IMPROVEMENTS IN TELEPHONE OR TELEGRAPH CALL APPARATUS AND " CIRCUIT ARRANGEMENTS
Year: 1883

page_text: LETTERS PATENT to Henry Alfred Charles Saunders and Alfred Charles
Brown both of 66 Old Broad Street in the City of London for an Invention
of IMPROVEMENTS IN TELEPHONE OR TELEGRAPH CALL APPARATUS AND
"
CIRCUIT ARRANGEMENTS
"
PROVISIONAL SPECIFICATION left by the said Henry Alfred Charles.
Saunders and Alfred Charles Brown at the Office of the Commissioners of
Patents on the 20th April 1883.
- HENRY ALFRED CHARLES SAUNDERS and ALFRED CHARLES BROWN both of
66 Old Broad Street in the City of London. " IMPROVEMENTS IN TELEPHONE
OR TELEGRAPH CALL APPARATUS AND CIRCUIT ARRANGEMENTS
4
"
The object of this invention is to enable an operator stationed at any one
telegraph or telephone station of a number of such stations in series on one line
wire to sound an alarm or make any other suitable call at any other one of the
said stations without disturbing the remainder.
This is accomplished by taking advantage of that property of pendulums (by
which when the propelling impulses are small) they will only oscillate continuously
in response to impulses given at their own proper rate of oscillation but will
periodically interfere and come to rest again when subjected to impulses given at
any other rate.
Reed vibrators which have long been used for similar purposes but in applying
them to telephonic signalling a difficulty occurs in consequence of variations in the
currents. These variations arise in practice from a number of causes but chiefly on
telephone circuits from the variation of the resistance of the circuit when the line
is successively plugged through to a number of different lines. Then either the
weaker currents fail to accumulate sufficiently ample oscillation in the reed vibrator
or else the stronger currents exercise too much control over the reed and bring it
into operation when the next numbers are being called. More especially is this the
case when the currents used are those produced by the magneto machines used in

page_text: telephonic work. These currents being undulatory in their nature and being
subject to external variations from variations of speed in turning.
From the above mentioned and other causes reed vibrators are thrown into
vibration even when the rate of succession of currents is made very considerably
different to the proper rate of the reed. Our invention however enables these
magneto machines together with their own ordinary alarm bells to be used. We
employ slower moving and more certainly isochronous gravity pendulum.
At each station of a number in series on one line we place a pair of pendulums
supended in any ordinary manner one for transmitting and the other for receiving.
The transmitting pendulum is actuated by a single impulse given to it by hand by
the operator in calling. It carries a moveable bob capable of being placed in any
position by the operator the proper positions for each station to be called being
denoted either by notches cut in the pendulum rod or by a graduated scale placed
behind. This pendulum operates to make and break electrical contacts by lifting
a light contact spring off a contact screw once for each oscillation or by oscillating
between two adjustable contact points placed a short distance below the point of
suspension. The relative duration of make to break is adjustable by turning the
contact screw out or in. Or the electrical contact may be made by the pendulum
rod itself coming into contact with a wire projecting from a spring.
The receiving pendulums are actuated by the current by means of an electro-
magnet at each station whose coils are in series in the line circuit. They each
carry a bob which is placed at a different position at each station on the line
(corresponding to one of the divisions on the scale for transmitting pendulums at
every station). When therefor the bob of a transmitting pendulum is placed at any
particular height and the pendulum started currents from any source are caused to
flow through the contacts which it actuates and along the line, only that receiving
pendulum whose bob is set to cause it to make that particular number of oscilla-
tions per second will respond and accumulate a considerable arc of oscillation. The
others will simply after making a few small oscillations interfere and come to rest
again. The receiving pendulum which accumulates the oscillations knocks against
a piece of wire projecting from a light contact spring and lifts the said spring off
a screw stud with which it normally makes contact. This contact when made
closes a short circuit around the coils of the bell or call signal which is in series in
the line circuit and since this contact is broken by the receiving pendulum at a
time when by the operation of the transmitting pendulum a current is on the line
the call will sound at each oscillation. Or the pendulum rod may be made to open
and close local circuits.
In order that the pendulum may be influenced equally or nearly so by strong
and by weak currents instead of attaching the armature to the pendulum rod and
allowing the electro magnet to attract the pendulum directly we suspend the
armature by a fairly stout spring and we then suspend the pendulum rod proper to
the bottom of the armature either by a thin flexible blade or spring or knife edges.
At the back of the armature there is an adjusting screw by which its play can be
limited to as small an extent as desired. Now since the armature is by this means
always kept very close to the electro magnet the weakest current capable of
working the apparatus at all (and much weaker than any likely to be experienced)
will pull the armature right up while the strongest possible current can do no
more; the surplus energy simply spending itself on the poles of the magnet. The
armature attaching spring also will always come right back at every cessation of
current produced by the transmitting pendulum.
1
The total effect of currents whether weak or strong therefore is simply to move
the point of suspension of the pendulum through the same short horizontal distance
and thus the effect of varying currents is practically neutralized.
The use of the ordinary telephonic magneto call therefore producing a variable
and undulating current (and in combination with its own ordinary magneto alarm
bell) is thus rendered practically feasible.
The principle of application of the apparatus for all telephone and telegraph

