Improvements in connection with Telephones.
Year: 1891

page_text: Date of Application, 31st Dec., 1891-Accepted, 6th Feb., 1892
UUMI LEID
Improvements in connection with Telephones.
We, ERNEST FRANK FURTADO of 48 Saint Pauls Road, Camden Square,
London, N.W., Electrician, and ANDERS, ELLIOT AND CHETHAM-STRODE
(LIMITED) of 10 Bush Lane, Cannon Street, London E.C., Electrical Engineers
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 :--
Our invention relates to improvements in connection with electrical telephono
apparatus, and the arrangement of the circuits thereof and therefor, the objects
of which are, Firstly-That by the employment of a single line wire a number of
subscribers stations may each be in electrical communication with the exchange or
central station, and capable of sending a signal or message thereto, or receiving a
signal or message therefrom individually, without in any way disturbing the
remaining subscribers upon the same line. Secondly-That by the particular
construction and arrangement of the local instrument at the station of each
subscriber, no two subscribers can communicate with each other, until a current
from the exchange or central station has operated upon both local instruments, and
placed them each in electrical condition to acquire this. Thirdly-That although
only one line wire is employed for a given number of subscribers, whose stations
are connected in series therewith, only those stations whose instruments have been
placed in electrical condition by the exchange as aforesaid for the purposes of
telephonic correspondence, can possibly overhear, or in any way participate in, or
break in upon the said conversation, until the same is finished and the corre-
spondents have automatically returned their instruments to their normal condition.
The method according to and forming the subject of our present invention is
based upon the following principles.
(a) That if a steel reed be set into vibration, and adjusted so as to be in close
proximity to a gong or bell, so that at every complete vibration when the fullest
amplitude thereof is attained, and the said reed touches or strikes upon the bell,
that each stroke is amply sufficient to give a powerful ring thereon.
(That if a given number of current impulses per second be made to pass
through an electro magnet with an armature tuned to give the same number of
vibrations as impulses of current per second, then the armature will vibrate in
unison with the current impulses. But on the other hand, if the current impulses
are not syncronous with the natural vibrations of the armature, or if the armature
vibrations do not form a harmonic to the current impulses then the armature will
not vibrate.
We are perfectly aware that the said principles are well known, and we do not
broadly claim them as forming part of our invention, except in combination with
the specially constructed apparatus herein described and shewn, and the method
adopted by us of employing the said principles in connection therewith, and so far
as we are aware the said combination is perfectly novel and not hitherto known
and used, and the construction use, and enjoyment of the said combination for our
especial benefit and profit is what we desire to secure by Letters Patent.
For the purposes of our said invention we provide at the central station or
exchange, an instrument which represents electrical signal and telephonic com-
munication with a given number of stations or subscribers (say 8), and within the
said instrument is arranged a corresponding number of steel springs or reeds, tuned
to different notes, neither one of which is a harmonic of the others, or a multiple
thereof, and these we use as contact breakers to throw different rates of electrical
impulses to line.

page_text: At each of the said stations, which are electrically connected in series with each
other, we place an instrument provided with an electro-magnet having for its
armature one such steel spring or reed, tuned-to give the same number of vibrations
per second as one of those at the exchange, and in sufficiently close proximity to
said reed we place a suitable gong or bell, but although each station has a reed
of corresponding pitch at the exchange norone station may be; or can be a harmonic
of another.
Now selecting one of the contact breakers at the exchange as an example (say
one breaking circuit 250 times per second) on passing a current through this it will
accordingly send 250 pulsations of current to line, per second, returning by way of
earth to complete the circuit. Now these pulsatory currents will cause similar
pulsations of magnetism in the aforesaid electro magnets at the subscribers stations,
as above described, which in turn will give a corresponding number of pulls per
second upon the tuned armatures above them, but, as of all the armatures at the
subscribers stations upon the circuit only one is tuned to vibrate 250 times per
second, it follows that that one is the only one that can vibrate in sycronism with
the pulls produced by the electro magnets, consequently the second pull would
neutralize the first pull, and so on upon all the armatures not syncronous with
that at the exchange, so that only the armature capable of vibrating in unison
with the periodic currents, can possibly attain sufficient amplitude of vibration to
strike the adjacent gong before referred to, suspended above the said armature.
