Year: 1885

page_text: I, JOHNSTON STEPHEN of Ravelston Cottage, Blackhall, in the County of
Midlothian, Journalist, do hereby declare the nature of this Invention to be as
follows:-
The object of this Invention is to provide means for arranging a number of
telephone instruments so that they may all be served by one line. The line wire
euters each station where it passes around an electro-magnet which is so arranged
in relation to the poles of a magnet or magnets, (preferably two parallel horse-
shoe magnets,) that on a current being passed in one direction, the electro magnet
will move to one set of the poles, and on the current being sent in the opposite
direction, the electro magnet will move to the opposite set of poles.
The wire from the electro-magnet passes to a contact piece which moves with
the magnet and presses against one or the other of a pair of springs or their
equivalents so arranged that the motion of the electro-magnet which gives motion
to the said contact causes the said contact to make electrical contact with one
spring before leaving the other.
If the current, say a positive current, has been sent along the line, all the electro-
magnets at the different stations will have moved, say towards the left, and they
will remain there after the current has ceased to flow because the soft iron core of
the electro-magnet will stick to the poles of the permanent magnet towards which
they have been attracted and the current will now be through the left-hand spring.
Thence it will pass to the fulcrum of the Morse key, thence by the back stop to
the fulcrum of a telephone lever, such as is usually employed for hanging the
telephone upon, thence it will pass by the back stop of the said lever to the hinge
of a fall contact, thence by the back stop of the said fall contact to one terminal
of a coil, pivotted and placed in relation to a magnetic field or it may pass to a
fixed coil, in relation to which is a pivotted permanent magnet, thence it will pass
out again to the line.-The Morse key on being depressed will break contact at its
back stop and make contact with a terminal from one pole of a battery, the
opposite pole being put to earth. A current from the said battery will then pass
along the line to the switching station where it will indicate itself by ringing a
bell or otherwise.
If now the subscriber take his receiver off the hook, connection will be broken
at the back contact of the telephone lever, and contact will be made through
telephone receiver, and through the secondary coil in connection with the transmitter,
while another portion of the telephone lever, insulated from the first, will close a

page_text: circuit from a local battery, through the carbon transmitter, and the primary coil
in connection therewith. These are the steps required, when a subscriber wishes
to call the switching station and inform said switching station what connection
he requires. The duty of the switching attendant is now first to transmit such
currents along the line as will cause the pendulum at such subscribers station to
oscillate with amplitude when the fall contact will be released in the manner
described in the Specifications of my previous Patents Nos 3668 of 1884 and 15439
of 1884 when contact at the back stop of the said fall contact will be broken and
a new contact will be made first to the fulcrum of a part of the telephone lever
insulated from the other parts and thence by the back contact through the bell or
other annunciator-The back contact and the front contact for the fall contact
piece are so arranged that the one contact is not broken until the other one is made.
The fall contact piece also carries (but insulated from the part we have been
considering) a metallic piece connected by conducting material with the right hand
spring opposite to the metallic piece moved by the electro-magnet and which will
he in contact with the metallic piece if the electro magnet pass from the poles of
the permanent magnets (which hitherto have held it) to the other pair of poles
and also to a back contact and thence again to line. A metallic piece is connected
with this second portion of the fall contact and is connected to a metallic piece
opposite to the first portion of the fall contact.
If now the attendant at the switching station send a negative current along the
"wire it will happen that all the electro magnets along the line will pass to the right
.hand side and the current will now be in the case of those stations where the fall
contact is not down through the clectro magnet, through the metallic. piece con-
nected therewith through the right hand spring to the hinge of the second portion
of the fall contact through the back contact to line which will be seen to be a path
for the current which is not subject to being tapped or in any way drawn upon
nor accessible in any way save one and that is by the attendant at the switching
"station throwing down the fall contact of any particular subscriber when contact
is broken through the second portion of the fall contact at the back stop but
access is obtained by the first portion of the fall contact coming down upon
the metallic piece which I described as being opposite to it and metallically con-
nected to the hinge of the second portion of the fall contact and the current will
now pass through said metallic portion along the first portion of the fall contact
along the front contact to fulcrum of the telephone arm and thence through the
bell when the telephone is on the hook or when the telephone is off the hook
through telephone receiver and secondary coil of the transmitter.
