IMPROVEMENTS IN AND CONNECTED WITH TELEPHONIC APPARATUS."
Year: 1881

page_text: LETTERS PATENT to Julius Sax, of Great Russell Street, in the County of
Middlesex, for an Invention of "IMPROVEMENTS IN AND CONNECTED WITH
TELEPHONIC APPARATUS."
PROVISIONAL SPECIFICATION left by the said Julius Sax at the Office of
the Commissioners of Patents on the 8th February 1881.
JULIUS SAX, of Great Russell Street, in the County of Middlesex. " IMPROVE-
MENTS IN .AND CONNECTED WITH TELEPHONIC APPARATUS."
My Invention relates to that description of telephone or telephonic apparatus in
which an electro magnet and battery are employed, and in which a microphone is
used in combination with a telephone, and the Invention has reference to the mode
of constructing the electro magnet, and of connecting up the same, whereby a single
battery is caused to serve both for the telephone and the microphone, such battery
being augmented to any required strength.
In carrying out my Invention I construct the electro magnet with two distinct
wires, a portion, say, about two thirds of each pole, being coiled with wire of a low
resistance (jointly 8 ohms.), whilst the remainder (say, one third) of each pole is
coiled with wire of a high resistance (jointly 80 ohms.), and I fit the magnet in a
case with an iron diaphragm, and connect it up with the microphone, an induction
coil, and battery in the following manner :-
The carbon pole of the battery is connected to a spring, the zinc pole being in
connection with the one side of the microphone and one wire of the low
resistance coil. The second wire of the low resistance coil is connected to another.
spring, which is also connected to one end of the primary wire on the induction
coil. The second end of the primary wire is connected to the second side of the.
microphone. The one end of the high resistance coil is connected to line, the other
end being in connection with one end of the secondary wire on the induction
coil, whilst the second end of the secondary wire is joined to earth.
The resistance of the low resistance coils should be as nearly as possible equal
to the primary wire of the induction coil and the microphone together, the
advantage of this and the result of the arrangement hereinbefore described being
that when the two springs are pressed together, the current from the battery.
divides itself, one half flowing through the primary wire and microphone, and the
other half flowing through the low resistance coils, so that the same battery which
supplies the microphone charges the electro magnet of the telephone.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Julius Sax in the Great Seal Patent Office on the 26th July 1881.
JULIUS SAX, of Great Russell Street, in the County of Middlesex.
MENTS IN AND CONNECTED WITH TELEPHONIC APPARATUS."
"IMPROVE-
My said Invention relates to that description of telephonic apparatus in which
an electro magnetic receiving telephone, or telephone proper, and a battery are
employed, and in which a microphone is used in combination with such telephone,
and my Invention has reference to the mode of constructing the electro-magnet of
the telephone, and of connecting up the same, whereby a single battery is caused to
serve both for the telephone and the microphone, such battery being augmented to
any required strength.
In carrying out my said Invention the electro magnet of the telephone is enclosed
in a casing provided with a vibrating iron diaphragm, as heretofore; but in lieu of
using a single wire I construct the electro-magnet with two distinct wires, a portion
(say, about two thirds) of each pole being coiled with wire of a low resistance,
whilst the remainder (say, one third) of each pole is coiled with a wire of a high
resistance; or as an equivalent arrangement I may apply the wire of high resistance
to an extension of one only of the poles of the electro-magnet, whilst the other
portion of the pole so extended and the opposite pole are coiled with wire of a low
resistance. The continuations of the wires of the electro-magnet so constructed are
then connected with a microphone induction coil and battery, in such a manner
that providing the resistance of the low resistance coils have been made as nearly
as possible equal to the primary wire of the induction coil and the microphone
together; the current from the battery will divide itself; one half flowing through
the primary wire and microphone, and the other half flowing through the low
resistance coils, so that the same battery which supplies the microphone charges
the electro magnet of the telephone.
And in order that my said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the annexed Sheet of Drawings, the same letters of reference
indicating corresponding parts in all the Figures.
