Improvements in Apparatus for Measuring Electrical Energy.
Year: 1890

page_text: .COMPLETE SPECIFICATION (AMENDED).
Improvements in Apparatus for Measuring Electrical Energy.
I, Professor ELIHU THOMSON, of No. 26, Henry Avenue, Lyun, in the State of
Massachusetts, United States of America, Electrician, 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:-
My invention relates to that class of electric apparatus which is adapted to measure
the consumption of electric energy in a circuit upon which lamps, motors, or other
translating devices are employed, and my invention, therefore, applies to the class of
devices called electric meters.
The object of my invention is to provide a means for simply and easily keeping a
record of the product of the current flowing and potential on an electric circuit,
feeding groups of lamps or other devices from alternating current mains, from
transformers, or from direct current supply mains.
Another object of my invention is to secure freedom from too great delicacy
of parts, simplicity of construction, and practical accuracy in an electric meter.
I employ in carrying my invention into practice, a coil which. responds to the
amount of current flowing through the consumption. devices, and I employ an
armature of considerable resistance which is in circuit between the terminals of the
supply mains, or in a separate circuit of constant current, and therefore responds to
the potential of the mains, such movable, armature being directly affected by the
imagnetic field set up by the current in the said coil, which is in circuit and conveys
current to the consumption devices,
I also employ a magnetic damper or retarder of the speed of motion of the
armature, which magnetic damper acts by the development in it of Foucault currents
or induction currents in a permanent magnetic field. Various modifications and
different embodiments of my invention may be made without departing from the
essence of the invention.
In the accompanying drawings I have shown how my said invention may be
conveniently and advantageously carried into practice.
Figure 1 shows a general view of the essential parts embodied in this one portion
of my invention.
Figures 2-and-3-show modifications.
Figure 1 shows a still further-modification-adapting the meter to a special kind
of registery.
Figures 5 and 6-are further-modifications-in-the-disposition of the parts, somewhat
similar to Figure-4.
Figure 7 is a view embodying similar-construction
Figure & illustrates-a-modification in the retarder or damping-device:
Figure 2 is a front elevation of the organization embodying another part of my
invention.

page_text: Figure 340 is an edge or side view of the same, a part being shown in section.
Figure shows in front elevation the circuit arrangement separately.
Figure shows a modified switching device from that in Figures 1, 2 and 3.
Figure 63 shows a modification in the arrangement of the actuating coils which
operate on the vibratory structure.
Figures 7 14, 8 15 and 9 16 illustrate modifications in the relative placing of the
coils for keeping up the oscillation of the structure through the influence of the current
flowing in the main coil or sections of coil.
Figures 10 11 18 and 12 10 illustrate modifications in the construction of the
oscillating parts of the apparatus.
:
Figure 13 20 shows in a diagrammatic way the switch devices as related to the
coils S, S¹.
Figures 14 21 and 15 22 show modifications in which the coils working in connection
with the main circuit coil are placed in circuits disconnected entirely from the main
or work circuit.
Figure 16 23 shows a device that may be used in connection with the separate
coil circuit preserving a constancy of current in the same despite variations of resistance
from heating.
Figure 17 24 shows a further modification in the circuits.
Figures 18 25 and 19 26 illustrate modifications in the arrangement of the
switching devices, and show how the direction of flow of current in the coils may be
reversed.
Figures 20 27,21 28 and 22 20 illustrate different methods of automatically varying
the magnetic field in the neighbourhood of a copper disc hereinafter referred to so as
to correct any variations in temperature.
Figures 23 30, 24 34 and 25 32 illustrate in detail a commutator hereinafter
described and applied to the construction of meters shown in Figure 1.
I will first describe my invention as embodied in a rotary ineter as illustrated in the
accompanying drawings Sheets 1 and 2.
In Figure 1, X is an upright shaft mounted on delicate pivots upon which is
carried a screw gearing for moving a registry or counter system or train D. On this
shaft is mounted, at some other convenient point, an armature A, composed preferably
when the instrument is to be used on alternating currents or direct currents ad
libitum, or for alternating currents alone, of a hollow series of coils without iron or
with-very-little-iron in the interior. These coils are preferably wound in as large a
hollow figure as the dimensions of the instrument will admit. They are also wound
in a similar manner to a Siemens' armature, or other form of armature, which gives
a continuously rotative effect when used with a commutator, C. The commutator C, is
made of as small diameter as practicable, and the brushes C' bearing on it are delicate
springs carrying small blocks- of metal, preferably, silver, resting on diametrically
opposite points on the commutator, on a line at right angles, or nearly so, to the
common axis of the large coils K, K, which surround the armature closely, and as
closely as possible envelop it.
