IMPROVEMENTS IN AND RELATING TO TELEPHONE TRANSMITTERS to be as follows:
Year: 1884

page_text: I GEORGE LEE ANDERS, of Queen Victoria Street, London in the County
of Middlesex Electrician do hereby declare the nature of said invention for
"IMPROVEMENTS IN AND RELATING TO TELEPHONE TRANSMITTERS
to be as
follows:
"
My invention relates to telephone transmitters and has for its object to dispense
with the diaphragms, tympans, sound-boards and the like heretofore used in
instruments of this class.
My said invention consists essentially in utilizing engine coke for varying the
electric current in a telephone circuit. Engine coke which is a good conductor of
electricity is very advantageous for this purpose, its light and porous nature
enabling it readily to take up any vibrations in its vicinity.
In carrying my said invention into practice I provide a cup-shaped pieco of
engine coke; I prefer this form for the coke, as 1 may then, if desired, dispense
with a mouth piece the concave side of the said piece of coke collecting the sound
waves and causing them to be concentrated thereon.
Instead of the cup-shaped piece of coke I may use a piece of coke in a rough
state.
To the said piece of engine-coke I attach a loose contact piece of good conducting
material, as in the well known " Hughes" Microphone, such as platinum or carbon.
This contact piece is preferably of cylindrical shape and provided with one or
more points to bear upon the coke. The said contact piece may be mounted on a
light spring of conducting material or it may be mounted on a swinging arm,
arranged sufficiently out of the perpendicular to cause the contact piece to bear
lightly against the coke.
When the instrument is in circuit one end of the conducting wire is connected to
the said spring or swinging arm and the other end to the piece of coke.
I sometimes tix before the piece of coke a bar of conducting material on which
are fixed pins or their equivalent. The said pins are placed at such a distance
from the coke, that a piece of carbon or other suitable material placed thereon will
be just prevented from falling between the said pins and the coke, whereby a very
light contact is maintained between the said piece of carbon and the coke.
In making the cup-shaped pieces of coke I may form them from rough lumps or
I may place a suflicient quantity of coal in a mould and heat the same allowing
only a portion of the gas to be expelled.
It is obvious that I may arrange the contact pieces in any suitable manner to
bear upon the coke without departing from the nature of my invention.
HASELTINE, LAKE & Co.,
For the Applicant.

page_text: I, GEORGE LEE ANDERS, of Queen Victoria Street, London, in the County
of Middlesex, Electrician, do hereby declare the nature of said invention for
"IMPROVEMENTS IN AND RELATING TO TELEPHONE TRANSMITTERS
" and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
My invention relates to telephone transmitters and has for its object a novel
construction of such instruments whereby I am enabled to dispense with the
diaphragms, tympans, sounding boards, or like parts heretofore used in the same.
I have discovered that the kind or quality of coke known as hard or engine
coke, which has a peculiar cellular structure and encloses gas within its pores, is
very advantageous for telephonic purposes, as it is a good conductor of electricity
and its light and porous nature enables it readily to take up, or be affected by, any
vibrations in its vicinity, and I utilize this material for the purpose of my invention
as follows, that is to say:
My said invention consists chiefly in a telephone transmitter which is devoid of
any such contrivance as a diaphragm, tympan, or sounding board, and which is
essentially constituted by the combination of a block or piece of hard or engine
coke and a piece or pieces of metal or other good conducting material arranged in
any suitable manner in loose or microphonic contact, that is to say, the electrodes
should be kept in contact with each other in the loose manner which is character-
istic of the well known "Hughes" microphone.
The shape of the hard or engine coko is not of great importance and it would be
pos-ible to use this material in the form of rough blocks or lumps, but in carrying
my invention into practice I prefer to have the piece of coke so formed and
arranged as to present a concave or cup-shaped surface to the mouth of the person
using the instrument, as this concave surface collects and concentrates the sound-
waves and enables me to dispense with the ordinary mouth-piece if I find it
desirable to do so.
My invention is illustrated in the accompanying drawings, in which.
Figure 1 is an elevation of my improved transmitter, mounted upon the lid or
cover of a suitable box or case, showing the said box or case open.
Figure 2 is a vertical section on the line x, x, Figure 1, showing the said box or
case closed.
The remaining figures illustrate various modifications of the instrument shown
in Figures 1 and 2.
Like letters indicate the same parts throughout the drawings.
A is a box or case of wood or other suitable material, B is the lid or cover of the
same, a is the block or piece of hard or engine coke, which is arranged opposite thic
aperture B in the lid or cover B. This block has cemented to its periphery a
piece b of cloth or other suitable material, which forms a flange around the block
and affords the means for securing it in place by the aid of the ring c. The latter
is formed of ebonite or other suitable insulating material and is secured upon the
cloth band to the box-lid by screws d or other means which will permit its ready
removal when required.
1 arrange the metal or other contact piece or pieces in combination with the
block a as follows, viz, e is a metal bar or plate supported by the studs or posts f
which are secured in the box-lid in such a position that the said bar extends
centrally across the block cr piece w. g is a screw adjustable in the said bar; his
a metal disc or button which has in it a small recess or cavity to receive the

