US991928A - Telephonic relay system. - Google Patents

Description

C. G ASHLEY. TELBPHONIG RELAY SYSTEM.

APPLIOATION FILED JULY 24, 1909.

991,928. Patented May 9, 1911.

2 SHEETS-SHEET 1.

C. G. ASHLEY.

TBLEPHONIG RELAY SYSTEM.

APPLICATION FILED JULY 24, 1909. 991,928, Patented May 9, 1911.

2 SHEETS-SHEET 2.

v w 5 .m w m M A /IV| M AQ 7 CHARLES Gr. ASHLEY, OF CHICAGO, ILLINOIS.

TELEPHONIC 'RELAY SYSTEM.

Specification of Letters Patent.

Application filed July 24, 1909.

Patented May 9, 191.1.

Serial No. 509,250.

To (all whom it may concern:

lie it known that 1, CHARLES G. AsnLeY, a citizen of the United States of America,

and a resident of Chicago, county of Cook,

circuits possessing large capacity, as, for

example, long distance tQlGPllOHU circuits, to which end, I impress current upon an inducing wiudinc from a source indcpcmlent of the telephonic current and modify this can rent byv the telephonic current, there being an induced winding or member in association with thisinducing windin that serves to impress current upon the telephonic circuit, which current corresponds tclcphonically to the telephonic current; originally impressed, but which is of greater value, whereby the receiving telephone instrument is suln ject to a, stronger telephonic current than that it would otherwise be subject to were it not for the employment of this inducing wind inn with its separate source of supply, the induced winding, and the agency whereby the telephonic cijirrei'it that is to be reinforced cli'ects a modification oi the current in the inducing winding.

I have been able by means of my invention to construct an apparatus that will. enable the conduct of conversation over a single telephonic circuit in both directions. The instrumentality that I prefer to employ for impressing the inducing winding with the current that is to be modified by the incoming telephonic current, is a well, constructed form of the so-called uni-polar dynamo or generator, the terminals of which are connected with the terminals of the inducing winding (of very low resistance) to supply thereto current of comparatively large volume and small pressure, a unidirectional current of ten amperes with a pressure of five-tenths of :1 volt giving good results. Such current condition is '1naintained in said inducing winding when the telep-l'ione circuit is not in use, the means employed for the purpose of maintaining this current in the inducing winding preferably residing in a local ircuit including a battery and an exciting coil produclng a field in which the armature ()if the generator rotates. This tield, however, may be furnished by a permanent magnet. lly rotating the armature at a uniform-velocity through this field, which is (It? uniform in density, a cur rent of constant volume and pressure is impressed upon the inducing winding as long as the telephonic circuit is inactive. In order that the current; in this inducing winding may be moditicd, I employ a modifying winding that is subject to the telephonic current initially impressed upon the telephonic circuit and which is adapted to produce in the same field of the uni-polar generator a supplemental llux that adds to and detracts from the 'tlux density, acccn'ding to the wave of the telephonic current. This augmentation and diminution of the flux density causes a (f ll05} )0lltllfl 2' change in the character of the current impressed upon the inducing" winding, the voltage and the current both being changed. The induced winding. by reason of its inductive relation to the inducingwinding, has impressed thercupon current whose pressure is determined by the ratio of transtormation between the induced and the iudueii'ig' winding, the induced current being stepped up in pressure, whereby outgoing; telephonic current is impressed upon the telephonic circuit at the rolay of far greater value than it is impressed upon the relay. to enable the proper opera lion oi. the receiving telephone or instrument that otherwise would oiily be subject to cxtreinely weak telephonic current. Thus, a mechanical agency, the power that drives the armature of the uni-polar generator, is employed to step-up the telephonic currents at the relay and, in fact, this mechanical agency may alone be relied upon as the initial agency for this funetiom if the iron of the field is permanently n'iagnetized, or, assuming that the armature has been brought to the proper speed, for in this case the field exciting battery or other equivalent source of current (and by battery I mean any suitable form of exciting source of current) may be replaced by a shunt connection with the brushes or terminals of the armature, though I prefer to employ the battery or separate field excitation. The induced winding may be a single coil in bridge between the sides of the telephonic circuit, in which case the inducing winding is also a single coil or said induced Winding may be subdivided into two coils. one in association with one telephonp1 station andthe other in association with te other telephone station or receiving station (for it is obvious that more'than one instrumentality fior relaying telephonic currents in a telephonic circuit may be employed at intervals along the cir is preferably common thereto.