Means for indicating whether the line be free or engaged and for replacing the
fall contact are provided and consist as follows-The movement of the electro-
magnet may move one or other of a pair of discs on which the word "free" and
"engaged" are respectively placed and bring one or other of such discs opposite a
window, that is to say when the electro magnet is on the left hand side the word
"free" will be shewn and when it is on the right hand side the word ". engaged
will be shown.
"
The movement of the electro magnet also actuates a wheel and axle and each
movement of the electro magnet from right to left will work round the wheel
through one definite distance-The wheel has cogs or teeth the movement of
which through a definite distance tilts a lever in passing it which lever at its other
end resets the fall contact behind its detent or catch.
.

page_text: I JOHNSTON STEPHEN of Ravelston Cottage Blackhall in the County of Mid-
lothian Journalist 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 :-
The object of this Invention is to provide improved means for arranging a
number of telephone instruments so that they may all be served by one line. The
line wire enters each instrument where it passes round an electro magnet which is
so arranged in relation to the poles of a magnet or magnets (preferably two parallel
horse shoe magnets) that on a current being passed in one direction the electro
magnet will move to one set of the poles and on the current being sent in the
opposite direction the electro magnet will move to the opposite set of poles.
The wire from the electro-magnet passes to a frame or contact piece which moves
with the magnet and presses against one or the other of a pair of springs or their
equivalents so arranged that the motion of the electro magnet which gives motion.
to the said frame or contact causes the said frame to make electrical contact with
one spring before leaving the other.
If the current say a positive current has been sent along the line all the electro
magnets at the different stations will have moved say towards the right and they
will remain there after the current has ceased to flow because the soft iron core of
the electro magnet will stick to the poles of the permanent magnet towards which
they have been attached and the current will now be through the left hand spring.:
Thence it will pass to the fulcrum of a Morse key or contact maker thence by the
back stop of the said Morse key to the fulcrum of a telephone lever such as is.
usually employed for hanging the telephone upon thence it will pass by the back
stop of the said lever to the binge of a fall contact thence by the back stop of the
said fall contact to one terminal of a coil pivotted and placed in relation to a
magnetic field or it may pass to a fixed coil in relation to which is a pivotted
permanent magnet it will then pass out again to the line. The Morse key on
being depressed will break contact at its back stop and make contact with its front:
stop connected to a terminal from one pole of a battery (the negative pole for.
example) the opposite pole being put to earth. A current from the said battery
will then pass along the line to the switching station where it will indicate itself
by ringing a bell or otherwise. If now the subscriber take his receiver, off the
hook, connection will be broken at the back contact of the telephone lever and
contact will be made through telephone receiver and through the secondary coil in
connection with the transmitter, while another portion of the telephone lever
insulated from the first will close a circuit from a local battery through the carbon
transmitter and the primary coil in connection therewith. These are the steps
required when a subscriber wishes to call the switching station and inform the
switching station what connection he requires. The duty of the switching
attendant is now first to transmit such currents (positive for example) along the
lines as will cause the pendulum at such subscribers station to oscillate with

page_text: amplitude when the fall contact will be released in the manner described in the
Specifications of my previous Patents Nos 3668% and 15439. Contact at the
back stop of the said fall contact will be then broken and a new contact will be
made to the terminal of the relay and through the said relay to the line. The
back contact and the front contact for the fall contact piece are so arranged that
the one contact is not broken until the other one is made. The fall contact also
carries (but insulated from the part before referred to) a metallic piece, connected
by conducting material with the right hand spring opposite to the metallic frame
moved by the electro magnet, and which will be in contact with the metallic piece
if the electro magnet pass from the poles of the permanent magnets (which
hitherto have held it) to the other pair of poles and also to a back contact and
thence again to line.