These coils are made of coarse enough wire to carry the full load of current to be
measured without much drop in electro-motive force, and without heating. The
structure as thus constituted is a motor without iron cores, or with very 1
little-iron
in-its-structure; so as not to give induction or reactive effects when alternating currents
flow through it. It is connected so that the coils K, K', are either in series or
multiple are with each other in the circuit direct to the lights, or other consumption
devices so as to be traversed by the current feeding the lights or consumption
devices, or by another current corresponding to its amount. They could be traversed
by a fraction thereof if adjusted properly.
The armature A, is wound with fine wire, there being H considerable number
of turns traversed by a very small circuit in derivation around the lights, or other
devices, and to limit this current, as well as to adjust its strength. a resistance, B, R,
is interposed, which is of greater or less amount, as needed, or the resistance-of-the
structure-itself might be made efficient for this p
purpose

page_text: We have thus constituted a motor of simple construction which is responsive to
the energy supplied to the lights, and its rotative torque will be in proportion
to that energy.
The current in the fine wire on the armature A, is so exceedingly
small as not to give trouble at the commutator C, and the commutator itself, may,
therefore, be made so insignificant in size as not to involve friction, which would inter-
fere with the readings.
In order to give the motor so constituted a work which will be proportional to the
speed of rotation I place upon the shaft X a device in which Foucault or induced
currents may be generated by revolution, such as a copper disc, M, affixed to the
shaft X, and held at right angles thereto. The edges of the copper disc, M, run be-
tween the poles of permanent er-electric magnets of constant power which are shaped
to embrace or closely envelop the disc M. and of which there may be one or more
according to the damping action required. A small wound-armature or short eir-
enit might replace the dise M. Thus it will be seen that the disc M rotates in a con-
stant field that is not in any way influenced by the system of motor coils or the currents
moving in them.
The action is quite simple. As a load is thrown on or off the speed of rotation
of the motor is maintained in almost direct proportion to the load, and the regis-
fery at D is therefore accelerated or retarded in exactly, or nearly exactly, proportion
with the changes of load. An integrated reading therefrom gives the actual energy
supplied in working the lamps or consumption devices.
The instrument when properly constructed has a range of 1 to 50 or more.
In-Figure--2--the-same--instrument--is shown,--of--substantially--the--same--construe-
tien, the-armature-A-being--wound-on--a-suitable--earrier--preferably-with--little--mag-
net e--material--in--it,--or-with--
h--no---magnetie---material--although--when-continuous
rial: In-addition-to-the-esils-K, K',-there-is-in-Figure--3--a--parallel--winding- of--finer
wire-S-S';-which-assists-in-furnishing--the magnetie--field--in--which--the--armature-A
eurrents-are--alone--need--the--armature--A--may--contain--considerable--magnetie--mate-
the--con-
revolves:-This--winding--is--supplied-with-initial--energy--in--shunt--around
samption-deviees;-or--supplied-in-any--other--way--or--from-any-souree,--with-a--small
earrent--of-initial-energy--so-as--to--give-an--initial--field
In-faet--a--winding---even
traversed-by-a-battery-current--would--suffice -where--continuous--currents-alone--are--to
be-measured; -or-a-slight-power--permanent--magnet--might-be-obviously employed--to
replace-th-initial-field-winding.
Where-alternating currents are--used--it--is--preferable--to--supply--the--initial--field
directly, though-it-will-of-course-be--understood--that-it-may-be-supplied--indirectly
through-induetien, such-as-a-small--induction--coil,--and--in-faet-the--currents--delivered
to-the-whole--meter--may-in--the case of alternating-oirenit--eurrents, be--derived--in-
ductively--from--those--which--are--to-be--measured,-the-only-requirement-being-that-the
indneed--enrrents--be--related--proportionately-with-those-which-are-to-be--measured:
The Figure 2also shows--the-replacement-of-the--permanent--magnets--whose--poles
are--presented--to-the-copper-dise-M;-by-electric-magnets-which-may--be--energized--in
Bhunt-te--the-mains-when--continuous--currents-are-to-be--measured,--or--which--may--be
energized--by--a--separate--battery--eurrent,-when-as-in--Figure-3;-alternating--eurrents
are-te--be--measured-in-the--other--coils--of--the--instrument: The--connections--to--the
eeils--which-are--to-be--in--shunt--or-derivation-to-the-work-may-be-all-in-serit s-or-they
may-be-in--separate- derivation--from--the--mains,--independent--from--one--another;--any
connection-being-saffieient-which-supplies-the-energy-to-the-eirenit.