cuit). 'VVhere the induced winding is subdivided into two coils, the inducing winding Where the induced winding is in asingle coil, it is preferably in bridge of the telephonic circuit, while the modifying winding is desirablyin series in the telephonic circuit. In order that the inducing winding will not react upon the modifying winding, the said modifying winding is divided into two equal parts, the induced winding acting differenis preferably employed in practicing the invention. Flg. 4: is a sectional View on line aa ofFig.3. i ,i

' Like parts are indicated by similar charplcters of referencethropghout the different gures. L

While I have illustrated but twoembodiments of my invention, there may be many embodiments thereof, and -lldo not, therefore, wish to be limited to the two illustrated.

In each of Figs. 1 and 2 I have illus trated telephonesub-stations, 'A, B, but have j omitted the telephone] switclrhooks and other auxiliary apparatus thereat, as an illustration and description of such auxillary apparatus 1s not necessary to an understanding of my inventiom'nor 1s myinvention to be limited to the precise sub-station circuits illustrated. Ateach sub-sta-- tion there ,is shown a telephone transmitter 1 included in a local circuit that contains a battery 2 and a; primary 3} of, an induc- I tion coil in inductive relation with the secondary winding l of. comparatively many turns and included between the-sides 5-5 of the telephonic circuit, areceiver 6 at each station A being serially included in a conductorv 5. These sides 5may be conductivelycontinuous-or they may be inductively unitedj In 1 they are made conductively continuous, as, for example, by a cord circuit properly constructed. 2 they are'inductively united, though, as a matter of fact,. it is not necessary to provide a conductive or an inductive union be- 3 is a longi mal section of a un -polar generator that In Fig.

senses tween the sub-stations of'the. line, though in' the system illustrated in Fig. .2 this ispreferred, because the inducing winding -7 (hereinafter to be specified) may be com- 'mon'to theco'ils 8, that are in circuit with the receivers at stations A-B. .The element 8 is the induced winding of many turns, as compared with winding 7, and which has impressed thereupon the reinforced telephonic currentthat is to operate the telephone receiverat the receiving station. This reinforced telephonic current is impressed upon the windings through the agency of the inducing winding 7 that has current normally impressed thereupon of uniform. value, by the uni-polar generator,

r whlch 1s diagrammatically shown in Flgs. 1 and 2 and whose structure is Illustrated in.

Figs?) and 4. p

The field winding 10 that may be employed to produce the flux which is of uniform density, may be supplied with a. (2011- stant current from a battery 1-1, as indi- I cated in Fig. 1, orby being connected between the armature brushes 12-43, as indicated in Fig. 2, it being assumed in the armature has been brought to the proper speed to maintain the field winding 10, there shown in shunt, sufiiciently energized to produce the proper flux. In order that the curr'e'nt conditions in the coil 7 may normally be' constant, the armature or inductor 14 from which the generator current is supplied, is rotatedat' a very high uniform pe .ripheral velocity.

' The modifying winding 15 is serially related with the telephonic currents initially impressed, this modifying winding being equally -diwide d, so that the induced winding 8 will have difiereniial effect thereupon, and thereby upon the inducing'circuit, so that the said winding 15 is limited to the influence of the telephonic current led thereto from the transmitting stations In. the system shown in 'Fig. l the winding 15 is'looped in the conductor between the tele phone stations. In the system shown in Fig. 2 the winding 15 is also in the circuit extending to the transmitting station, I

though the circuit between the stations of Fig. 2' is' not conductively continuous.