If now the attendant at the switching station send a negative current along the
wire it will happen that all the electro magnets along the line will pass to the left
hand side and the current will now be, in the case of those stations where the fall
contact is not down, through the electro magnet, through the metallic piece or
frame connected therewith through the right hand spring to the hinge of the
second portion of the fall contact, and through the back contact to line-This will
be seen to be a path for the current which is not subject to being tapped or in any
way drawn upon nor accessible in any way save one, and that is by the attendant
at the switching station throwing down the fall contact of any particular sub-
scriber, when contact is broken through this second portion of the fall contact at
the back stop but access is obtained by the fall contact coming down upon the
metallic piece which is opposite to it and metallically connected to the fulcrum of
the Morse key and the current will now pass through said metallic portion to the
fulcrum of the Morse key thence by the back stop thereof to the fulcrum of the
telephone arm and thence through the relay (which closes a local current through
the bell) when the telephone is on the hook or when the telephone is off the hook
through telephone receiver and secondary coil of the transmitter.
Means for indicating whether the line be free or engaged and for replacing the
fall contact are provided and consist as follows.
The movement of the electro magnet may move one or other of a pair of discs
on which the word "free" and "engaged" are respectively placed and bring one or
other of such discs opposite a window, that is to say when the electro magnet is on
the right hand side the word "free" will be shewn and when it is on the left hand
side the word "engaged" will be shewn. Or one disc only may be employed
which is brought opposite a space in the front of the instrument to indicate the
line inaccessible and removed therefrom when the line is free or accessible.
The movement of the electro magnet may also move forward or backward one of
two hooked levers which maintain the fall contact upright or in its backward
position The backward movement of this lever will replace the fall contact and
cause it to engage with the hook of another lever which has no backward and
forward motion and which will retain the fall contact in its backward position
and allow the other hooked lever to work to and fro without acting upon the fall
contact.
And in order that my said Invention may be fully understood I shall now
proceed more part cularly to describe the same and for that purpose shall refer to
the several figures on the annexed sheets of drawings the same letters of reference
indicating corresponding parts in all the figures.
Figure 1 is a front elevation of a subscribers' telephonic instrument constructed
according to my invention to be employed in my improved telephone system and
the remaining Figures are diagrams illustrating the course of the currents and
the different positions. which the parts of the instrument assume under various
circumstances.
The instrument shewn in Figure 1 is intended to be attached to or suspended
against a wall and consists of a box or case A preferably having a glass panel door
or front B through which the contents of the box or case may be viewed.

page_text: In the interior of this box is an electro magnet C mounted in a frame C² capable
of movement between the poles of two horse shoe permanent-magnets D the front
one only being shown in my drawings-The frame C' is provided at its upper end
with a disc E for indicating as hereinafter described when the line is inaccessible
and when it is free-The frame C² also carries a contact piece which according
as the line-is free or engaged and the electro magnet is accordingly to the right or
left, switches the line on to one or other of the spring contacts R or R2 and thence
to the accessible or inaccessible portion of the line. F and F (fig. 4) are hooked
levers for returning to and retaining the fall contact piece H in its backward or
vertical position. K-is a Morse key or contact maker for signalling the exchange
attendant when a subscriber desires to be placed in communication with another
subscriber, and also for signalling that conversation is over. I is a relay for closing
a local circuit through local bell (not shown) and L an oscillatory pendulum capable
of being actuated from the exchange by a succession of currents synchronous
with its period. When actuated it swings with amplitude and by striking_up
the hooks F F1 releases the fall contact H. M is the transmitter and N a Bell
receiver.- are binding screws for connecting the terminals of a shunt resistance
which may be employed to modify the effect of the line current upon the coil L*
of the oscillatory pendulum L should the current be too strong-For example if it
be required to reduce the strength of the current in the pendulum coil one half ȧ
resistance shunt equal to the coil L³ is connected to the binding screws O. If it be
required to reduce the strength to one third a resistence shunt equal to two thirds
of the coil is connected, and so on. By this means whatever may be the strength of
the line current the effect thereof in the coil L³ may be regulated as desired. The
several parts of the apparatus are represented in Figure 1 and diagrammatically in
Figure 2 in their normal position the line being open or accessible for the trans-
mission of messages. The line wire P leading from the exchange Q enters the
box A and passing thence round the electro magnet C is attached to the frame C¹
which is moveable with the electro-magnet C the frame C¹ being centred at y.