Figure-2-shows--the-same--arrangement--with-the-initial energy--or initial-field--de-
poles--in--place--thereof.-This-is--only--applicable--however to-measurement--ef---con-
viees- absent,-the-dotted--lines--indicating-the--application--of--the--permanent--magnet
tinuous or-direct-currents.
Figure-4-shows-the-structure--so--modified-as--to--resemble--more-closely-a-form-of
motor--in--which--iron-is--used. The magnet-poles N-S-have-wound--apon-them--in
the-ordinary-way--coils-K, K', while-the-armature A-is-as-before--in--eireuits--through
the-commutator--in--derivation--te--the--lights--LL', through--and--adjustable--resist-
ance, R-the-armature-being-wound-with--a--fine-conductor, and--either--containing-no

page_text: iron--or--being--composed--of-an--iron--armature--with--laminated--plates--in---the- usnal
War:
The--retarding--dise,-,-is-mounted-on-the-armature--shaft--and--near-the-poles,-S,
and--the--registery--gearing--is--hown--symbolized--at--D:-This--construction---is--only
applicable--to--eases--in--which--the--registery is desired-to-be-less--in--proportion-with-a
large-load--or-Humber-of-lights- L--than--with--a-small-number--the-dise; M-being-run
near-to-the-peles N, S, which-instead--ef--being--constant--as--in--the--previous--figare, is
subject-to-variation--directly--in-proportion-te-the--amount--of-current-flowing--to--the
tery-will-be-a-deereasing--registery--per-unit--cf-consumption--the---larger--the--load-
This--is--useful--in--some--cases-where-it-is-desired-to-discount-for-heavy-leads-and-make
lights-The-retarding--effect--will, however,-be--an--increasing--effeet--and--the--regis-
an-extra charge-for-small-leads.
In--Figure--o--the-arrangement-has-about--the-same--effeet;--the--armature--A--being
shown--as--having-an--inner-elose--eireuited--shell--'-nnder--the--winding-and- between
the-winding-and-the-ere-in-the-interior.
In Figure 6-the--armature--A;-and-the-retarder-M,-are--along-side--under--the--same
field--pole--the-retarder--M-being-in-this-ease-a-copper-erlinder-with--or--without--an
iron-enfer
gure--shows-a-ction -which--is----effe et-similar--to-that--given-by-the--eon-
struction--Figure 3. The armature A revolves between-field--poles--energized--by--the
eois-K-K',--in-series-with-each-other-and-with-the-lights--L, L'-The-magnetie--poles
eause-rotation--of-the-armature-A-which-is-in-derivation-from-the-main--m,--through--the
winding T-Ton--another-set-of-poles-to-the-other-main--n-or--rather--to-a--connection
from-sueh-main-through-the-coile KK; to the group-of-light. This puts--the--arma-
tare A-and-the-eeils--T-T-in-series, while-they-are-in-shant-to-the-lights--together.
A--revolving-mass--of metal, such-as-a-copper-cylinder,-or--even-a-solid--bleek-of-brass,
iron-or-any-other-structure-in-which-Foneanlt-or-induced-earrents-may-be-developed
by rotation-in-a--magnetic-field-is--earried-by-the-shaft-X-in-front-of-the--poles -ereated
by-the-coils-T-T
The--registery--mechanism--D--is--aetnated-by-the--rotation--of-the--shaft--as--before.
which-flows--to--a--small--amount,--while-the--windings-K;-K',-are-coarse-and-will-earry
The--windings A, T, T-are-of-course-rather-fine--and--calculated-to-limit--the-eurrent
the-fall--current--readily--or--a-determinate fraction-thereof,-which-is-required-to-supply
all-the-lights L, L', in--multiple-Any--increase--in-the--load--L--L--inereuses--the
strength--et--the--poles-N, S,-while-the-armature-A-s-supplied--with--a--constant--OHP-
rent--due--to--its--being-in-a-high-resistance-eirenit-between-the-mains-m;-n,-assuming
of-course--that--constant--potential--is--maintained--at--the---terminals,--or--between--the
.maius-m-nr.
The--torque--developed-by-the-armature--under-these-conditions-will-be-proportional
to--the--strength-ef the field--N-S,-which-is-proportional,--below--saturation, with--the
eurrent-in-the--coils--K,-K¹.