The influence of the coils 10 and 15 and the structural characteristics of "the premore readily understood by reference to Figs. 3 and 4, wherein a base of non-magnetic metal 16 affords a bearing for the shaft 17 of the armature 14 andalso a. support for the field shell of the generator, that de'sirablyis made up of two sections 18-1- 9 separably connected, the section 18 being desirably-scparablyunited with the standard 16 for the purpose of easy assemblage of the parts and access to the windings of the 'gcncase of the system shown in Fig. 2 that uie ferred form of uni-polar generator willbe eenoae orator. The portion of the "frame or standard 16 that directly engages the section 18, is desirably ring-shaped and threaded to engage a correspondingly threaded shoulder upon the section 18. The armature ll; is preferably, though not necessarily, of cupshape and is desirably made of wrought iron of very high permeability in order to lessen the reluctance of the magnetic circuit, which magnetic circuit includes the sections 1S--l$ of the field shell, which sections are pret erably made of the same material and here constitute a tubular magnet. The reluctance due to the space between the sections 18-19 in which the armature 1-t rotates, is made as small as possible, to which end, the

air gaps between the armature and the pole faces of the sections 18-19 are made as small as practicable, whereby the reluctance of the magnetic circuit (indicated by a dot and dash line in Fig. 3) is maintained at a minimum.

The shell section 19 is provided with a central projection extending toward 'the armatuie,.while the shell section 18 is pro vided with a recess that is closed by said projection to constitutean annular space in which the field windings l0 and 15 are disposed, the winding 10 being of fewer turns preferably than the winding 15, particularly if this winding 10 is in shunt of the brushes or terminals of the machine. One brush of the machine is desirably in the formof a frictionless metal ring :20 that is slotted at 21 to prevent eddy currents, which ring is insulated from, though supported by, the centralprojection or core portion of, the element 19. This ring engages the inner peripheral edge of the armature 14:, which engagement is desirably maintained by means of light springs 22. The ring 20 is thus stationarily mounted and a series of taps 23 are taken therefrom and are joined together with one conductor extending to one end of the winding 7. The

other brush collecting current from the ar mature' let, is desirably the elongated bearingfor the shaft 17, which may be equipped with a binding post 24, so that a conductor may be connected with the other side of thewinding 7. The armature may be driven in any suitable way, preferably of a safe limiting velocity, a driving belt 25 running at suitable velocity, being indicated for the purpose.

A constant field, and thereby a uniform density of flux through the cylindrical portion of the armature 14, is maintained by the winding 10. This density of flux is increa d or diminished through the agency of the fluctuating voice currents passing through the winding 15, whereby the volume and pressure of the currei'it impressed upon the winding 7 is variable whenever the said winding 15 is subject to telephonic current,

which current is impressed upon the winding 8 that may be stepped up sulliciently so that the telephonic current received at the relay I have herein disclosed, may be suitably reinforced. -The location of the relay, where one only is employed, is preferably midway between the telephone sub-stations. It will he observed that the circuit of the modi tying winding 15 is brought into inductive relation with the circuit of winding 7.

While I employ an exciting winding 10 or magnetizing the sections 18--1) of the generator, I do not wish to be limited to such a way of magnetizing these parts of the generator, as it is obvious that they may be permanently magnetized, in which event the winding 10 will be dispensed with. The mechanical structure of such a device with the winding l0 eliminated may be exactly that illustrated. The iron, of course, is in the lorm of hard steel to retain its magnetism.

in Figs. 1 and 2 are shown two types of single telephonic circuits uniting telephone stations, the circuit in Fig. 1 being comluctively continuous at the exchange, while in Fig. 2 the sections of the telephonic circuit are inductively united. It is obvious, therefore, that a variety of arrangements may -.be provided for eli'ecting single telephonic circuits between the telephone stations, and I do not, therefore, wish to be limited to either of the two ways shown,

and in the claims I use the expression t single telephonic circuit in this broad sense.