The line P¹ connecting the instrument of one subscriber with that of the next
subscriber in the system is connected with the pendulum coil L-The upper part
of the frame C₁ when in its normal position as shewn in Figures 1 and 2 presses
against the spring contact R the said frame being maintained in this position by
the attraction of the permanent magnets D. A current from the exchange Q
passing through the line P enters the electro magnet C and passes thence through
the frame Cand spring contact R to the hinge S of the Morse key or contact
maker K (see Figure 2) thence through the back contact piece U to the hinge V
of the lever W upon which the receiver N is suspended, thence through the back
contact piece X.to the hinge T of the fall contact H and contact piece Y to the
coil L² of the oscillatory pendulum L and thence to the line P¹ leading to the next
subscribers instrument and in like manner through his instrument to the next
subscribers instrument and so on throughout the system till finally the line goes
'to earth.
When a subscriber wishes to communicate with another subscriber he calls up
the exchange attendant by depressing the Morse key or contact maker K thereby
breaking contact with the piece U and making contact at a with one pole (the
negative in the case illustrated) of a local battery b-A current from the battery b
will then pass through the fulcrums of the Morse key K to the spring contact R
thence through the frame C¹ and the electro magnet Ċ and through the line P to
the bell or other annunciator at the exchange Q The subscriber then removes his
receiver from the lever W and informs the exchange attendant bis requirements
and then replaces his receiver The exchange attendant now sends a current to
release the contact maker H causing it to assume the position shewn in figure 3
when the current will traverse the relay I and ring the subscribers bell. The
subscriber then rings back, whereupon the exchange attendant sends a reverse
current through the line thereby locking out all the subscribers except those who
desire to be put into communication.

page_text: The subscriber now removes his receiver from the lever W thereby making a
contact between an insulated portion c of the lever W to which insulated portion
is connected one terminal of the transmitter battery and one terminal a³ of a
primary coil din series with the transınitter M and the other pole of the transmitter
battery At the same time the other portion of the lever W makes contact with
one terminal of the secondary coil e which is in series with the receiver N and with
the exit terminal of the line at P¹ (figure 2).
The conversation may now go on for any length of time and without fear of
interruption or overhearing-When it is over one or both of the subscribers ring
off, and the exchange attendant may be apprized by the fall of his annunciator that
conversation is over and that the line may be cleared-He now depresses the key
that sends a positive current along the line when all the electro magnets will
again pass to right-The indicators will show that the line is again accessible and
the fall contacts that are down will be replaced.
L³ (figure 1) is an arm attached to the pendulum L for striking up or raising the
hooked levers F F¹ for releasing the contact maker H which when released will
fall over into the position shewn in Figures 3 and 4 breaking its contact with the
piece Y and making contact with the piece h of the relay I The striker L³ only
acts when the Exchange Clerk shall have set his Metronome opposite the fiducial
number of subscriber.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
First In a telephone system in which a number of telephone instruments are
served by one line providing each instrument with an oscillatory electro magnet
round which or in proximity to which the line wire passes, the said magnets being
caused to pass to one or other of the pairs of poles of permanent magnets according
as the current transmitted through the line be a positive or a negative current and
whereby the line may be rendered either accessible or non-accessible as required
substantially as herein before described and illustrated by my drawings.
Second The combination with the oscillatory electro magnet C and frame C¹
fitted to pass between the poles of permanent magnets and carrying a disc or
indicator E, of the contacts R R and H contact pieces Y and h relay 1 oscillating
pendulum L and coil L³ the whole being arranged substantially as and for the
purpose herein before described and illustrated by my drawings.
Third-The combination with the permanent magnet or magnets D and
oscillating electro magnet C and frame C₁ of the resetting arrangements illustrated
in Figures 4, 7, 8 and 9 the whole being arranged to operate substantially in the
manner and for the purpose herein before described and illustrated by my drawings.
Fourth-The combination with a permanent magnet or magnets D of an
oscillatory electro magnet C, frame C₁, contact piece K, Morse key or contact
maker K, and local battery b, the whole being arranged substantially as and for
the purpose herein before described and illustrated by my drawings.
-
Fifth The general combination and arrangement of parts constituting the
telephone instrument hereinbefore described and illustrated by my drawings.
Dated the seventh day of August 1886.