The--retardation-of-the-dise-K-will-increase--as-the--speed--rises--and--proportionally
therete-as-the-field-in-which-it--moves--is--substantially-constant--with-constant--poten-
tiel-between-the-maine-m, n
G
The--action--then-will--be--very- similar-to-that-of--the-arrangement-Figure-1 under
changed-potentials.-In-Figure-1-a-change-of-potential--between--the--mains--inereases
the--torque-and-speed--of--turning In-Figure 7-the-same-action--of-increase-of-urma-
tare--current-takes-place-on-increase-of--potential--between--the--mains,--but--this--effect
is--counteraeted-by-the-inereased--retardation-given--by--the--coils--T, T', -aeting-o: -the
dise-M,-which-coils-T-T-are-also-responsive--to-the-inereased--potential--and--inereuss
of-field-in--which--the--dise--M--moves-so-that-the-device-Figure-1-is-an-energy--meter;
and-responds--not only-to-increase--and--decrease-of enrrent-but--also--to--increase-or
decrease--of-potential,-while-the-arrangement-of Figure 7 is--more--strictly--u--eurrent
meter-as-the--effect-of-inereare--or--deerease-of-potential-is-compensated-for-The-de-
viee-Figure---will--approximately---measure--the---energy--supplied--while--that-of
Figure 7.-will-measure--simply the current---supplied--without--responding-proper-
tionally-to-the-potential.

page_text: ductor M-has-been-shown as revolving it could be replaced by the magnets them,
selves revolving while the dice remains stationary, as indicated in Figure-&-und
this structure-may be adopted-in-some-cases.
I will now describe my invention as embodied in an oscillating meter as illustrated
in Figures 9 to 262 to 19.
Referring to Figure 92, L indicates a pivoted lever or structure mounted on a suit-
able pivot or bearing at P, and arranged to oscillate in a vertical or a horizontal plane,.
or any other plane as desired. The knife edge pivots for the structure are mounted
on a suitable frame and back-plate B, as shown.
D indicates a coil or section of coil of few turns of coarse wire which is connected to
and placed in the circuit in which current flows in amount varying with the electric
energy consumed. Preferably it is placed in the direct or main circuit with the
energy users, such as electric lamps or other devices supplied in multiple so that the
whole current is caused to traverse the coil D.
The coil D, in the active coil by whose action or by the action of current in which
an oscillation of the lever or structure L, is maintained with a rapidity dependent
upon the amount of current so long as current passes. The intermittent or oscillatory
action of the lever is kept up by a suitable device or commutator and the motive
influence is produced through an action of the electric current, and preferably by an
electro-dynamic action of the coil D.
In the apparatus shown in Figure 2 which is a preferable form of my invention, I
employ in connection with the coil D, which is fixed upon a suitable base-plate B, two
coils S, S', placed as nearly as possible in the same axis as coil D, or in the magnetic
field of the same. The coils S, S1, are mounted on the lever L, in any proper manner
and spring from side to side under the repulsive influence of the coil D. When two
separate coils S. S', are used as shown, the circuit controller or commutator acting on
the same may be made to throw them alternately into circuit, though it would be
entirely possible, though not to be preferred, as will hereinafter be apparent, to reverse
the current in the coils and to keep them both in action at all times, each coil being
made to operate alternately by repulsion and attraction. The coils S, S¹; are in a
circuit separate from D, and usually carry a constant current for which purpose they
may be placed in a branch passing from one to the other of the mains or leads sup-
plying the translating devices in multiple as when such mains or leads are of approxi-
mately constant potential. The coils S. S', which are preferably of quite fine wire.
may be connected into circuit and wound so that they will be alternately repelled
from the space inside the coil D, or be attracted thereto, the former being the much
preferred method.
In the apparatus shown in Fig. 2 they are thrown alternately into circuit at or
near the extremes of vibration of the structure L, by means of a suitable circuit con-
troller or commutator. This controller or switch may be of any desired construction
and operated by means of the lever L, directly or indirectly. A form suitable for the
purpose consists of a lever L', pivoted so as to be capable of swinging independently
of the lever L, and mounted preferably, on an independent support, as shown at p
Figure 40 3. The two ends of the lever L', or the contact points as such ends are insu-
lated from one another and are adapted to dip alternately into the mercury cups V, VI
for the purpose of closing an electric circuit. The terminals of the coils S, S¹,
Figures 2 and 3 are at one end joined together and connected through the pivot l'
and bearings, or by other means, with one terminal of the meter. The other
terminals of S, S¹, are carried separately to the two arms of the switch or commu-
tator, as shown in Figure 34. The mercury cups V, V₁, connect or are connected
together and with the opposite terminal or other side of the circuit which is to be
attached to post a, in the figures.
In this case the connections of the coils S, S', when in circuit through one or the
other will be in shunt to the translating devices or the mains feeding such translating
devices, the energy of which is to be measured or metered. It will appear that such
connection may be modified in the construction of subsequent figures. The coils

page_text: themselves may be made of sufficient resistance to check the current in this branch,
or they may be in series when in circuit, with a specially introduced resistance for
the purpose of keeping down the current to as small an amount as will operate the
mechanism.
