Year: 1886

page_text: I, JAMES FRASER, of the Atlas Works, Tenter Lane, Leeds, in the County of
York, Electrical Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates, first, to the outer casing or carrier of the transmitters and
receivers of mechanical telephones, and second, to the means or apparatus employed
for manufacturing the same.
Instead of making the outer casing or carrier (containing the diaphragm) of
wood as has been hitherto done I form it of metal, preferably of thin sheet brass;
and it consists of two thin circular concavo-convex plates provided with flanges
for bolting them together. Between the flanges a vulcanized fibre perforated
diaphragm is fixed for receiving and transmitting the sounds. The plates are
fastened together with their concaved surfaces facing each other. The concavity
of the back plate is by preference made deeper than the front one, and is of a
shape or contour to correspond with the convexity assumed by the diaphragm when
held in tension by the strain of the line wire. In the centre of the back or deep
plate is a hole through which the wires are passed to the diaphragm, and in the
shallow or front plate is an opening or orifice in or to which is inserted or fastened
a bell shaped mouth piece. The metal receiver or transmitter may be mounted
and attached to a wooden block by two or more metal rods or pillars so arranged
that only a portion of the wooden block comes in contact with the convex portion
of the back plate.
By forming the carrier of metal, and constructing it as herein described the
articulation of the telephone is greatly increased.
The concavo-convex plates may be stamped or pressed into shape by any con-
venient means, but I prefer employing the following apparatus.

page_text: Two metal blocks or chucks are employed having recesses formed in their faces
to correspond with the convexity or outer contour of the circular plates. These
blocks are in turn mounted on the spindle of a lathe and the thin metal plate
bolted to them. The lathe is set in motion, and a round or bull nosed blunt tool,
carried on the sliding tool rest is then brought up to the plate, and traversed
forwards and inwards until the plate is moulded or pressed into and made to fit
the recess in the block or chuck.
Although the plates forming the outer casing are described as being circular
I would have it understood that they may be made in any other convenient form
and pressed into shape.
WM FAIRBURN HART,
Agent for the Applicant.

page_text: Improvements in or relating to Transmitters and Receivers for
Mechanical Telephones, and in the Means or Apparatus for
Manufacturing the same.
I, JAMES FRASER of the Atlas Works, Tenter Lane, Leeds, in the County of
York, Electrical Engineer, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly. described and ascer-
tained in and by the following statement:-
Hitherto the outer casing's of telephonic transmitters and receivers have been
made of wood, but as louder musical notes can be obtained from brass instruments
than from stringed ones, so I have found by experiment that when the casing is
formed of metal the articulation of the telephone is greatley increased and its
effeciency enhanced.
This invention relates first to constructing the outer casing or carrier of the
transmitters and receivers of mechanical telephones of metal, and second to the
means or apparatus employed for manufacturing the same.
And in order that my invention may be more completely understood reference is
given to the accompanying drawings on which Fig. 1 is a sectional elevation and
Fig. 2 a front elevation of a telephone constructed according to my invention
Figs. 3, 4, 5, and 6 are respectively sectional and front elevations of apparatus for
manufacturing the same Fig. 7 is a detail showing mode of attaching line wire to*
the diaphragm.
A is the outer casing or carrier of a receiver and transmitter of a mechanical
telephone, which is made of metal, preferably of thin sheet brass instead of wood
as hitherto, and it consists of two thin circular concavo-convex metal plates a, a',
provided with flanges a³, a³, for bolting them together as shown at a. What
I mean by concavo-convex plates, are plates recessed or dished so as to be hollow
on the surfaces a, and a, whilst the opposite or outer surfaces a and a¹, protrude
or project in a round or spherical form as shown at Fig. 1 ; Between the flanges a³, a³,
is inserted and fixed a perforated vulcanised fibre or other suitable diaphragm B for
receiving and transmitting the sounds. The diaphragm is by preference (though
not neccessarily so) fixed in position by the same bolts, studs, or set screws, a* that
secure the flanges together. The circular plates a, a, are fastened together with
their concave surfaces a³, a faceing each other. The concavity as, of the plate a³,
is by preference made deeper than that in the front plate a, and is of a shape or
contour to correspond with the convexity assumed by the diaphragm when held in
tension by the strain of the line wire C. In the centre of the back plate a' is a
hole a', through which the line wire C. is passed when it is fixed (in position) to
the diaphragm. In the drawings the line wire is shown at right angles with the
face of the diaphragm, but when it is neccessary to carry the line wire parallel, or
nearly so, with the face of the diaphragm a wooden insulator of ordinary con-
struction may be fixed to and within the supporting block D round which the line
wire is passed so as not to come in contact with the block, and a hole or opening is

