the drawing. A concentrating mouthpiece C constructed of vibratory material
may or may not be fitted to the sounding board B for convenience in use.
::
A diaphragm D, E (constructed preferably in two parts) of compressed fibrous
material, as for example Leatheroid or Vulcanized Fibre" which I find peculiarly
adapted for use in this connection, is fastened to the inner side of the sounding
board B by the following means. The diaphragm plate D is secured by screws d to
the sounding board B and is preferably depressed or concave at its centre and adapted
to be connected with a line wire F by being provided with a central opening in order
to receive a concave or dome-shaped reflector E of parabolic or hemispherical section
provided with a flanged edge placed between the diaphragm plate D and sounding
board B. The sounding board B is under tension while in use and vibrates
simultaneously with the diaphragm D.
A button Ġ constructed of non-metallic material is placed under the diaphragm
reflector E and the elongated shank of the same serves to provide a means for attaching
my line-wire F and my diaphragm reflector E together. The button G and elongated
shank is made of non-metallic material in order to do away with the resonance
experienced in the use of metals and being lighter secures better articulation. The
line wire F is constructed of several wires twisted about a fibrous core the object of
the core being not only to make the completed wire more flexible and therefore more
responsive to vibrations, but it also acts as a damper and deadens the resonance of the
The bottom
surroundings steel wires thereby greatly improving the articulation.
edges of the side boards A² of my box A are ordinarily cut away to allow the sound
vibrations egress.
The action of the instrument is as follows:-When the vibrations of the line
wire Freach the diaphragm reflector E it is thrown into vibration and the sound
waves thrown off from its sides are brought to a focus at the centre of the opening in
the sounding board Band of the mouth piece C. The diaphragm plate D is also
thrown into vibration and being attached to the sounding board B the three sounding
boards B, A3 and I (connected by the posts H) are simultaneously caused to vibrate,
the effect of the combined sounding boards and diaphragm D E vibrating in unison
being to greatly. increase the power or loudness of the sounds emitted by the
telephone.
Although I have described the diaphragm D E as constructed in two pieces yet it
is obvious that from one and the same integral material the diaphgram plate might be
formed and the line wire F may be attached directly to the diaphragm reflector E and
the interior sounding boards I may also be dispensed with if desired. As it is evident
that many slight changes in the construction and relative arrangement of parts might
be resorted to without departing from the spirit and scope of my invention, I would
have it understood that I do not limit myself to the precise construction and
arrangement of parts described.
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 mechanical telephone the combination of a diaphragm, an apertured
sounding board under tension, extending entirely over and supporting said diaphragm
and a connecting line wire, substantially as set forth.
(2) In a mechanical telephone a supporting frame or case in combination with an
apertured sounding board extending over the entire front of said case and supporting
under tension a diaphragın connected with a line wire F attached beneath or back of
the said sounding board B substantially as herein set forth.

page_text: (3) In a mechanical telephone a supporting frame or case in combination with a
diaphragm and a sounding board under tension extending across the face of the said
diaphragm and forming a support therefor and provided with a central opening and a
concentrating mouth piece substantially as set forth.
(4) In a mechanical telephone having a sounding board extending across the face
of the telephone and provided with a central aperture, the said sounding board being
under tension while in use, the combination with the sounding board of a line wire
and a diaphragm secured to the inner or under side of the said sounding board and
adapted to vibrate simultaneously with the same.
(5) In a mechanical telephone the combination with a line wire of a diaphragm
connected with the line wire by means of a non-metallic piece or attachment G
extending rearward from the diaphragm substantially as set forth.
(6) A method of telephoning acoustically by means of two acoustic or mechanical
telephones, connected together by a cable wire' composed of several strands, twisted
around a fibrous core or damper substantially as set forth.
(7) In a mechanical telephone the combination of a frame or case, a sounding
board extending over the front of the said case and having a central aperture, a
diaphragm secured to the inner side of the same and a converging reflector as set
forth.
(8) In a mechanical telephone the combination of the string pieces A¹, side
boards A, sounding boards A³, B, I, corner posts A, mouth-piece C, reflector E,
diaphragm D, the line wire F, and sounding posts H, substantially as herein set
forth.
Dated the 12th day of June 1SSO
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.