page_text: point g of the screw. This disc or button is not fixed on the coke, but is held in
loose contact therewith by the screw g, as clearly shown in Figure 2. By the
adjustment of tho said screw the condition of the contact between the electrodes
may be varied as desired.
The said block a and the parts g, h are included in the primary circuit of the
inductorium placed inside the box at i, (as shown in Figure 1), the secondary coil
of this inductorium being included in the main line or circuit.
Figure 3 is a rear elevation, and
Figure 4 a vertical section (on the lino y, y Figure 3) of another instrument in
which my said invention is embodied.
In this instrument the concave or cup-shaped block or piece a of coke is secured
in place by the aid of the devices described with reference to Figures 1 and 2, and
a metal bar or plate e is supported by posts f extending centrally across the said
block as above described. But in this instrument the loose contact piece is a small
cylinder formed of any suitable metal or other material; it rests on two pins or
studs,, projecting from the inner side of the bar e, that is to say, this contact
piece is supported partly by the said pins and partly by the coko in such a
imanner that it bears against the surface of the coke with very slight pressure,
thereby ensuring that relative condition of the electrodes termed loose or micro-
phonic contact.
In Figure 5 I have shown in transverse section another modification of my
invention, in which the piece of coke a is balanced and supported above the mouth-
piece m on the point of the adjustable screw pin or rod n, which is fitted to work
through a screw-threaded aperture or nut at m¹; if the mouth-piece m is not mado
of insulating material, the screw-threaded part must be formed of insulating
material and may be a tube or bush fitted in the aperture at m' as shown. It will
be seen that the current passes through the rod or pin n and that the part of the
circuit where the microphonic contact is to be maintained is at the point of the said
rod or pin on which the coke a rests. It is obvious that, as the only pressure at
the point of contact is that due to the weight of the coke a, this pressure will be
very slight. I may, however, if necessary, provide for diminishing this pressure by
magnetic attraction as follows; p is a magnet and p¹ is its armaturo which is
attached to the upper surface of the coke. The attraction of the magnet for its
armature will always tend to raise the coke and diminish the pressure at the point
of contact; by turning the screw n the coke a may be adjusted vertically to
increase or diminish the effect of the magnet and thereby regulate the contact
pressure as desired. If necessary the magnet may be made adjustable by a screw
or otherwise.
In Figure 6 I have shown in transverse section a further modification of my
transmitter. In this modification I provide for maintaining the loose or micro-
phonic contact, as follows, that is to say, I form an annular cavity or groove in tle
part of the box or case above the mouth-piece m. In this cavity I place two semi-
circular metal contact pieces or electrodes 9 insulated from each other at g'as
shown in plan in Figure 7. Above these metal semi-circular pieces I place in the
said cavity granulated or powdered coke or the like as shown at rand upon this
material rests the concave or cup-shaped piece a of hard or engine coke. It will
be seen that the current passes from one to the other of the pieces y through the
granulated material at r and through the coke a and that the loose contact exists
between the entire surfaces of the semi-circular metal pieces and the coko or other
material lying on them.
I may further modify the construction of my instruments by mounting a contact
piece on a light spring of conducting material or on a swinging arm or bar arranged
sufficiently out of the perpendicular to cause the said contact piece to bear lightly
against the coke. When the instrument is in circuit, one end of the conducting
wire is connected to the said spring or swinging arm or bar and the other end to
the piece of coke.

page_text: I wish it understood that I do not claim generally or irrespectively of the
particular features or devices hereinabove specified, the employment of coke or
carbon in telephonic instruments, as I am aware that these materials have been
used, in a granulated or pulverized condition, in suitable receptacles and also in the
form of buttons, discs, balls, or the like in various forms of instruments, in
combination with diaphragms or tympans for varying the resistance of the circuit
in correspondence with diaphragmatic or tympanic vibrations.
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.
The use of a block or piece of coke in a telephone transmitter constructed
without a diaphragm or tympan, substantially as, and for the purposes, described.
HASELTINE, LAKE & Co.,
For the Applicant.