Figure 1 of the accompanying Drawings represents a vertical section of an
electro-magnetic receiving telephone with my improved construction of electro-
magnet applied thereto, the microphonic transmitter induction coils, contacts, and
usual appurtenances being diagrammatically shewn in connection therewith.
Figure 2 is a plan of the electro-magnetic receiving telephone with the cap or
top cover and metallic vibratory diaphragm removed in order to show the electro
magnets.
Figure 3 is a vertical: section of a similar electro-magnetic receiving telephone
with an electro-magnet constructed according to a modification of the arrangement
shewn in Figures 1 and 2, and Figure 4 is a plan of the said telephone with the
top or cover of the apparatus removed.
A is an electro-magnetic receiving telephone consisting of a casing containing a
diaphragm D, on one side of which is a mouth-piece A¹, whilst on the opposite
side of the diaphragm within the casing is an electro-magnet, the general arrange-
ment of the parts being such as is commonly adopted in apparatus of this
character. According to my said Invention in lieu of using a single wire I
construct the electro-magnet with two distinct wires wound upon the polar
cores B, B¹, so as to form two separate sets of wire coils of differential resistance.
One set of these wire coils (marked respectively L, L',) which cover, say, about
two thirds the length of the polar cores B, B¹, are of low resistance equal to, say,
about 8 ohms. jointly, and the other set of wire coils (marked respectively H, H',)
which surround the remaining third of the polar cores B, B¹, are composed of a

page_text: second and separate wire of high resistance, equivalent jointly to, say, about
80 ohms.
The continuations of the wires from the two sets of coils are connected with a
microphone M (which may be of any suitable construction), an induction coil I, and
a battery C, in the following manner: —
The carbon pole C of the battery C¹ is connected to the spring c, whilst the
zine pole Z is connected by means of the wire z to one side of the microphone M,
and also by a branch wire to the one termination of the low resistance coil Ļ
upon the pole B of the electro-magnet of the receiving instrument. The other end
of the wire forming the second portion of the low resistance coil L' on pole B¹ is
attached to wire in connection with another spring contact p², and also with the
branch wire p communicating with the primary wire and belix P of the induction
coil I, the other end of which primary wire is similarly connected to the other
side of the microphonic transmitter M by the wire p¹. One end of the high
resistance coil from H is connected to "line" by means of the wire h, whilst its
other extremity from H¹ is connected by the wire h' to the secondary wire and
helix S of the induction coil I, by which it communicates with "earth" by the
wire 8.
The resistance of the low resistance coils should be as nearly as possible equal
to that of the primary wire of the induction coil and the microphone together.
Under these conditions by the act of pressing the spring contacts c or p² so as to
unite their free extremities the current from the battery C is caused to divide
itself owing to the uniformity of resistance so as to flow partly through the
microphone and partly through the differential resistance coil so as to charge or
influence the electro-magnet of the receiving telephone, whereby one battery is
made to serve for both instruments, the strength of the battery being augmented
as required.
As an equivalent to the arrangement herein before described with reference to
Figures 1 and 2, I may modify the construction of the electro-magnet in the
manner illustrated in Figures 3 and 4 by making one polar core of the electro-
magnet longer than the other, as shewn at B', and winding upon its extended
portion the wire of the high resistance coil H instead of the said wire covering both
poles, as hereinbefore described with reference to the previous arrangement. The
arrangement of the low resistance coils remains unaltered, and the requisito
connections with the microphone induction coil and battery are likewise effected
in a similar manner to those of the arrangement first herein before described.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,-
In telephonic apparatus of the description hereinbefore referred to, constructing
the electro-magnet of the telephone with two distinct wires of suitably proportioned
resistance, and arranged and connected with a battery, a microphone, and appur-
tenances in such a manner that the battery current is divided, whereby one and
the same battery is made to serve for both the telephone and microphone,
substantially as herein before described.
In witness whereof, I, the said Julius Sax, have to this my Specification
set my hand and seal, this 22nd day of July, One thousand eight
hundred and eighty one.