Year: 1887

page_text: Date of Application, 23rd Nov., 1887
Complete Left, 5th Dec., 1887
Complete Accepted, 6th Jan, 1888
RESERV
[Communicated from abroad by JOHN POWELSON SUNDERLAND, of 426, Green
Avenue, Brooklyn, New York, United States of America, Mechanical Engineer,
and DOMINGO MIGUEL MONJO, of 379, Sackett Street, in the same City,
Gentleman.]
I. WILLIAM HENRY MUNNS, of 54 Fleet Street, London, E.C., Patent Agent do
hereby declare the nature of this invention to be as follows:-
The invention consists of improvements in mechanical telephones whereby sounds
can be clearly transmitted in all states of the atmosphere.
The diaphragm consists of a central ply covered with waterproofed leatheroid or
other material used for covering compound diaphragms. On the front of the extended
diaphragm is placed a hollow button with extended flanges. This button is filled with
non-conducting material except a central perforation extending through the said non-
conducting material and the button. To the outside of the button is secured directly
or indirectly the line wire so as to bring a strain to bear on the diaphragm. The line
wire is in preference composed of several twisted strands of wire round a core of bad
If
conducting material and the whole covered with some bad conducting material.
desired, two or more wires attached to different diaphragms may be connected
together by a metal bar of a shape adapted to securely fit on the wires.
Dated this 23rd day of November 1887.

page_text: S. nu
plate removed.
Teat VICWS
He uapulagins as SHOW WIT
Fig. 6 is an enlarged detail section showing the wire attachment of Fig. 2.
Fig. 7 is a diagrain face view showing four telephones in circuit, the wires being
partly broken away.
A, indicates the frame or casing of the telephone. This frame is usually of wood,
but may be of papier mache or other material. The casing is generally a short
cylinder having a cover. B at its front, which cover fits a recess in the casing.
A diaphragm or disc C Fig. 1 extends across the casing and is firmly clamped at its
edges between the cover B and casing A, the cover being held down by screws or in
other suitable manner.
In the front of this diaphragın there is a metallic plate D covering a part of the
central portion of the diaphragm. In front of this plate there is a metallic shell or
button E, the shell being filled with plaster of Paris or other non-conducting
material F. A hole extends through the button from front to rear, and a headed pin
or bolt G passes through this hole. The transmitting wire H, is connected to the rear
end of this bolt.
The metallic plate D may be omitted and the edge of the button E turned out or in
to give a broad bearing on the diaphragm as shown in Fig. 3.
These wires are secured
In the modification Figs. 3 and 5 the diaphragm is supported on its rear surface by
wires I, I, which extend across the casing from side to side.
at their ends to pins or screws in the casing.
In the modification Fig. 2, the diaphragm C¹ is composed of separate plies of paste-
board, or mill board, or of woven wood fiber covered on the surface with leatheroid or
other suitable material used for the covering of compound diaphragms, and the covering
is waterproofed.
The wire H¹ Figs. 2, 4, and 6 is attached to an insulating piece. This insulating
piece consists of a band L of metal surrounding a short cylinder of rubber M, said
rubber being mounted on an axis N, which is sustained by loops O in the side of the
casing. The wire H¹ extends from the band L through a hole in bolt G at such a

page_text: distance from the diaphragm as to put a strain on said bolt G and thereby on the
diaphragm.
The rear plate A¹ of the casing A is of metal, board, or pasteboard, and is readily
removable. This rear plate may be omitted entirely.
The wire preferred is a small twisted cable protected by a covering.
The telephones a and b Fig. 7 may be connected by a wire H' extending from the
sides of the casing or from the rear.
Where two telephone wires belonging to separate lines are in proximity, (see Fig. 7)
a bar P may be extended from one to the other, and all the telephones will be
thrown into use as receivers when one of the series is spoken to. A good form of
bar P is shown in the drawing, the bends R resting on the wires when found desirable.
Curves S S in the wires are effected by means of insulated hangers, as is well known
in this art.
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. The mechanical telephone having a stretched diaphragm and an insulating
button of the described kind in front of said diaphragm, the line wire being connected
to said button.
2. A diaphragm for mechanical telephones having a central ply covered with
leatheroid or other suitable substance used for the covering of compound diaphragms,
which covering is waterproofed.
3. The line wire connected to an insulated coupling at one side of the casing, and
connected to the diaphragm by a coupling under tension as described.
4. The wires of several telephones connected to the casings in the manner described,
and a connecting bar with curved ends for coupling the same.
Dated this 5th day of December 1887.
W. H. MUNNS.