IMPROVEMENTS IN TRANSMITTERS FOR TELEPHONES
Year: 1883

page_text: LETTERS PATENT to Thomas Myddleton Morriss of No 40 and 42 Queen
Victoria Street in the city of London for an Invention of "IMPROVEMENTS IN
TRANSMITTERS FOR TELEPHONES"
PROVISIONAL SPECIFICATION left by the said Thomas Myddleton Morriss
at the Office of the Commissioners of Patents on the 2nd August 1883.
THOMAS MYDDLETON MORRISS of N° 40 and 42 Queen Victoria Street in the
city of London "IMPROVEMENTS IN TRANSMITTERS FOR TELEPHONES
"
My invention consists in the construction of a carbon shell transmitter which is
useful for telephonic purposes. I make a carbon shell in two parts placed together
so as to form a hollow box but with an insulating material separating the two
portions and I attach conducting wires to each side of the shell. I put into the
shell granulated coke. The form of the shell or casing may be varied but I have
obtained good results with a spherical shell and also with a cylindrical shell having
flat ends.
By a modification of my invention the shell may be perforated care being taken
that the holes are not sufficiently large to allow the coke to escape; or any portion
of the shell may be replaced by perforated conducting material.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas Myddleton Morriss in the Patent Office on the 1st February
1884.
THOMAS MYDDELTON [sic] MORRISS, of 40 and 42 Queen Victoria Street, in the
city of London "IMPROVEMENTS IN TRANSMITTERS FOR TELEPHONES
"
My Invention consists in the construction of a carbon shell transmitter which is
useful for telephonic purposes. I make a carbon shell in two parts placed together
so as to form a hollow box but with an insulating material separating the two
portions and I attach conducting wires to each side of the shell. I put into the
shell granulated coke. The form of the shell or casing may be varied but I have
obtained good results with a spherical shell and also with a cylindrical shell having
Ant ends.
By a modification of my invention the shell may be perforated, care being taken
that the holes are not sufficiently large to allow the coke to escape; or any portion
of the shell may be replaced by perforated conducting material.
My object in devising this form of transmitter is, first, to employ grains of coke
as the active agent and, secondly, to speak to this mass direct, with as little
intervention as possible of any intermediate material substance.
It not being practicable to keep together the mass of coke particles without
something to hold them, I resort to porous carbon which allows the free passage of
the air waves through its substance and communicates the resulting vibrations to
the grains of coke much as if no casing were interposed. In order to make the
action of the air waves more direct, I perforate the carbon shell with minute holes
such as would be made by a sewing needle or very fine drill.
When I employ a perforated conducting material other than carbon I prefer to
use very fine wire gauze or similar material as one electrode. Any portion of the
shell may be replaced by perforated conducting material, the conductivity of which,
taken as a whole, approaches that of the enclosed coke particles.
In order to enable my invention to be fully understood I will proceed to describe
the same by reference to the accompanying drawing in which figures 1, and 2, are
sections showing the hollow spherical form of my improved transmitter, the shell
in figure 2, being shewn perforated; figure 3, is a longitudinal section and figure 4,
an end view shewing a solid cylindrical form of transmitter; figure 5, is a longi-
tudinal section shewing a hollow cylindrical form of transmitter; figures 6, and 7,
are a longitudinal section and an end view respectively shewing the short flat
cylindrical form of transmitter. Similar letters in all the figures are used to
represent similar or corresponding parts.
In the spherical form of transmitter shewn in figures 1, and 2, a, a, represent
the two halves of a sphere made of gas or other coke and forming the hollow shell,
that in figure 2, being shewn perforated; b, represents the insulating material
separating the hemispheres a, a,; c, c, are the terminal wires of the electrodes
and d, is the crushed coko placed within the shell a, a. In figure 2, I have shewn
both halves of the shell perforated with fine holes e, but it will be obvious that
only one of the balves may be so perforated, or the shell may be made without
perforations as shewn in figure 1.
Figure 3, shews a solid cylinder of coke a, with a hollow space for receiving the
crushed coke d; a, flat perforated end clearly shewn in figure 4; b, the insulating
material; c, c, the terminal wires; e, e, perforations.
The transmitter shewn in figure 5, is substantially the same as that shewn in
figures 3, and 4, except that the cylinder a, is hollow and therefore needs no further
description.

page_text: When the flat ends of the transmitters shewn in figures 3, 4, and 5, are made of
porous carbon or other suitable porous material the said ends do not require to be.
perforated.
In figures 6, and 7, a, shows a short flat cylinder of coke with an end of fine
wire gauze a',; in other respects it is similar to the transmitter shewn in figure 3.
The transmitter may be mounted in the usual way, and I find it convenient to
place some cotton wool in front of the instrument in order to absorb the moisture
of the breath.
Having thus described my invention and the manner of performing the same I
wish it to be understood that I do not confine myself to the precise forms of
transmitters herein before described and represented in the accompanying drawing
as it will be obvious that various other forms than those shewn may be employed
but what I do claim is
The manufacture and use of telephone transmitters constructed substantially as
herein before described and represented in the accompanying drawing.
In Witness whereof I the said Thomas Myddelton Morriss have hereto set my
hand and seal this first day of February in the year of our Lord one thousand eight
hundred and eighty four.
MODDING