In order that any one subscriber may ring up the exchange without affecting
the bells at the other subscribers stations, we provide at each subscribers station an
ordinary magneto-generator, or a battery push button, neither of which methods
of ringing would have any effect upon the harmonic bells of the other stations,
notwithstanding that the current may pass them all on its way to the exchange.
To guard against or prevent the possibility of the conversation carried on by, or
between any two subscribers upon the line, being overheard by the remaining
subscribers we provide that all the telephones circuits when at rest are cut out
from line automatically and cannot be put in again by the subscribers themselves,
but must be done by the exchange by means of a call or answered call therefrom.
For the purpose of effecting this we employ a novel and specially constructed
electro-magnetic device, on local circuit at each subscribers station, which is
automatically operated when contact takes place between the vibrating armature
and the gong, which closes and completes said local circuit, and this when closed
causes an electro-magnet to raise an armature from locking engagement with a
lever hook carrying the telephone receiver, so that this may be free to complete
certain switching arrangements when the receiver is removed therefrom. The
raising of the said armature partly breaks the local circuit just referred to, by
closing a second local circuit through the said electro-magnetic device that the
armature may be still held up thereby until after the receiver is removed from
the hook, which breaks the second local circuit through the magnet and places the
armature in a position ready to take its original place when the receiver is again
returned to the hook upon cessation of the conversation.
In order that our invention and the manner of its operation may be clearly
understood we have appended hereunto two sheets of drawings, in which
Fig. 1 is a front view of the apparatus supplied to each subscribers station,
the front of the case of which has been removed for the purpose of shewing the
internal mechanism.
Fig. 2 is a plan view of the instrument in use at the exchange or central station
for each circuit, in which we have chosen to presume that the number of subscribers
stations in connection therewith is eight only.
Fig. 3 is a vertical section of Fig. 2 taken between either of the vibratory reeds
thereof.
Fig. 4 is a view of so much of Fig. 1 as is necessary to illustrate the second
position of that part of the mechanism, when the telephone receiver has been
removed therefrom.

page_text: Fig. 5 is a view of part of Figs. 1 and 4 to be hereinafter referred to.
Similar letters of reference are used to indicate the same or like parts in all
the views.
In describing our invention and the manner of its operation we will first deal
with the exchange or central station, and the Figs. 2 and 3. Sheet 2, which
represents the apparatus thereat.
This consists of a base or frame A of wood slate or other suitable non-conducting
material upon which is mounted, or formed integrally therewith a block B of the
same or similar material to that of A, upon which is fixed by screws or the like
eight brackets or cockpieces C shewn in Fig. 2 by the numerals, 1. 2. 3. 4. 5. 6.
7 and 8, each of which is provided with a suitable contact screw a.
Upon B is
mounted a second block D of insulating material, to the upper surface of which is
fixed by screws or the like b a steel or other magnetic metal plate E, formed so as
to present eight equa-distant parallel tongues or reeds, shewn in the drawings by
the roman numerals I. II. III. IV. V. VI. VII and VIII, each of which is tuned
to be of a different pitch to that of its fellows, so that no one reed may be a
harmonic of, or capable of vibrating syncronously with another.
Or the said reeds
may be separate and distinet from each other if desired, and each fixed upon D by
a screw or screws b. In either case the said reeds are so arranged that when fixed
as stated their free ends are beneath the cockpicces C as shewn in Fig. 3. Upon
each of the reeds E we prefer to place, and fixed thereto by any suitable means a
platinum pointed fine plate spring c, at such an angle therefrom as to be in electrical
contact with the screw a of the companion cockpiece C when E is at rest, and
capable of breaking contact therewith at or about half the vibratory amplitude
of the reed upon which it is placed. In Fig. 2 only one such spring c is shewn
that being upon the reed II the object of this being that the reeds may be more
clearly seen in the drawing. An oblong electro magnet F is fixed by any suitable
means upon the block B between D and brackets C, the core of which is of a
length sufficient to embrace all, and magnetically influence any one of the reeds E,
when a current is caused to pass through the coils thereof. In Fig. 2 the
upper end of the bobbin of F has been purposely omitted to shew the winding
thereon. Or we may in certain cases, or where desirable provide in lieu of the
one universal electro magnet F a separate electro magnet for each of the reeds E,
but we prefer the former method.