Movement is communicated to the switching or commutating devices by means of
pius. carrying the weight W. These pins should be adjusted far enough apart so
that each will engage with the lever L, and swing it over to change the circuit only
after the lever L, has nearly completed its movement from one extreme of vibration
to the other extreme under the influence of the coil S, or S¹, acted on by coil D, or
the current in it.
.
In the positions of the parts shown, if the action is a repulsive action only,
the coil S, is the coil in circuit. The repulsive action between D, and S, swings the
lever L, over towards its opposite extreme until finally, just after the centre of
vibration in that direction is reached, the pin 7, on such lever will engage with the
lever L, and swing and the weight W, over the centre to the right after which the
weight W, will complete the movement of the lever L', and change the connection to
the mercury cup V, thus throwing coil S', the circuit and the coil S, out of circuit.
The latter will now be put in position to be acted upon by coil D, and a repulsion and
movement or oscillation of the lever L, in the opposite direction will now take place.
Near the completion of the reverse movement just described, the circuit controller or
commutator will be shifted by the other pin and the movement will be repeated.
Thus a continued oscillation of this structure will take place so long as current exists
in the coil or circuit D.
Z, Zare stops, preferably elastic, with which projections from the lever L, engage
to liggit the oscillations of the structure. These stops are preferably made as springs
and will then operate to cause a little rebound to assist the reversal movement or
change from one phase of vibration to the other. The weight W, has the effect of
producing a sudden and positive movement of the switching or commutating devices
at the instant when a change or reversal of the oscillation is to take place. Suitable
stops limit the play of the switch L'.
In combination with the oscillation structure I employ a damping or retarding
device, which is usually a magnetic damper consisting of a plate of copper C or other
good conductor rather thick, or a closed band or circuit, and a permanent magnet H,
or electro-magnet or other device for producing a magnetic field in which the copper
plate shall be moved. In the organization shown in Figure 2, the plate C, is carried
by the lever, and the magnet H, is stationary.
It is obvious however, that the magnet or other device producing the field might
be carried by the structure and the plate be stationary. Again, both might be moved
oppositely by the motion of the lever L. The effect of this device is to cause the
structure to oscillate slowly and deliberately upon the action of the movement
producing coils which carry the current to be measured. The magnet H should be
rather powerful so as to produce an intense field for the copper plate or closed
conductor to move in. The effect of the plate is to consume or absorb the energy of
oscillation imparted by the dynalic action of the coil D upon the coils S, S', or other
device.
A register or record of the oscillations of the structure may be kept in any desired
manner. One way of keeping a registry, indicated in Figure 2 consists in causing
the lever L to operate on the pawl of a register train; as shown each oscillation moving
such register. Other methods of registering the oscillations besides this purely
mechanical method may of course be employed but as these are at present well
understood in the art, I will not here describe them but may mention that the circuit
through either S, S', may contain an electro-magnetic device which on the completion
of such circuit operates the pawl indirectly.
The oscillations are best registered by means of a pawl T carried by an arm or
extension from the pivoted structure L, as indicated in Figure 147. The means for
registering recording or keeping tally of the number of oscillations of the structure

page_text: form, however, no part of my present invention which relates rather to the means for
producing and maintaining the oscillatory movement in the proper manner.
The switching lever L', might be arranged as shown in Figure 25 having above
its pivotal points a magnetic armature or piece of iron I, opposite stationary magnetic
surfaces M. The ends of the lever L', work in mercury cups V, V₁as before or other
contact devices to shift the current are used, as before explained. Between the
armature 1, and the magnet M, is exerted an attraction the action of which is to cause
a sudden shifting of the lever L', when the armature passes over the pivotal point or
point of greatest distance from I to M. This device takes the place of the movable
or oversetting weight W. The operation of the lever L', is produced by engagement
of pins, carried by lever L, with the lever L'. On movement in one direction the
armature I approaches the magnet M, when circuit is closed at V, and this remains
closed until forcibly again separated by the reverse movement, whereupon the lever L',
suddenly shifts and closing at V, at the same time brings the armature I, towards
the magnet M, on the side of the pivotal point opposite. The advantage of the
magnetic device is that it will work without being lowered.
The details of switching or commutating devices may be indefinitely varied without
departing from my invention and it will be sufficient to use any circuit controller or
commutating devices such as is used with any oscillatory or vibrating structure moved
by electric currents for the purpose of changing the circuits or electrical conditions
at or near the terminations of each oscillation for the purpose of producing a con-
tinuance of the movement but in a reverse direction.
