IMPROVE- MENTS IN APPARATUS OR APPLIANCES FOR USE IN TELEPHONIC CIRCUITS
Year: 1882

page_text: LETTERS PATENT to John William Fletcher of 93 Chatham Street Stockport
in the County of Chester Telegraph Engineer for an Invention of IMPROVE-
MENTS IN APPARATUS OR APPLIANCES FOR USE IN TELEPHONIC CIRCUITS.
PROVISIONAL SPECIFICATION left by the said John William Fletcher at
the Office of the Commissioners of Patents on the 2nd August 1882.
JOHN WILLIAM FLETCHER, of 93, Chatham Street, Stockport, in the County of
Chester, Telegraph Engineer; IMPROVEMENTS IN APPARATUS OR APPLIANCES FOR
USE IN TELEPHONIC CIRCUITS
The objects of the invention are first, to provide simple apparatus easily applicable
to telephonic circuits whereby extraneous noises produced by induction and-
interfering with the proper reception of articulate sounds may be reduced and to a
great extent counteracted so as to make it possible to use a single wire and earth
whether the single wire is part of a cable or not, and second to provide an
improved switch or appliance for connecting or completing circuits at a telephone
exchange or otherwise where several telephone circuits are led to one centre.
The first part of my invention relates to apparatus or appliances in which there
is a primary coil which forms part of the telephone line wire circuit and an
induction coil which forms part of a receiving instrument circuit. Hitherto such
apparatus or appliances have been so constructed that the induction coil has been
affected both by induction from the primary coil and, from the core of the said
coil, thus preventing simultaneous action of the induced working currents
And the above first part consists in placing the primary and induction coils at a
distance from each other on an iron or iron wire core in such manner that the
currents of electricity in the line wire only act on the receiving instrument through
the currents induced by means of the core and not by direct induction from one
coil to the other.
In practice a battery and transmitting instrument are inserted in the line wire
or circuit; any number of receivers or coils may be connected to the one line wire
or circuit in either single or multiple circuit. The size and quantity of wire in
each coil is varied to suit circumstances.

page_text: Apart from this as an anti-induction arrangement my invention is an improve-
ment on the induction coil usually used inasmuch as the articulation is purer from
the fact that the induction is maguetic induction and not a combination of
magnetic and electrical induction.
Under the second part of my invention a switch whether consisting of a single
or double peg or connecting piece is joined to a local call circuit and battery.
When a single peg is used the said peg is made of two metal portions separated
from each other by insulating material. When the switch is in use the telephone
circuits are joined or completed through the local circuit connected to the peg or
pegs or equivalent switch.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John William Fletcher in the Great Seal Patent Office on the
2nd February 1883.
JOHN WILLIAM FLETCHER of 93 Chatham Street, Stockport, in the County of
Chester, Telegraph Engineer, IMPROVEMENTS IN APPARATUS OR APPLIANCES FOR
USE IN TELEPHONE CIRCUITS"
The objects of the invention are first, to provide simple apparatus, easily.
applicable to telephonic circuits whereby extraneous noises produced by induction
and interfering with the proper reception of articulate sounds may be reduced and
to a great extent counteracted so as to make it possible to use a single wire and
earth whether the single wire is part of a cable or not; and second, to provide an
improved switch or appliance for connecting or completing circuits to a telephone
exchange or otherwise where several telephonic circuits are led to one centre.
The first part of my invention relates to apparatus or appliances in which there
is a primary coil which forms part of the telephone line wire circuit and an
induction coil which forms part of a receiving instrument circuit. Hitherto such
apparatus or appliances have been so constructed that the induction coil has been
affected by induction from both the primary coil and the core of the said coil, thus
preventing simultaneous action of the induced working currents.
And the above first part consists in placing the primary and induction coils at a
distance from each other on an iron or iron wire core in such manner that the
currents of electricity in the line wire only act on the receiving instrument through
the currents induced by means of the core and not by direct induction from one
coil to the other.
In practice a battery and transmitting instrument are inserted in the line wire
or circuit any number of receivers or coils may be connected to the one line wire
or circuit in either single or multiple circuit. The size and quantity of wire in
each coil is varied to suit circumstances.
Apart from this as an anti-induction arrangement my invention is an improve-
ment on the induction coil usually used inasmuch as the articulation is purer from