Upon the block A and partly surrounding B is a metallic frame or plate G
screwed or otherwise fixed to A, and outside G but separated therefrom, is a
metallic frame divided into eight parts each of which is fixed to A by any suitable
means, and separated from each other a sufficient distant to prevent electrical
contact. A semicircular portion is removed from each of the pieces f, and a corre-
sponding portion from the plate G, facing each piece f, so that electrical contact
may be made between any one of the plates f, and G, by the insertion of a key or
plug switch in the circle thus formed, or any other suitable means may be
employed for attaining the same end. By reference to Figs. 2 and 3 it will be
seen that the plate Gis electrically connected to the positive pole of a local
battery H, the opposite pole being carried to earth at H, and that each section f,
is electrically connected to one of the cockpieces C, and that one terminal of the
winding of F is connected to E, the other being carried to line wire F', which
is the main lead to the eight subscribers stations in series and ultimately to
earth.
From the foregoing description of the apparatus at the exchange or central
station it will be easily understood that if the exchange desires to ring up one of
the subscribers stations that by placing a plug switch between either of the plates f
and the plate G, that a circuit would be closed thereby. As an example, we will
suppose that the exchange wishes to ring up the subscriber the vibrating reed upon
whose local instrument is tuned in unison with, say, the reed at the exchange
marked VIII in Fig. 2, the operator at the exchange would place his plug switch
so as to connect the plate G and the plate marked X in Fig. 2, the current would

page_text: then pass from the battery H, through G and fx to the cockpiece 8 Fig. 2, through
the contact point a, the reed and spring at VIII, the electro magnet F, to line F,
and presuming that the reed VIII is tuned to vibrate 250 times per second, it
follows that a pulsatory current would pass to line equal to 250 pulsations per second,
and as only one subscriber on the circuit has an armature capable of vibrating
250 times per second that armature would be the only one of the series that could
respond, to, or be operated upon thereby, and although the said current would pass
through the coils of each and all the stations in the circuit before reaching earth,
its influence would be neutralized by the non-syncronous movements of the
remaining armatures. The same operation from the exchange would be exercised
to ring up any station in the circuit, the only difference being in the placing of the
plug switch, so as to pass the current through the reed E whose vibrations would
create a pulsation in the current syncronously with the armature at the station to
be signalled.
A suitable gong or other sonorous signal and indicator would be provided at the
exchange in connection with each apparatus Fig. 2 in order that the attendant may
know which subscriber had signalled attention.
Referring now to the apparatus at each subscribers station and shewn complete
by Fig. 1 Sheet 1.
In carrying into effect this part of our invention we provide a casing I of any
desired shape or finish externally and made of any suitable kind of non conducting
material but preferably of wood, within which we mount an ordinary magneto-
generator J. connected at g to earth plate H, and to main lead F' at h, and so
arranged that by the tension of a suitable spring i, contact is broken at h when the
generator is at rest, and only made thereat when the handle K is rotated by the
subscriber when he wishes to ring up the exchange, this being the purpose in our
system for which the said magneto-generator is employed, although we may if
desirable employ other forms of electric generators, or electric energy derived from
other sources for this purpose.
Upon the top of the case I we fix a self contained bell, of any suitable type or
pattern but preferably consisting of a casing j, a pair of electro magnets kk³,
mounted upon a yoke piece fixed to the bottom of j. A reed or plate M, taking
the place and performing the duties of an ordinary bell armature, is mounted upon
the core of the electro magnet k¹ and is tuned to be capable of vibrating a given
number of times per second (say 250), and of such a length that its free end equals,
or slightly exceeds the radial dimensions of, and in sufficiently close proximity to a
gong or other sonorous signal N, mounted upon a standard m or its equivalent, fixed
by any suitable means within and to the case j. Within the case I is fixed an
electro magnet O, one terminal of the winding of which is connected to the yoke l,
the other to a spring n fixed upon the inner surface of the left hand side of I.