:
It is not essential that two coils S, S₁, Figure #2 be placed together in line axially
as shown as they might be separated as shown in Figure 43 6 one above and one
below, the one on the end of one arm and the other on the end of another distinct
arm of the oscillating structure L, which, as stated before may be pivoted vertically
or horizontally or in other planes. In this case the direct current coils D. D', may be
placed in two pairs and act on each coil S, S', or there may be a single coil D, or D',
placed laterally alongside of the coils S. S The action is to throw out repel or
attract the coils S, Si, according to which is in circuit. The damping device may
also be duplicated as at C, C', and the fixed magnets for acting thereon may be H. H¹,
It will be seen that the magnets H. H', might be movable and the copper plate C. C¹,
might be fixed without changing the relations substantially.
Another arrangement of the coils D, D', which I have found to be quite effective
is illustrated in Figures 18 and 46 9. In this case a double coarse wire coil D, D¹,
traversed by the current as before explained or in any of the ways hereinafter
explained, acts to repel from its centre laterally the coils S.St,alternately (Figure 15 8)
according to which is in circuit. The coils S, S', are carried on the lower end of the
pivoted structure L as shown. The repulsion of one draws the other in between the
coils D, D. and such movement of repulsion at or near the completion of oscillation
of structure L. followed by the switching of the current by the commutator or switch
lever so as to produce an action of the coil D upon the other coil S, and a reversal
of the movement through the repulsion of such latter coil.
As before stated I may depend upon either attraction or repulsion and instead of
using two coils S, S¹. I may in such case use a single coil under the influence of the
coil D. Such modification is indicated in Figure 18. Here the commutating
device consists of two levers L, L', each having the two mercury cups connected as
shown to the terminals of the coil S, and adapted to reverse the circuit through the
same, as is well understood in the art. The device shown is typical of any commu-
tator, working to reverse a circuit. In this instance the current flowing in one
direction through the coil S. produces attraction between D and S, tending to oscillate
the lever L. in one direction. At the completion of the movement of I, the
commutator is shifted as before described thus reversing the connections of S. and
producing repulsion. This arrangement is, however not to be preferred as it
duplicates the switching devices.
By using the reversing commutator for the oscillating structure, a single electric
coil D, with direct currents might be employed as indicated in Figures 26 19 where in

page_text: the place of the two coils S, S¹ Figure 447, I have shown two permanent
magnets H H one having its north and the other its south pole arranged to enter
the axis of the coil D. The magnets are carried by the oscillating structure, as before,
and the coil D, has its connections carried to the reversing commutator.
In all of the preceding arrangements and in the arrangements to be presently
described, it is obvious that the electro-dynamic coil D, might be either on the
oscillating structure or on a fixed support as desired, that the part upon which it uets
inductively being suitably placed with relation to it.
In the modified construction shown in Figure 10 the damping device is con-
nected to the oscillating structure L, by means of a link K, which connects L, to a
second lever L carrying the copper plate C. The connection might be through a
segmental rack, as indicated in Figure 18 11. The coils in this case instead of
moving in and out of one another move to and from one another simply in the
direction of the magnetic axis. Otherwise the organization and operation of such an
apparatus when combined with the proper switching devices or commutators would
not differ from that of Figure # 2. The arrangement Figures 17 10 and 18 11 is not
so desirable, however, as the range of movement of the parts while in inductive
relation to one another is comparatively limited.
In the modification shown in Figure 10 12 the rock bar carries two separate
levers L, LA, directly attached to it, one lever carrying the coils S. S¹ or equivalent
part of the structure and the other two copper plates C C'. When the coil or
coils D, Dare made to operate electrodynamically on the coils S, S₁ it is not necessary
that the latter coils should be in connection from a circuit carrying the current to be
measured, although when the potential across the two sides of such circuit is fairly
constant, it is desirable to so energize them. As indicated in Figure 14 however,
they might be fed by connection with a separate source of energy such as a galvanic
battery B, provided such source of energy is fairly constant in strength. This is a
modification which may be employed when the currents are continuous currents.
The arrangement before described however should be employed in the case of alter-
nating currents.. The battery current might replace the branch connection when the
object of the meter is to register current irrespective of potential.
When the potential of the mains is very high or where it is desirable to vary the
proportion of energy delivered to the coils S, S', I prefer to employ an arrangement
such as shown in Figure 22 15, in which I have shown a transformer whose primary K.
is connected in derivation across the mains, while its secondary B₁, applies the
circuit of the coils S. S¹. By moving the core L of the transformer, or by otherwise
adjusting the potential that shall be set up in secondary, the proportion of current in
the coils S, S', may be adjusted.