page_text: the fact that the induction is magnetic induction and not a combination of magnetic
and electrical induction.
Under the second part of my invention a switch whether consisting of a single
or double peg or connecting piece is joined, to a local call circuit and battery.
When a single peg is used the said peg is made of two metal portions separated
from each other by insulating material. When the switch is in use the telephonic
circuits are joined or completed through the local circuit connected to the peg or
pega or equivalent switch.
DESCRIPTION OF THE DRAWINGS.
Fig 1 is a side elevation of apparatus or appliances illustrative of the first
part of my invention. a is a soft iron, or iron wire core, b is a coil of insulated,
primary or thick wire, c is a coil of insulated secondary induction or fine wire, two
coils surround the core a and are placed side by side some distance apart.
The wire of the coil b is connected to the main line circuit and the wire of the
coil c is connected to the telephone circuit. In practice a primary wire of 18 gauge
and secondary wire of 36 gauge are found to work well together; but the gauges
of the wires may be varied to suit circumstances say where great induction is to
be overcome wire of 16 gauge may be used whilst if the induction is small the
primary wire may be of 26 gauge; in both cases the secondary coil may remain
unchanged or even finer wire used. The above illustrated and described anti
induction apparatus may be arranged as shown in figs 2. 3. and 4, or it may be
fitted to any ordinary circuit say between the line wire and the line wire
terminal;
Two or more sets of coils may be used in combination. When the primary
and induction coils are on separate cores the said cores must be joined or connected
together.
Inasmuch as the primary coil is connected to the line wire and the secondary
coil is short circuited through the telephone there is no danger from the effects of
lightning either to apparatus, or to anyone using the telephone.
Figs 2 and 3 are elevations showing my improved anti-induction apparatus or
appliances arranged for use on a line of two stations only.
In fig 2 the line connections are shown in position for ringing the bell or calling
attention; in fig 3 the line connections are in position to allow of speech or
telephonic communication between the stations. D line wire, E earth connections,
F bell circuit, G anti induction coils, H battery, I switch, K telephone.
On reference to fig 2 it will be seen that by lifting either telephone at A or B
the switch I will be reversed and the bell of the other station placed in circuit and
sounded. When the second telephone is lifted both of the switches I will be
reversed and the line will be in a condition to allow of speech or telephonic
communication taking place.
<
Fig 4 is an elevation showing my improved anti-induction apparatus or
apparatus fitted to a line consisting of three stations. It will be observed that
the first and third stations are in position to allow of telephonic communication
and that the hammer of the bell at the second station is held up to the bell, which
indicates circuit is engaged; or to make the matter more clear a tablet marked
Engaged" actuated by the hammer stem may be used.
The same letters of reference as in figs 2 and 3 refer to equivalent parts. j is a
call switch for enabling any one station to sound the call bells.
I need not further particularize the system of connections between station and
station as many forms of such connections may be devised and they form no part
of my invention. The views 2, 3. and 4 are intended only to enable the method of
fitting and using my anti-induction apparatus to be better understood. Instead of,
or in combination with call bells, any desired form of indicator may be used.
Fig 5 is a side elevation, and fig 6 a plan of a switch peg for use where two

page_text: telephone circuits meet. The peg consists of two metallic parts L and M separated
from each other by insulating material N. P wires leading to a local circuit in
connection with an indicator. When three or more circuits are brought to the
same centre, the same description of peg is used but owing to the opposing currents
in part of the circuits, I insert a battery (Q) as shewn in Fig 7. This will obviate
the necessity of keeping batteries at terminal stations for speaking purposes. Bell
batteries only being required at those places.
The indicator may be of any usual or desired kind its object being to show when
the parties using the telephones have ceased communication.
Instead of a single split peg two pegs connected by wires to an indicator as
above described may be used:
Jiu
Having now described the nature of the said invention and particularized the
same, so that others will be enabled to carry my improvements, into effect
I claim.
L1J
First. The combination of a primary and secondary coil or coils and a core or
cores substantially as set forth.
Second Anti-induction apparatus or appliances constructed and operating
substantially as set forth under the first part.
Third. Telephonic switches constructed and connected substantially as set forth
under the second part.
In witness whereof I the said John William Fletcher have hereunto set my
hand and seal this thirty-first day of January in the year of our Lord
one thousand eight hundred, and eighty-three.
J JOHNSON
Patent Office
4 Clayton Sqr
Witness
}
JNO. WM. FLETCHER (L.S.)