page_text: systems is however the same, viz, that the calling currents are thrown on and off
the line circuit by the making and breaking of the contacts by the transmitting
pendulum while the receiving pendulum when it accumulates the proper arc of
oscillation knocks on one side a contact spring and so either unshort circuits an
alarm bell or other signal placed in the line circuit or else operates a local circuit
and makes the signal by means of a local current, and our system is evidently
applicable to any form of telegraph whose currents do not coincide in rate with
that of any of the receiving pendulums.
The arrangement at a telephone station is as follows. The line wire on one side
of the station is brought to the pivot of the telephone hook and the hook on its
upper contact completes the circuit through the magneto generator and bell coils
and thence through the coils of the receiving pendulum apparatus again to line on
the other side of the station. On its bottom contact the telephone hook completes
the circuit through the speaking and receiving telephones and the receiving
pendulum coils again to line for the other side of the station. The terminals of
the magneto generator are also coupled with the transmitting pendulum and
provision is made for short circuiting the bell as already described." When a battery
is used in place of the magneto generator the ringing key is between the upper
contact of the telephone hook and the bell. The zinc of the battery is permanently
connected with the transmitting pendulum apparatus and the key when depressed
leaves the contact which connects it with the bell and completes a contact which is
coupled with the copper of the battery. We prefer however to employ opposed
batteries at the two ends of the line in which case the key introduces a local earth.
.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Alfred Charles Saunders and Alfred Charles Brown in
the Great Seal Patent Office on the 20th October 1883.
HENRY ALFRED CHARLES SAUNDERS and ALFRED CHARLES BROWN both of
66 Old Broad Street in the City of London "IMPROVEMENTS IN TELEPHONE
OR TELEGRAPH CALL APPARATUS AND CIRCUIT ARRANGEMENTS
"
The object of this invention is to enable an operator at any one telegraph or
telephone station of a number of such stations in series on one line wire to sound
an alarm or make any other suitable call at any other one of the said stations
without disturbing the remainder.
This is accomplished by taking advantage of that property of pendulums by
which (when the propelling impulses are small) they will only oscillate continuously
in response to impulses given at their own proper rate of oscillation but will
periodically interfere and come to rest again when subjected to impulses given at
any other rate.
Reed vibrators have long been used for similar purposes but in applying them
to telephonic signalling a difficulty occurs in consequence of variations in the
currents. These variations arise in practice from a number of causes but chiefly
on telephone circuits from the variation of the resistance of the circuit when the
line is successively plugged through to a number of different lines. Then either
the weaker currents fail to accumulate sufficiently ample oscillation in the reed
vibrator or else the stronger currents exercise too much control over the reed and
bring it into operation when the next numbers are being called. More especially
is this the case when the currents used are those produced by the magneto
machines used in telephonic work. These currents being undulatory in their
nature and being subject to external variations from variations of speed in
turning
From the above mentioned and other causes reed vibrators are thrown into
vibration even when the rate of succession of currents is made very considerably
different to the proper rate of the reed. Our invention however enables these
magneto machines together with their own ordinary alarm bells to be used. We
employ a slower moving and more certainly isochronous gravity pendulum.
At each station of a number in series on one line we place a pair of pendulums
suspended in any ordinary manner one for transmitting and the other for receiving.
The apparatus is represented at Figure 1 of the annexed drawings. A is a board
to be fixed in a vertical position, upon it the other parts are mounted.
a is the
transmitting pendulum, it is suspended from the knife edges a¹ which are received
into V notches in the piece b. The transmitting pendulum is actuated by a single
impulse given to it by hand by the operator in calling. The impulse may be
given directly or through the intervention of a lever key. The transmitting
pendulum carries a movable bob a' capable of being placed in any position by the
operator the proper positions for each station to be called being denoted either by
notches cut in the pendulum rod or by a graduated scale placed behind. In any
case it is convenient to provide notches in the rod and a retaining spring to keep
the bob at the notch to which it is placed. This pendulum operates to make and
break electrical contacts by means of a light contact spring as extending out from
the rod immediately below the knife edges. The spring as the pendulum vibrates
oscillates between two adjustable contact points c' and c³. The relative duration of
make to break is adjustable by turning the contact screws out or in. Or the
electrical contacts may be made by the pendulum rod itself.
d is the receiving pendulum,