In some cases there may be a liability to derangement of action of the meter from
variations of resistance in the circuit of the coils S, S either from heating of the coils
themselves or by changes of resistance at the contacts of the switch or commutator or
from other causes. To avoid this difficulty I propose to supply the coils S, S¹ with a
current which is automatically regulated so as to be constant in amount despite any
changes of resistance in the circuit. Any means may be employed for this purpose,
but for alternating currents I prefer to use a constant current transformer, such as
indicated in Figure 23 16 the primary K, of which is connected to any suitable source
as for instance to the mains ab while its secondary coil B connects with the circuit
of the coils S or S. By this means the current in the circuit of coils S, S' will be
kept constant so long as constant potential is maintained in the coil K.
The arrangement shown in Figure 45 8 also permits the raising or lowering of the
potential by changing the winding.
As before stated it is not necessary that the coils D should be in the main circuit.
Thus as shown in Figure 24 17 the coils D, D' are to be supplied from the secondary B
of a transformer, the primary K of which should be in the main circuit. The fixed
coil or coils of the meter S, might be placed in a shunt to the mains. In this
organization the coils D, D' may be carried by the oscillating structure, and the coil S
by fixed or vice-versa, the coils might be carried by the structure and moved between

page_text: lamps will be illuminated and extinguished in the same manner as when the
lamps are placed as illustrated in Figure 1.
In systems of electrical intercommunication, such as above described, it is
sometimes desirable, after two persons are in communication, to bring a third
person into communication with the other two. To facilitate this, I may provide
each subscriber's instrument with a push button 47 arranged to operate a spring
brush 48 normally in contact with a contact piece 49, but adapted, when the
button 47 is pressed, to make contact with a contact piece 51. The brush 48 may
be connected to the receiver hook 38. The contact piece 49 may be connected to
the wire leading to brush 25, and the contact piece 51 to the return conductor K.
The effect of pressing the button 47 is to interrupt the circuit as to brushes 24
and 25, and brush 28 and ring 26, without affecting the circuit through the
telephone receiver and transmitter.
Supposing, now, that station A has called station C, and is in communication
therewith, as shewn in Figure 1, and that it is desired to bring station B into the
circuit, the person at station C may operate his calling transmitter to connect with
station B, the same as if he were not already in communication with station A,
thus connecting his service wire J with the service wire J of station B (and like-
wise connecting station A with station B, since the service wires of A and B are
already connected) but breaking the contact between brushes 24 and 25 of his
transmitter, and closing contact between brush 28 and ring 26 of his transmitter.
This completes talking circuits between both stations A and C with station B,
stations A and C being connected to one side of the battery and station B to the
opposite side thereof; but while the parts are in this condition, operation of the
ringing lever 34 at either station A or station C will ring the bell at that station
only, because the circuit from the other station through the hell magnet a
station B will not be interrupted. But if, while the parts are in this condition,
the button 47 at either station A or station C be pressed, the circuit through
contact pieces 28 and 26 at that station will be interrupted and the common
return connection will be re-established. The ringing lever at the other station
may then be operated, ringing the bell at station B, while the person at that
station at which the button 47 is pressed can hear the progress of the ringing
and can hear when station B answers, the integrity of the circuit through his
transmitter and receiver not being affected by the operation of button 47.
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
1. In a system of intercommunication, the combination of a central station
having switches for connecting the several subscriber's stations, an electric gene-
rator, common return connections for one pole of said generator and for the sub-
scriber's stations, a service conductor connecting each subscriber's station with a
central station switch adapted, at will, to connect such service conductor with the
corresponding service conductor of another station, a second conductor for each
subscriber's station, connected to that terminal. of said generator opposite the
common return side thereof, and contact mechanism whereby when the service
wires of two subscriber's stations are connected, the connection of one of said
stations with the common return is broken.
2. In an automatic system of intercommunication, the combination of a central
station having switches for connecting the several subscriber's stations, service
and switching circuitconductors connecting eachsubscriber's station with a central
station switch, common return connections for the service and switching con-
ductors,and central energy means for supplying current to the talking andswitch-
ing circuits.
3. In an automatic system of intercommunication, the combination of a central
station having switches for connecting the several subscriber's stations, service
and switching conductors connecting each subscriber's station with a central

page_text: station switch, common return connections for the service and switching con-
ductors, and a generator for supplying current to both the talking and switching
circuits.
4. In an automatic system of intercommunication, the combination of a central
station having automatic switches for connecting the several subscriber's stations.
an electric generator, common return connections for one pole of said generator
and for the subscriber's stations, a service conductor connecting each subscriber's
station with a central station switch which is adapted, at will, to connect such
service conductor with the corresponding service conductor of another station, a
switching circuit conductor for each subscriber's station, connected, through the
operating device of the corresponding central station switch, to that terminal
of said generator opposite the common return side thereof, and contact mech-
anism whereby when the service wires of two subscriber's stations are connected,
one of said stations is connected to the generator through its switching.conductor
and the other through the common return.
