Improvements in and relating to Apparatus for the Transmission and Reproduction of Sounds.
Year: 1891

page_text: Date of Application, 30th Oct., 1891
Complete Specification Left, 2nd Aug., 1892-Accepted, 1st Oct., 1892
PROVISIONAL SPECIFICATION.
Improvements in and relating to Apparatus for the Transmission
and Reproduction of Sounds.
I, THOMAS JAMES HOWELL, of 28, Ferndale Road, Forest Gate, in the
County of Essex, Engineer do hereby declare the nature of this invention to be
as follows:-
My invention relates to acoustic telegraphs or telephones, that is to say, to
apparatus for the transmission and reproduction of sounds, and the said invention
is designed to facilitate the carrying on of conversation through insulated wires or
conductors, by increasing the articulation and volume of the reproduced sounds.
The chief object of my said invention is to provide an improved instrument
which will serve very efficiently both as a microphone or transmitter and as a
receiver.
For this purpose I make a combined microphone and electro-magnetic
telephone.
I construct my electro-magnetic telephone with magnetised pieces of steel which
extend across the case of the instrument and which are bent so that their ends are
in proximity to the diaphragm or tympan; the said magnetised pieces are securely
held in place by a bolt of soft iron, upon which is placed an ordinary coil of
insulated wire, thus forming an electro-magnet: These magnetised pieces of steel
considerably increase the effectiveness of the instrument as an electro-magnetic
telephone.
To produce a combined microphone and electro-magnetic telephone, I find it
advantageous to proceed' as follows, that is to say, I place one or more carbon
plates or discs in the back of the case of the instrument behind or between the
magnetised pieces of steel, and secure them in place in any convenient manner, for
instance by, means of the aforesaid bolt. I then fill up the space within the case
and around the electro-magnet with powered or granulated carbon. Carbon made
from wood, sugar or other suitable substances may be used for this purpose; it is
preferable, however, to employ coke, or "scurf" from gas-retorts. On the top or
in front of the granulated carbon, I place another carbon plate or disc which is
kept in contact with the granulated carbon. The back or inner carbon plate is
connected with one of the leading-in wires. The other wire is connected with one
end of the coil, the other end of which is connected with the front or outer carbon
plate, preferably through the medium of a ring or annular piece of copper or other
suitable metal in contact with the said plate. It will, therefore, be seen that a
microphone is produced, the electric circuit being completed through the powdered
or granulated carbon. The loudness and articulation of the sounds are thus
greatly increased, and the apparatus is adapted for use both as a microphone and
as a receiver.
The diaphragm or tympan is preferably arranged in front of the outer carbon
plate.
Instead of the carbon plates or discs, I can, if desired, use plates or discs of
metal, though with less advantage. Moreover I can, if desired, substitute for the
front or outer carbon plate, a thin piece or disc of mica, paper or other suitable
material to retain in place the powdered or granulated carbon. In this case, the
electric circuit is completed from the aforesaid metal ring through the granulated
carbon to the back or inner carbon plate or plates. Furthermore, the granulated
carbon may, if desired, be replaced by other materials suitable for the purpose.
The box or case of the instrument may be of ebonite, wood or other suitable
insulating, material, or it may, be of metal properly, insulated. It is provided with
T

page_text: an ear-piece or mouth-piece of any convenient form. The said box or case may,
moreover, be of circular, square, oblong or other suitable shape as may be found
in practice most desirable.
Dated this 30th day of October 1891.
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in and relating to Apparatus for the Transmission
and Reproduction of Sounds.
I THOMAS JAMES HOWELL of 28 Ferndale Road, Forest Gate, Essex,
Engineer do hereby declare the nature of this invention 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 acoustic telegraphs or telephones, that is to say, to
apparatus for the transmission and reproduction of sounds and the said invention
is designed to facilitate the carrying on of conversation through insulated wires
or conductors, by increasing the articulation and volume of the reproduced
sounds.
The chief object of my said invention is to provide an improved instrument
which will serve very efficiently both as a microphone or transmitter and as a
receiver.
For this purpose I make a combined microphone and electro-magnetic telephone
of the following construction:
I construct my electro-magnetic telephone with four or any number of magnetised
pieces of steel which extend across the back of the instrument either inside or
outside, and which are bent so that their ends are in proximity to the diaphragm
or tympan, and the said magnetised pieces are securely held in place by a bolt of
soft iron, upon which is placed an ordinary coil of insulated wire. These mag-
netised pieces of steel considerably increase the effectiveness of the instrument as
an electro-magnetic telephone.
To produce a combined microphone and electro-magnetic telephone, I find it
advantageous to proceed as follows, that is to say, I place two plates or pieces of
carbon in the back of the case of the instrument between the magnetised pieces of
steel and secure them in place in any convenient manner, for instance by means
of the aforesaid bolt or by screws. I then fill up the space within the case and
around the bolt and coil, with powdered or granulated carbon or graphite. Upon
the top or in front of the granulated carbon or graphite, I place another plate or
piece of carbon, which is kept in contact with the granulated carbon or graphite.
The two plates or pieces of carbon or graphite are connected with one of the
leading in wires. The other leading-in wire is connected with one end of the coil,
the other end of which is connected with the front or top plate or piece of carbon,
preferably by means of a ring or annular piece of copper or other suitable metal
in contact with the said plate. It will, therefore, be seen that a microphone is
produced, the electric-circuit being completed through the powdered or granulated
carbon. The loudness and articulation of the sounds are thus greatly increased
and the apparatus is adapted for use both as a microphone transmitter and receiver
combined.
The diaphragm or tympan is arranged in front of the top carbon plate.
Instead
of the plates or pieces of carbon or graphite, I can, if desired, use plates or pieces
of metal. Furthermore, the granulated carbon may be replaced by any other
suitable material.
The box or case of the instrument may be of ebonite, wood or other suitable
insulating material, or it may be of metal properly insulated. It may be of circular,

page_text: square, oblong, or any other suitable shape, and provided with an ear-piece or
mouth-piece of any convenient form.
The advantages of this arrangement are-that a transmitter, microphone and
receiver are combined in one and the same instrument which may be used either
with or without a battery and that the loudness and articulation of speech or
sounds are both greatly increased when a galvanic battery is brought into
circuit.
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 apparatus for the transmission and reproduction of sounds the combination
in one and the same instrument of transmitter, microphone and receiver substantially
as hereinbefore described.
2. In apparatus for the transmission and reproduction of sounds the combination
of plates or pieces of carbon, graphite or metal with a number of pieces of
magnetised steel extending across the instrument and bent so that their ends may
be in proximity to the diaphragm or tympan and held in position by a bolt of soft
iron on which is an ordinary coil of insulated wire, the whole being surrounded
and separated by and the case filled up with powdered or granulated carbon or its
equivalent confined by means of another plate or piece of carbon substantially as
described.
3. The apparatus for transmission and reproduction of sounds substantially as
hereinbefore described.
Dated this and
1000
POPPLEWELL & Co.,
17 & 18, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.