In the claims I refer to the inducing winding as the primary and the induced winding as the secondary.

Reference may be had to my (re-pending application Serial No. 509,249, filed July 24-, 190%).

It is obvious that many changes may be made in the embodiments of the invention disclosed, without departing from the s irit of my invention, and I do not, there ore, wish to be limited to the precise arrangement and apparatus illustrated, but.

Having thus described my invention. I claim as new and desire to secure by Letters- ].al:e11t

l. A. system of telephony, including two telephone stations in a single telephonic circuit, a generator for propagating telephonic currents passing between the stations, said generator includin an element producing a magnetic field or flux, a winding subject to telephonic currentmodi't'ying the effect of the said .flux, an armature or inductor in the said flux. a primary supplied with current from said armature or inductor, and a secondary serving to step up the pressure of the current supplied thereto by the primary and to impress the trai'islormel current of iiu-reascd pressure upon the telephonic circuit, the generator having a two part winding, with respect to which the induced current in said secondary acts differentially.

2. A system of telephony, including two. telephone stations in a single telephonic cir-' cuit, a generator for propagating telephonic currents passing between the stations, said generator including an element producing a uniform magnetic field or flux, a winding subject to telephonic current modifying the effect of the said flux, an armature or inductor in the said flux, a primary supplied with current from said/armature or inductor,

and a secondary serving to step up the pressure of the current supplied thereto by the primary and to impress the transformed current of increased pressure upon the telephonic circuit, the generator having a two part winding, with respect to which the in duced current in said secondary acts differentially. j 5 r M, 3.Ajsystemoftelephony, including two telephone stations in a single telephonic circuit, a uni-polar generator for-propagating telephonic currents passing between the sta tions, a winding subject to telephonic 'cur-I rent modifying the effect of'the normal flux of the generator, a primary supplied'with current by the armature or inductor ;of the a generator, and a secondary serving td step upthe pressure of the current supplied there to by the primary and to impress the trans formed current of increased pressure upon the telephonic circult, the generator having a two part winding, withrespect to which .the induced-current-in said' secondary acts difi'erentially. v i

4. A system of telephony, including two telephone stations in a single telephonic circuit, a uni-polar generator-for propagating telephonic currents passing between the stations, a winding subject to telephonic current modifying the effect of the normal flux 'of the generator, at primary supplied with 5 ling ,di

current by the armature .or inductor of the generator, and a secondary.serving to step up the pressure of the current supplied thereto by the primary and to impress the trans formed current of increasedpressure upon the telephonic circuit, said secondary being,- 9

connected in bridge or multiple between the sides of the telephonic circuit.

5. A system of telephony, including two telephone stations in a single telephonic circuit, a uni-polar generator for propagating telephonic currents passing. between the sta- ,tions, a winding subject to telephonic cur-- of the primary, said secondary being connectedin bridge or multiple between the sides of the telephonic circuit.

6; A systemof telephony, includingtwop telephone stations in'a single telephonic circuit, a uni-polar generator for propagating telephonic currents and serving to produce,

current of substantially uniform volume and pressure, a winding subject to telephonic current modifying the effect of the normal flux of the generator, a primary supplied with current by the armature or inductor of the generator, and a secondary serving to step up the pressureof the current supplied .ther'eto -by. the primary and to impress the transformed. current ,of increased pressure upon the telephonic circuit, the generator having a two part winding, with respect to which the induced current in-said secondary acts differentially. i

7. A system of cuit, a uni-polar generator for propagating telephonic currents and serving to produce current ,.of substantially uniform volume and pressure, a' winding subject to .telephonic current modifying the effect of the normal transformed current of'increased pressure 'upon the telephonic circuit, said secondary being connected in bridge or multiple -be-' 'tween'the sides of the telephonic circuit.