page_text: The receiving pendulums are actuated by the current by means of an electro
magnet e at each station. The coils of these several electro-magnets are in series in
the line circuit. The receiving pendulums each carry a bob which is placed at a
different position (or distance from the point of suspension) at each station on the
line. (The positions to which the bobs of the receiving pendulums are set
correspond in each case to one of the divisions on the scale for transmitting
pendulums at every station) and the length of the receiving pendulum is such that
it makes two vibrations to one of the transmitting pendulum. When therefore
the bob of a transmitting pendulum is placed at any particular height and the
pendulum started currents from any source are caused to flow through the contacts
which it actuates and along the line, only that receiving pendulum whose bob is
set to cause it to make that particular number of oscillations per second will
respond and accumulate a considerable arc of oscillation. The others will simply
after making a few small oscillations interfere and come to rest again. The
receiving pendulum which accumulates the oscillations knocks against a piece of
wire projecting from a light contact spring f' and lifts the said spring off a
screw stud g with which it normally makes contact. This contact when made
closes a short circuit around the coils of the bell or call signal which is in series in
the line circuit and since this contact is broken by the receiving pendulum at a
time when by the operation, of the transmitting pendulum a current is on the line
the call will sound at each oscillation. f is a weight or bob fixed on the springf¹,
it causes the spring to oscillate for some time after receiving a blow from the
pendulum d and so aids in keeping the circuit open through the bell. Or the
pendulum rod may be made to open and close local circuits.
.
In order that the pendulum d may be influenced equally or nearly so by strong
and by weak currents instead of attaching the armature h to the pendulum rod
and allowing the electro magnet e to attract the pendulum directly we suspend
the armature from knife edges h¹ and we then suspend the pendulum rod proper
to the bottom of the armature either by a thin flexible blade or spring or knife
edge d¹. At the back of the armature there is an adjusting screw i by which its
play can be limited to as small an extent as desired. The parts are so hung that
gravity draws the armature back against the screw stop i. Now since the armature h
is by this means always kept very close to the electro magnet the weakest current
capable of working the apparatus at all (and much weaker than any likely to be
experienced) will pull the armature right up to the magnet while the strongest
possible current can do no more; the surplus energy simply spending itself on the
poles of the magnet. The armature also will when sufficient time is allowed come
right back by gravity at every cessation of current produced by the transmitting
pendulum.
The total effect of currents whether weak or strong therefore is simply to move*
the point of suspension of the pendulum through the same short horizontal distance
and thus the effect of varying currents is practically neutralized.
The use of the ordinary telephonic magneto call therefore producing a variable and
undulating current (and in combination with its own ordinary magnetic alarm bell)
is thus rendered practically feasible.
The principle of application of the apparatus for all telephone and telegraph
systems is however the same, viz, that the calling currents are thrown on and
off the line circuit by the making and breaking of the contacts by the transmitting
pendulum while the receiving pendulum when it accumulates the proper arc of
oscillation knocks on one side a contact spring and so either un-short-circuits an
alarm bell or other signal placed in the line circuit or else operates a local circuit
and makes the signal by means of a local current. And our system is evidently
applicable to any form of telegraph whose currents do not coincide in rate with
that of any of the receiving pendulums.
The arrangement at a telephone station is as represented by Figure 2 and as
follows: The line wire k on one side of the station is brought to the pivot of the
telephone hook and the hook on its upper contact completes the circuit through

page_text: the magneto generator m and bell coils n and thence by the coupling p' through
the coils e of the receiving pendulum apparatus and coupling p³ again to line k on
the other side of the station. The bell coils are however short circuited by the
connection q passing to p³ thence to p. g. f'. p³ and pt. On its bottom contact the
telephone hook completes the circuit through the speaking and receiving telephones
and the receiving pendulum coils e again to line on the other side of the station
by the path already traced. The terminals of the magneto generator m are also
coupled with the transmitting pendulum by the connections 8 and q passing to pl
and p which are coupled respectively with the part b and the contacts c¹. c. of the
transmitting pendulum. When a³ touches c¹ or the generator is short circuited
but at other times the currents from it pass by p². p. g. ƒ¹. p³. p*. e and p³ to line k¹.
The bell is short circuited as already described. When a battery t is used in place
of the magneto-generator as is represented in Figure 3 the ringing key u is
between the upper contact of the telephone hook and the bell. The zinc of the
battery is permanently connected with the transmitting pendulum apparatus and
the key when depressed leaves the contact which connects it with the bell and
completes a contact which is coupled with the copper of the battery. We prefer
however as is represented in Figure 4 to employ opposed batteries at the two ends
of the line in which case the key introduces an intermediate earth through the
transmitting pendulum contacta
Having thus described the nature of our said invention and the manner of
performing the same we would have it understood that we claim :-
First The use of freely suspended gravity transmitting and receiving pendulums
calling into action the call bells at the several stations on a telegraph or telephone
line substantially as described.
Second Suspending the receiving pendulum freely from the armature of the
call electro-magnet the movement of which is controlled by a stop or stops; by
which arrangement strong currents are prevented from exerting an undue influence
on the receiving pendulum.
Third-The arrangement of apparatus substantially as described in respect to
Figure 1 of the annexed drawings.
•
Fourth-The circuit arrangements described in respect to Figures 2, 3 and 4.
In witness whereof I the said Alfred Charles Brown have hereunto set my
hand and seal this Nineteenth day of October in the year of our Lord One
thousand eight hundred and eighty three.
ALFD C BROWN. (L.S.)