Also within the case I is a lever P pivotted at p, at which point its diameter is
extended to form a circular plate, part of the periphery of which is removed so as
to forin thereby a catch or shoulder q and a projection r, the latter being always
in rubbing and electrical contact with a metal rectangular spring s, or its equivalent,
fixed within I. The lever P extends through a slot s' in the side of I (see Fig. 5
Sheet 2) and terminates with a hook or fork for holding the receiver Q when this
is not in use, the weight of the latter keeping the former in a horizontal position,
resting upon the lower end of the slot s', against the tension of a spring t. Upon
the back of the lever P and preferably forming part thereof is a triangular
projection o, shewn more particularly in the view Fig. 5, which when P is at rest
and in a horizontal position as at Fig. 1 Sheet 1 is in electrical contact with the
spring n, but when Qis removed and P is raised by the tension of t, to the limit of
the slots, the said projection o breaks contact with n, and makes contact with two
similar but oppositely placed springs and v¹ fixed also upon the left of I. The
first contact between P and n is shewn at Fig. 1, the second between P and
will be better understood by reference to Figs. 4 and 5 Sheet 2. The purposes
of v v¹ will be hereinafter more fully explained.

page_text: The
To a pillar upon the base plate of the electro magnet O, and insulated therefrom,
is pivotted a hooked lever w, by the means of a screw insulated from w.
hook of w engages by the tension of a spring wi with the catch when P is at
rest as shewn in Fig. 1. Upon the lever w and insulated therefrom is a spring "
in electrical contact with y, and of such a length as to be capable of making
electrical connection with a contact pillar z, when w is raised by the influence of
the magnet O, as in Fig. 4 Sheet 2.
A call having been sent to the exchange by means of a current generated by J,
and assuming for the sake of illustration, that this is sent by the subscriber whose
reed or armature M is tuned to be in unison with the reed VIII at the exchange,
the operator thereat in order to answer said call would proceed to insert his plug
switch in the proper place to close circuit with the subscribers station in the manner
previously described, and the pulsatory current therefrom enters the subscriber
instrument Fig. 1 at L, and through the coils of kk', out at L' to line and ultimately
to earth after neutrally passing the farthest or last station on the circuit. The
passing of said pulsatory current through would create a corresponding
vibratory motion in the armature reed M, and when this has reached the highest
point of amplitude and the reed M has touched and sounded the gong or its
equivalent N, a local circuit is closed from a local battery H" which passes by
wire through the terminal, the gong N, reed M, core of ki, the yoke l,
magnet O, spring u, projection o lever P, spring s, and through " back to H".
The lever to would then be raised by the pull of O, from locking catch 9, until the
spring makes contact with as in Fig. 4, thereby closing a shorter local circuit,
through, 1, y, O, u, o P, s, back to H. The object of this second local circuit
being that we may still be kept up by the pull of O, when the current from the
exchange ceases, and consequently the vibrations of M, the contact between which
and N it will be remembered closed the first local circuit. The last closed local
circuit remains in force until the subscriber removes the receiver Q from P which
is then raised by the spring t as shewn at Fig. 4. The catch has then described
so much of an arc as to be beneath the hook of the lever w, by which it is
prevented from falling when the local circuit is broken by the separation of n
and o when P is raised as described, this will be clearly understood by reference
to Fig. 4.
The lever P thus raised makes contact with the two springs by the projection o
coming in contact therewith, and the apparatus is now in readiness for telephonic
communication with the exchange.
We may employ the use of any of the well known forms of transmittors in
general use, but for the purposes of illustration we have chosen to shew an ordinary
microphone represented in the drawings by J Fig. 1.
The local battery now passes current through terminals J", microphone J',
and primary of induction coil, the wire, to the spring ¹, and from this
through o, lever P, springs back to battery, the secondary circuit being from
line through P, spring, telephone Q, the wire, induction coil to
earth H
The subscriber in question which we will call No. 8 having made known to the
exchange by telephone which other subscriber he desires to correspond with,
say No. 4, the operator at the exchange places his plug switch in the circular space
between G and xx and so rings up the station required, which operation acts upon
the reed M at No. 4 station in precisely the same manner as that described in
relation to station No. 8, the vibrating armature reed M of No. 4 being tuned in
unison with the reed N, at the exchange, and the apparatus and local circuits at
station No. 4, as also all the other stations, being identical with that described by
Fig. 1, the same operation of all the parts takes place, in precisely the same manner
as that described when referring to station 8.