8. A system of telephony, including two telephone stations in a single telephonic circuit, a uni-polargenerator for propagating telephonic currentsand serving-to produce current of substantially uniform volume and pressure, a winding subject to telephonic- .current modifying the effectof the normal 'fiux'of the generator, aprimary supplied with current by the armature or inductor of the generator, and a secondaryserving to step up the pressure of the current supplied thereto by the primary and to impress the transformed currentof increased pressure upon the telephonic circuit, the said secondary being dilferentially associated with the circuit of the primary, said secondary being connected in bridge or multiple between the sides of the telephonic circuit.

9; A system of telephony, including two telephone stations in a. single telephonic circuit, a generator for propagating telephonic currents passing betweenthe stations, sa1d generator including an element producing a magnetic field or flux, a windmg sub ect to telephonic'current modifying the effect of the said fiuX, an armature or inductor in the said. flux, a primary supplied with current from said armature or inductor, and

a secondary serving to step up the pressure I telephony, including two telephone stations in a'single telephonic cirflux of the generator, a primary supplied with current by the armature or inductor of the generator, and a secondary serving to step up the pressure of the current supplied thereto by the primaryand to impress the of the current supplied thereto by the primary and to impress the transformed current of increased pressure upon the telephonic circuit, the said modifying winding being in two parts with respect to which the induced current in the secondary acts difl'erentially.

10. A system of telephony, including two telephone stations in a single telephonic circuit, a generator for propagating telephonic currents passing between the stations, said generator including an element producing a uniform magnetic field or flux, a winding sub ect to telephonic current modifying the effect of the said flux, an armature or inductor in the said flux, a primary supplied with current from said armature or inductor, and a secondary serving to step up the pressure of the current supplied thereto by the primary and to impress the transformed current of increased pressure upon the telephonic circuit, the said modifying winding being in two parts with respect to which the induced current in the secondary acts differ entially 11. A system of telephony, including two telephone stations in a single telephonic circuit, a. uni-polar generator for propagating telephonic currents passing between the sta tions, a winding subject to telephonic current modifying the effect of the normal flux of the generator, a primary supplied with cur-' rent by the armature or inductor of the generator, and a secondary serving to step up the pressure of the current supplied thereto by the primary and to impress the transformed currentof increased pressure upon the telephonic circuit, the said modifying winding bein in two parts, with respect to which the induced current inthe secondary acts differentially.

12. A system of telephony, including'two telephone stations in a single telephonic circuit, a unipolar generator for propagating telephonic currents and servingto produce current of substantially uniform volume and pressure, a winding subject to telephonic current modifying the edect of the normal flux of the generator, a primary supplied with current by'the armature or inductor of the generator, and a secondary serving to step up the pressure of the current supplied thereto by the primary and to impress the transformed current of increased pressure upon the telephonic circuit, the said modifying winding being in two-parts, with respect to which the induced current in the secondary acts differentially.

13. A system of telephon including two telephone stations in a sing e telephonic circuit, a generator for propagating telephonic currents passing between the stations, said generator including an element producing a magnetic field or flux, a winding serially related to the telephonic circuit for modifying currents passing between the stations, said generator including an element producing a magnetic field or flux, a winding serially related to the telephonic circuit for modifying the effect of the said flux and divided into two parts, an armature or inductor in the said flux, a primary supplied with current from said armature or inductor, and a secondary in bridge of the telephonic circuit, one terminal of said secondary being connected between the parts of the modifying winding and the other with the opposite side of the telephonic circuit, said secondary serving to step up the pressure of the current supplied thereto by the primary.

15. A system of telephony, including two telephone stations in a single telephonic circuit, a generator for propagating telephonic currents passing between the stations, said generator including an element producing a magnetic field or flux,--a winding subject to telephonic current for modifying the effect of the said flux and divided into two parts, an armature or inductor in the said flux, a primary supplied with current. from said' armature or inductor, and a secondary for impressing reinforced telephonic current upon the telephonic circuit, the induced currents in the secondary acting differentially with respect to the parts of the aforesaid modifying winding.