5. In an automatic system of intercommunication, the combination of a
plurality of subscriber's stations each having apparatus of communication includ-
ing a magnetically operated calling device actuated by the completion of a circuit
connecting its station with another, a central station having switches for connect-
ing the several subscriber's stations, service and switching conductors for con-
necting each such station with the central station, a calling transmitter at each
subscriber's station, common return connections for the service and switching
conductors, an electric generator connected to said common return and to the
switching conductors, common return and switching circuit contacts in each call-
ing transmitter, arranged when closed respectively to connect the apparatus of
communication of that station with the common return and with the switching
circuit, and means operated by the transmitter for closing one such contact when
in the normal position and for opening such contact and closing the other after
said transmitter has operated to call another station, whereby calling of stations
other than that with which connection is finally established is avoided.
6. In a transmitter, the combination of an indicator adapted to control the
operation of circuit varying mechanism, and two contact devices, one arranged to
be closed when the indicator is in normal position, and to be opened when said
indicator is moved from normal position, the other arranged to be closed when
said indicator and circuit varying mechanism are operated.
7. In a transmitter, the combination of an indicator adapted to control the
operation of circuit varying mechanism, and two contact devices, one arranged
to be closed when said indicator is in normal position; and to be opened when said
indicator is moved from normal position, the other normally open, and means
operated by the circuit varying mechanism for closing said latter contact when
it comes to rest after operating.
8. In a transmitter for automatic systems of intercommunication, the combina-
tion, with an indicator and circuit varying mechanism controlled thereby and
adapted to operate a central station instrument through a switching circuit, of
return line and switching line contacts through which instruments of communi-
cation may be connected alternatively to the return line or to the switching cir-
cuit, one of said contacts being open and the other closed when the indicator is in
normal position, and means for closing that contact which is normally open and
for opening that which is normally closed when said indicator is moved from
normal position.
9. In a system of electrical intercommunication, the combination, with a
plurality of subscriber's stations, of calling means therefor comprising an electric
light at each station andmeans whereby the same maybe illuminated at will from
a distant station.
10. In a system of electrical intercommunication, the combination, with a
plurality of subscriber's stations and circuits and appliances for connecting the
same, of calling means for said stations comprising an electriclight at each station

page_text: and means whereby the completion of a circuit connecting two stations may illu-
minate a lamp at one of them.
11. In a system of electrical intercommunication, the combination, with a
plurality of subscriber's stations, and circuits and appliances for connecting the
same, of calling means for said stations comprising an electric light at each
station, means whereby the completion of a circuit connecting two stations may
illuminate a lamp at one of them, and a switch whereby response to a call auto-
matically extinguishes such lamp.
12. In a system of electrical intercommunication, the combination, with a
plurality of subscriber's stations having apparatus of communication, and cir-
cuits and appliances for connecting the apparatus of communication of said
stations, of electric lamps for illuminating said apparatus, means for supplying
current to said lamps and circuits, and automatic switches actuated by the opera-
tion of said apparatus of communication and arranged when actuated to illuminate
their respective lamps.
13. In a system of electrical intercommunication, the combination with a
revolvable ratchet wheel of two independently pivoted pawls engaging said wheel
on the same side thereof, an actuating device for directly reciprocating one of said
pawls, and a connecting device connecting said pawls and arranged to impart
motion to the other of said pawls so as to cause it to reciprocate in the opposite
direction to the reciprocation of the directly actuated pawl, substantially as and
for the purpose specified.
14. In a system of electrical intercommunication, the combination with a revolv.
able ratchet wheel, of two pawls therefor, separate adjustable pivots or trunnions
for said pawls, whereby they may be adjusted laterally and independently, au
actuating device for directly reciprocating one of the pawls, and a connecting
device connecting said pawls and arranged to impart motion to the other pawl so
as to cause it to reciprocate in the opposite direction to the reciprocation of the
directly actuated pawl, substantially as and for the purpose specified.
15. Apparatus having its parts constructed, arranged and adapted to operate
substantially as described with reference to Figures 2 to 8 of the accompanying
drawings, for the purpose specified.
16. Apparatus having its parts constructed, arranged and adapted to operate
substantially as described with reference to Figures 9 to 13 of the accompanying
drawings, for the purpose specified.
17. A system of automatic electrical intercommunication having its parts con-
structed arranged and adapted to operate substantially as described with reference
to the accompanying drawings for the purpose specified.
Dated this 23rd day of A
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.