The operator at the exchange having removed both plugs connecting the
instrument Fig. 2 with the two subscribers in question, the local circuit of both
subscribers are now open for telephonic cominunication with each other, and as

page_text: before mentioned, all the other subscribers in the circuit being cut out until put in
by the exchange, the conversation being carried on between No. 4 and No. 8, or
any other two, cannot be overheard by the other subscribers, and should either of
the other subscribers ring up the exchange while correspondence is being carried
the unanswering of the call may be taken to indicate that the line is in use, or
other signals may be arranged to convey the same meaning.
on,
Should a subscriber upon one circuit desire to correspond with a subscriber upon
another circuit, the junction of the two lines by the exchange, may be effected in
the usual way.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is.
1st. For improvements in connection with telephones the employment of the
system herein set forth, and the construction and use of the apparatus herein
described and shewn in connection therewith, in combination with the principle
specified in the preamble hereof, connected and operating substantially as and for
the purposes herein described and shewn by the drawings hereunto appended.
2nd. For improvements in connection with telephones, the construction and use
of the apparatus employed at the central station or exchange, consisting of a
base A of slate wood or other non-conducting material, having attached thereto,
or formed integrally therewith a block of similar material B, upon which is
mounted another block of similar material D, carrying a suitable number of
magnetic metal reeds or tongues E, or a plate so formed as to constitute a suitable
numbers of such reeds or tongues, gradated in length, breadth and depth, or
otherwise constructed in such a manner, that each is tuned or pitched so as not to
be a harmonic of its fellows, or so that no two reeds of the series employed shall
be capable of vibrating syncronous to, or in unison with each other, whether
provided with a supplementary spring e or not. The manner of utilizing the said
reeds or tongues E as electrical contact breakers, by fixing upon the block B, a
similar number of cockpieces or brackets C, each provided with an adjustable
contact screw a, impinging upon the free upper ends of E or the spring c when
employed each of said reeds being connected to one terminal of an electro magnet,
or collectively connected with one terminal of an universal electro magnet F,
placed between D and C, beneath the reeds E, the opposite terminals of said
magnet or magnets being carried to line. The manner of arranging the metallic
plates f, corresponding in number to, and electrically connected in consecutive
order with, the cockpieces C, and capable of being individually electrically
connected by the insertion of a plug or other switch, with an universal plate G,
fixed upon A, and in electrical connection with one pole of a local electric battery
or generator H, combined and operating substantially as herein described and
for the purposes stated and shewn by Figs. 2 and 3 of the accompanying
drawings.
3rd. For improvements in connection with telephones the construction and use
of the apparatus employed at the station of each subscriber, consisting of a case
or container I of wood or other non-conducting material, provided with a suitable
magneto generator J employed for signalling the exchange, and having a spring i
for disconnecting same with line when not in use. The self contained bell or
other resonator N, with electro magnets k k¹, and armature M, consisting of a reed
or tongue tuned so as to be in unison with one of the reeds E at the exchange,
mentioned in the preceding claim, so that a pulsatory current fiom E, entering
at L, and passing through to earth, may set into vibration the reed M, which
striking N, closes a local circuit from battery H through magnet O, spring u,
projection o, upon a lever P, to springs and back to battery, thereby raising a
hooked lever W,
which making contact at z, by means of a spring w", on w, closes
a second circuit through, wo, O, u, o, P, s back to H". The manner of
automatically closing the telephone circuit by the removal of the receiver Q,

page_text: from the lever P, whereby P is raised by a spring t, making contact with
springs, so that a circuit is made through microphone J', primary of induction
coil, lead, to spring v¹, o, P, s and " back to battery H". The secondary
circuit passing from line through P, t, Q, secondary of induction coil J to
earth, substantially as herein described and shewn by Figs. 1, 4 and 5 of
the accompanying drawings.
4th. For improvements in connection with telephones the manner of employing
only one line wire or main lead as a means of electrical communication between
several subscribers and a central station or exchange, in combination with the
herein described apparatus. The manner of automatically cutting out all the
subscribers stations from telephonic communication with each other until opened
by the exchange by the means herein set forth, and for the purposes specified.
Dated this 31st day of December 1891.
GEO. THOS. HYDE,
4, Moorfields, Fore Street, London, E.C., Agent for the Applicants.