16. Asystem of telephony, including two telephone stations in a single telephonic eir cuit, a generator for propagating telephonic currents passing between the stations, said. generator including an element producing a magnetic field or flux, a winding subjectto telephonic current for modifying the effect of. the said flux and divided into two parts, an armature or inductor in the said flux, a primary supplied with current from said armature or inductor, and a secondary for impressing reinforced telephonic current upon the telephonic circuit, the induced currents in the secondary acting differentially with respect to the parts of the aforesaid modifying winding, said secondary serving to step up the pressure of the current supplied thereto by the primary.

17. A system of telephony including two telephone stations in a single telephonic cir cuit, a. generator for propagating telephonic currents passing between the station. said generator includin an element producing a magnetic field or ux, a Winding subject to telephonic current passing from the stations in either direction over said single telephone circuit modifying the effect of the said flux, an-armature or inductor in the said flux, an

inducing Winding supplied With current press the transformed current of increased from said armature or inductor, and an induced Winding serving to step up the pres-1 sure of the current supplied thereto by the inducing winding andito impress the transformed current of increased pressure upon the telephonic circuit.

18. A systemof telephony including two telephone stations in a single telephonic circuit, a generator for propagating telephonic currents passing between. the stations, said generator-including. an element 'oducing a uniform magnetic field or flux, a Winding subject to telephonic current passing from the stations in either directionover said single telephonic circuit modifying the effect of the said flux, an armature or inductor in the said flux, an inducing winding supplied with current from said armature or inductor, and aninduced Winding servingito step up the pressure of the currentsupplied theretoby the inducing winding and toin pressure upon the telephonic circuit. 1

19. A system of telephony including tWo telephone stations in a singleitelephonic cire 'cuit, auni-polar generator for propagating telephonic currents passing between the stathe-generator, and an induced Winding serving to step up the pressure of the current i supplied tl'ieret'o by ,the inducing Winding tions, a Winding subject to telephoniccurrent passing from the stations in either directio1 i; over' said single telephonic circuit odifying the effect of the normal flux of he generator, an inducing inding supplied With current by' the armature or inductor of and to impress the transformed current of increased pressure upon the telephonic circuit.

20. A system of telephony including .tWo telephone stations in a single telephonic circuit, a uni-polar generator for propagating telephonic ,currents and serving to produce current of substantially uniform volume and pressure, a Winding subject to telephonic current passing'froni the stations in either direction over said single telephonic circuit modifying the efi'ect of the normal flux of the generator an inducing Winding supplied with current by the armature or inductor of the generator, and an induced Winding servtelephone stations in a single telephonic circuit a generator forpropagating telephonic currents passing, between the stations, said generator including a modifying inding subject to the telephonic current passing from the stations in either direction over said single telephonic circuit and a transformer whose. primary receives current from the armature of the generator and Whose,

secondary impresses the current received from the primary, upon the telephonic ciruit.

i 22. A systein of telephony' including two telephone stations in asingle telephonic circuit, a generator for propagating telephonic currents passing between the stat ons, said generator 1IlClI1d1Ilg a modifying Winding subject to the telephonic current passing from v the stations, in either direction over sai single telephonic circuit and a transformer whose primary rece ves current from the armature of the generator 'fiIld-WhOSG secr ondary impresses the current received from said secondary serving to' impressthetransformed current upon the telephonic. circuit at increased pressure.

v the priinary upon the telephonic circuit, the l 23. A system of telephony including two I telephone stations in a single telephonic cirv cuit, a uni-polar generator for -pi'opa atingw telephonic currents passing between t e Stations, said uni-polar generator includ'ing;a""-' modifying Winding subject tovthe telephonic I current'passing from the stations inaeither-i direction over said single telephonic circuit,

and means whereby the current lproduced by the uni-polar. generator may be' impressed upon the telephonic circuit.

