Improvements in and connected with Telephones.
Year: 1892

page_text: Date of Application, 23rd Mar., 1892
Complete Specification Left, 22nd Dec., 1892-Accepted, 18th Mar., 1893
PROVISIONAL SPECIFICATION.
Improvements in and connected with Telephones.
We, GEORGE LEE ANDERS of 33 Peak Hill Gardens, Sydenham in the County
of Kent, Electrician, and WALTHER KÖTTGEN of 10 Jeffreys Square in the City
of London, Merchant do hereby declare the nature of this invention to be as
follows:-
In making the carbon contact in telephonic and microphonic instruments
considerable difficulty has been found in getting a carbon which, while having a
certain amount of flexibility will not break or chip.
According to the present invention it is proposed to incorporate with the carbon
prior to placing the same in the retort, wire mesh or perforated sheet metal, into
the interstices of which the carbou will enter and thereby be securely held.
Instead of the wire inesh one or more wires or strips may be employed. The face
of the carbon where contact is to be made may be formed of cotton or like fibre
which when carbonized will give a flexible conductive surface.
It will be evident that the metal or wire mesh employed must be of such a
character as to stand the heat of the retort.
Dated this 23rd day of March 1892.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in and connected with Telephones.
We, GEORGE LEE ANDERS of 33 Peak Hill Gardens Sydenham in the County
of Kent Electrician, and WALTHER KÖTTGEN of 10 Jeffreys Square in the City
of London, Merchant, 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 :—
In making the carbon contact in telephonic and microphonic instruments
considerable difficulty has been found in getting a carbon which, while having a
certain amount of flexibility will not break or chip.
According to the present invention it is proposed to incorporate with the carbon
prior to placing the same in the retort, wire mesh or perforated sheet metal, into
the interstices of which the carbon will enter and thereby be securely held.
Instead of the wire mesh one or more wires or strips may be employed. The face
of the carbon where contact is to be made may be formed of cotton or like fibre
which when carbonized will give a flexible conductive surface.
It will be evident that the metal or wire mesh employed must be of such a
character as to stand the heat of the retort.
We judge the following will be the most advantageous way of carrying our
invention into effect. We take a suitable piece of wire gauze or thin perforated
sheet metal and cover or coat one or both sides of same with carbon in a plastic
condition or with material capable of becoming carbonized when submitted to a
proper temperature. We prefer that the material should be forced into the inter-
stices under pressure in a suitable mould. At that point of the diaphragm where
it is intended that microphonic action shall take place we prefer to have a specially
prepared carbon such as carbonized fibre of suitable conductivity and consistency
to give the desired microphonic effect.

page_text: The metal at this point of the diaphragm may be recessed, shaped or moulded by
pressure or otherwise so as to render it capable of receiving and holding the desired
quantity of carbon.
The diaphragm thus made is dried or baked in a retort in the usual manner after
which if desired it may be steeped in a suitable bath and rebaked so as to improve
its density and conductivity or a carbon or other vapor may be introduced into the
retort during the baking period.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. In telephonic apparatus a diaphragm of combined metal and carbon substan-
tially as set forth.
2. In telephonic apparatus a diaphragm having at that point where microphonic
action is to take place a special form of carbon for contact, substantially as set
forth.
Dated this 22nd day of December 1802
PHILIP M. JUSTICE, Fel. Chart. Inste. P.A.,
55 & 56, Chancery Lane, London, Agent for the Applicants.