IMPROVEMENTS IN TELEPHONIC APPARATUS
Year: 1883

page_text: LETTERS PATENT to John Graham of N° 33 Belmont Street Haverstock Hill
in the County of Middlesex Electrician for an Invention of IMPROVEMENTS
IN TELEPHONIC APPARATUS,
.7
PROVISIONAL SPECIFICATION left by the said John Graham at the Office
of the Commissioners of Patents on the 20th January, 1883.
JOHN GRAHAM of No. 33 Belmont Street Haverstock Hill in the County of
Middlesex Electrician IMPROVEMENTS IN TELEPHONIC APPARATUS,
The object of the invention is to afford increased facilities for the transmission
and receiving of telephonic communications by means of electric telephonic
apparatus with simplicity of construction and economy in manufacture of such
apparatus.
:
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For this purpose I provide in the case of apparatus to be used as a transmitting
instrument an interior soft iron or other suitable core surrounded by an insulated
winding of coarse wire, the two ends of this coarse wire coil being during, trans-
mission brought, in manner such as is..well, understood, into electrical connection
with a galvanic battery and removed from such connection when out of use. At
each extremity of this coil of coarse wire and around the ends of the interior, core,
is another coil of fine wire the inner extremity of this fine wire of each coil being
in electrical connection by wire or otherwise one with the other, and the outer
extremity of the one fine wire coil being connected to line and the other end of the
other to earth or loop as the case may be..
"
Opposite each end of the core is a suitable disc or diaphragm capable of being
vibrated and of thereby inducing pulsations of current in the coils of fine wire
which are transmitted in the usual manner'to a receiving instrument.
In the case of apparatus to be used as a receiving instrument the parts are
similarly constituted by an internal core of soft iron, or other suitable core,
surrounded by a coarse wire winding suitably insulated and similarly connected to
a galvanic battery as before described and of a fine wire coil at each end of the coil
of coarse wire, the inner end of each fine winding being electrically connected
together and their other fine wire ends being so connected one to line and the other
to earth or loop as the case may be.
.
In this receiving instrument the pulsations of current transmitted to the fine
wire coils cause those fine coils by their combined action greatly to increase the
attractivé power, of the core and cause the desired action upon the discs or
diaphragms which are provided opposite each end of such core in position to be
icted on thereby.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Graham in the Great Seal Patent Office on the 20th July
1883.
"
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JOHN GRAHAM of N° 33 Belmont Street Haverstock Hill in the County of
Middlesex Electrician "IMPROVEMENTS IN TELEPHONIC APPARATUS"
"
...The object of the invention is to afford increased facilities for the transmission
and receiving of telephonic communications by means of electric telephonic
apparatus with simplicity of construction and economy in manufacture of such
apparatus.
P
At
For this purpose I provide in the case of apparatus to be used as a transmitting 1
instrument an interior soft iron or other suitable core surrounded by an insulated
winding of coarse wire the two ends of this course wire coil being during trans-
mission brought in manner such as is well understood into electrical connection
with a galvanic battery and removed from such connection when out of use.
each extremity of this coil of coarse wire and around the ends of the interior core
is another coil of-fine wire the inner extremity of this fine wire of each coil being
in electrical connection by wire or otherwise ono with the other and the outer
extremity of the one fine wire coil being connected to line and the other end of the
other to earth or loop as the case may be.
Opposite each end of the core is a suitable disc or diaphragm capable of being
vibrated and of thereby inducing pulsations of current in the coils of fine wire
which are transmitted in the usual manner to a receiving instrument.
=
In the case of apparatus to be used as a receiving instrument the parts are
similarly constituted by an internal core of soft iron or other suitable core
surrounded by a coarse wire winding suitably insulated and similarly connected to
a galvanic battery as before described and of a fine wire coil at each end of the coil
of coarse wire the inner end of each fine wire winding being electrically connected
together and their other fine wire ends being so connected one to line and the other
to earth or loop as the case may be.
In this receiving instrument the pulsations of current transmitted to the fine
wire coils cause those fine wire coils by their combined action greatly to vary the
attraction of the core and cause the desired action upon the discs or diaphragms
which are provided opposite each end of such core in position..

page_text: of the coarse wire coil and one end of this single fine wire coil is connected to loop
or earth and the other to line-and two coarse wire coils taking the place of the
fine wire coils the inner ends of the coarse wire coils being connected together and
the outer ends thereof being joined to a local battery.
Having described the nature of my said invention and means for carrying into
practical effect I would have it understood that what I claim is :-
Forming electro telephonic apparatus with an inner core of soft iron or other
suitable material surrounded by inner and outer coils of fine and coarse wire,
connected electrically, arranged as and for the purpose substantially as described.
In witness whereof I the said John Graham have hereunto set my hand and
seal this Eighteenth day of July One thousand eight hundred and eighty three.
JOHN GRAHAM (L.S.)