24. A systemof telephony including .tivo

telephone stations in a single telephonic cir-v cuit, a uni-polar generator'for propagatingtelephonic currents passing between the stations, said uni-polar generatorincluding a modifying Windingsubj ect to the telephonic current passing from the stations in-either direction over said single telephonic circuit, and a transformer hose primary receives current-from the armature of the uni-polar generator and Whose secondary impresses the current received from the primary upon the telephonic circuit.- t i 25. A- system of telephony including tvvo telephonestations in a single telephonic cir cuit, a uni-polar generator'for'propagating telephonic currents passing between the stations, sald uni-polar generator including a modifying Winding subject to the telephonic current passing from the stations in either directlon over said single telephonic circuit,

and a transformer Whose primary receives current from the armati'u'e of the uni-polar. generator and Whose secondary impresses "the current received from the primary upon the telephonic circuit, the said secondary ceived from the -whose secondary impresses the current reserving to impress the transformed current upon the telephonic circuit at increased pressure.

2G.- A system of telephony including two telephone stations in a single telephonic circuit, argenerator for propagating telephonic currents passing between the stations, the generator, when not operating in conjunction with the modifying winding, serving to produce uni-directional current ()flllllfOl'll] value, said generator including a modifying winding subject to the telephonic current passing from the stations in either direction over said single telephonic circuit,and means whereby the current produced by the generator may be impressed upon the. telephonic circuit.

27. A system of telephony including two telephone stations in a single telephonic circuit, a generator for propagating telephonic currents passing between the stations, the generator, when not operating in conjunction with the modifying winding, serving to produce uni-directional current of uniform value, said generator including a modifying winding subject to the telephonic cnrrcnt passing from the stations in either direction over said single telephonic circuit, and a transformer whose primary receives current from the armature of the generator and whose secondary impresses the current rcprimary upon the telephonic circuit.

- 28. A system of telephony including two telephone stations in a single telephonic circuit, a generator for propagating telephonic currents passing between the stations, the generator, when not operating in conjunction with the modifying winding, serving to produce uni-directional current of uniform value, said generator including a modifying winding subject to, the telephonic current passing from the stliti ms in either direction over said single telephonic circuit,.and a transformer whose primary receives current from the armature of the generator and ceived from the primary upon the telephonic circuit, the said secondary Serving to impress the transformed current upon the telephonic circuit at increased pressure.

.29. A system of telephony including two telephone stations in a single telephonic circuit, a generator of current having added thereto a modifying winding subject to telephonic current passing from the stations. in either direction over said single telephonic circuit, and means whereby the current of the generator is impressed upon the telephonic circuit.

' 30. A systemof telephony including two ing said magnetic field by inductive effect of telephonic currents emanating from either of the stations of said single telephonic circuit; an inductor moving in said magnetic field producing a current corresponding to the modified flux density of said magnetic field, means for increasing the pressure of the thus modified current, and impressing same upon said telephonic circuit.

32. A system of. telephony, including two telephone stations on a single telephonic circuit, a generator for propagating telephonic currents emanating from either station of said single telephone circuit; an element included in said generator producing a magnetic field of uniform flux density; a wind ing, subject to said telephonic currents, and producing a modifying effect of said magnetic field; an inductor in said magnetic field, a primary winding supplied with current from said inductor and a secondary winding, serving to increase the pressure of the current supplied by said primary winding, andto impress the amplified and trans formed current upon the telephonic circuit. 33. In a system of telephony, a device for propagating telephonic currents'emanating from either station of a single telephone circuit, comprising a generating element; an element included in said generating element, serving to produce a constant magnetic field; a means for subjecting said constant magnetic field to inductive action of telephonic currents emanating from said stations of said single telephone circuit, and a means for transforming the resultant current, produced by action of said generator and the modifying effect of said telephonic currents, and impressirigsame upon said telephonic circuit.

Signed by me at Chicago, county of Cool: and State oflllinois this fifteenth day of July, 1909:

CHARLES G. ASHLEY. \Vitnesses i IJAVID S. HULF'ISII, HAnRin'r L. SMITH.

Copies- 0f this patent may be obtained for five cents each, by addressing the "Commissioner of Ifatents.

Washington, D. C.

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