page_text: made at through which the wire issues, The ends of the line wire C may be
attached to the diaphragm of each receiver or transmitter in the following manner.
A small metal disc or plate b is provided with a hole in the centre of such a
diameter as will permit of the line wire passing freely through it, after which a
loop is formed by bending or doubling the wire over and then twisting it round
and soldering it on to the main strand as shown at Fig. 1. Through the loop thus
formed a pin b¹ is inserted for preventing the end of the wire being drawn through
the diaphragm and for holding it in position.
Instead of using the pin and twisting and soldering the wire as described in some
cases I employed the device shown at Fig. 7 in which bis the thin metal disc or
plate having in its centre a hole large enough to admit of the boss b formed on
the button 3 passing through it and the diaphragm. In the centre of the boss b³.
is a hole b¹ large enough to permit of the line wire C passing freely through it.
The outer end or portion of the hole b is countersunk as shown to receive a knot
or projection 65 that has been tied or formed and soldered on the end of the line
wire.
It will be readily understood that on the line wire being tightened the soldered
knot or projection 6 passes within the countersunk portion of the button b³ and.
thus makes a firm and neat connexion. In the centre of the front shallow plate a
is an opening or orifice as in or to which is inserted a metal bell shaped mouth
piece E. In the drawings I have shown at a Fig. 1. the plate a projecting
outwards, and made to fit into a recess, formed in the periphery of the mouth
piece and soldered in position. Although I have found this to be a very convenient
method of attaching these two pieces together, yet I wish it to be understood that
I do not limit myself to this mode of fixing as any other convenient method may
be adopted. The metal receiver and transmitter may be mounted and attached to
a supporting block made of wood, marble or any other suitable material formed
as follows. D is a patrass or block in which is formed a recess for receiving the
end of a short cylinder or tube d (also made of wood) marble or any other suitable
material) shaped at the opposite or free end to fit the outer contour or convexity
of the circular metal plate a¹. Two or more metal rods or pillars F may be employed
for attaching the metal plates a, a¹³, and perforated diaphragm B to the supporting
block. One end of each pillar F may be screwed at finto the patrass D as shown
or a set screw may be made to pass from the back of and through the patrass and
screwed into the end f of the pillar F whilst the opposite end receives the end of
one of the set screws a', thereby securely attaching the outer casing A to the
pillars F and fixing it in position. The block D to which the outer casing A is
attached may be fixed to a wall or other support and the line wire C. is attached
at each terminal to a receiver and transmitter in the manner described and drawn
to the required degree of tension in the ordinary way until the desired sound can
be transmitted from one receiver to the other without the aid of a battery or any
additional means. The concavo-convex plates a. a¹, may be stamped, pressed or
moulded into shape by any convenient means, but I prefer employing the apparatus
shown at Figs. 3. 4. 5, and 6 which consists of two metal face plates or chucks G
and H. having concave recesses g and h respectively formed in their faces to
correspond with the outer contour or convexity of the circular plates a, a¹. These
chucks are in turn screwed in turn at g* and * on the spindle of a lathe and are
then ready for receiving the thin metal plate or disc out of which one portion of
the casing is to be formed. The plates or disc having been punched or cut to the
required size and the bolt holes made in it, it is then fixed to the face plate by set
screws which are inserted in the tapped holes g¹h'. The lathe is then set in
motion and a round or bull nosed blunt tool mounted on a compound sliding tool
rest (carried on the lathe gantry) is then brought up to the plate or disc and
traversed forwards and inwards until the plate or disc is moulded or pressed into
and made to fit the matrix g or of the face plate. It will be readily understood
when the operation of pressing the disc or plate into the matrix has been performed,
that the portion of the plate or disc at the bottom of the recess will be slightly

page_text: thiner than on the flanges. And by having facings g² h² of the exact diameter
and width of the flanges a³ a³ a gauge is thus provided for finishing the plates a, a
up to a standard size. Also, if the smaller portion of the recess is made a little
deeper than the depth of the projection a³ the operator is enabled to turn and face
the end of such projection ready for the reception of the mouth piece, without
removing the pressed or moulded disc from the face plate. The hole h³ in the face
plate H is the same diameter as the hole a' in the plate a¹ and thus ensures that
hole always being made the same size.
Although I have described the plates a. a¹ forming the outer casing A as being
circular I would have it understood that they may be made in any other convenient
form and pressed into shape by any ordinary means, but I have found that the
circular form is the most convenient to manufacture.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
First. The manufacture and use of a receiver and transmitter for a mechanical
telephone consisting of two flanged concavo-convex metal plates mounted and
attached to supporting blocks by rods, or pillars and having a perforatod diaphragm
inserted and fixed between the flanges of the said metal plates to which the line
wire is attached by means of a pin or button substantially as described and
illustrated.
Second. In a receiver and transmitter of a mechanical telephone and in com-
bination with a perforated diaphragm the moulded or pressed casing or holder
formed of two flanged concavo-convex metal plates bolted together with their
concave surfaces faceing each other and having the diaphragm inserted and fixed
between them; and provided with suitable openings or orifices for the admission
and insertion of the line wire and mouthpiece substantially as herein described and
illustrated.
Third. The receiver and transmitter of a mechanical telephone as a whole
constructed and arranged as herein described and illustrated.