US1758450A - Regulator - Google Patents

Description

EXAMINER AU 252 Ex lss REFERENCE FIP8Z1Z May 13, 1930.

G. F. MACHLET REGULATOR 2 Sheets-Sheet 1 Filed June 18 1926 Further Amplification EXAMINER E C uh E D E F E D S S 0 R u.

May 13, 1930. G. F. MACHLET REGULATOR Filed June 18. 1926 2 Sheets-Sheet 2 In uenfo/c' 6 Patented May 13, 1930 UNITED. sures PATENT OFFICE Application filed June 18,

This invention relates to means for regulating the heat of furnaces, such as shown, for example, in my Patents No. 1,068,065, of July 22, 1913; No. 1,099,658, of June 9, 1914, and No. 1,306,015, of June 10, 1919, and for regulating power and other apparatus, as, for example, electric circuits, and for other purposes, especially where delicate action is involved.

In heat regulators, there has usually been employed a galvanometer, which is affected by variations in the heat of a furnace. In other cases regulation has been eflected by variations in the strength of the electric current which is to be controlled, or by variations in the output of power.. The galvanometer, voltmeter or other electric 'measuring device usually includes a delicate needle, whereby it has been sought to secure a very close regulation, as, for example, it has been the practice to maintain a furnace at say 2000 degrees, without-a variation of more than five or ten degrees of heat.

In certain of said patents, and in my Patent N 0. 1,227,921, of May 29, 1917, mechanicallyoperating devices have been made to co-operate with the galvanometer or voltmeter needle, in such a manner that the needle would act as a mechanical interponent in the 39 mechanism. A feature of the present invention is that the movement .of the needle is absolutely unobstructed, and the necessity for intricate mechanism is avoided, while the regulation is rendered very fine, even under extreme heat or other extreme conditions. The

device is inexpensive, and is readily connected to the voltmeter, galvanometer or other needle device, as well as to the furnace or other apparatus to be regulated.

To secure these and other ends, a selenium tube or bulb, or a photo-electric cell, or lightsensitive cell, is'exposed to light from any suitable source, this light-sensitive cell being included in an electric circuit, in which the power of the electric current is dependent upon theefl'ect of the li ht upon the sensitive cell, as is understood. be light of the lamp, which may be an electric-bulb is concentrated 'prefe ably by the means of a convex oblong lens, and directed through a slitnnto the sen- 1928. Serial Io. 118,801.

sitive cell. The needle of the galvanometer advances to and over this slit as the heat of the furnace rises, or as a fluctuation occurs in an electric powersystem or other apparatus.

Thus the light is diminished or shut off from the sensitive cell, and hence there is weakening of the current in the circuit which includes said cell.

This fluctuation in the circuit of the lightsensitive cell is utilized to vary the supply of fuel to the furnace, or to vary the strength of the electric current in a system which is to be controlled, or to effect such other regulation or change as may be required.

Preferably the regulation is effected in proportion to the fluctuation of heat and during such fluctuation. The regulator preferably does not turn the fuel supply wholly on or wholly off, but rather affects the rate of fuel supply in proportion to the intensity of the light falling upon the sensitive cell. The invention has in its preferred form the advantage of reducing or increasin the rate of supply of fuel in proportion to Fhe requirements of the furnace, the flow of fuel being uninterrupted, but being diminished or augmented. The temperature of the furnace advances slowly, the shutter slowly diminishes the light effect upon the sensitive cell,'the galvanometer comes to rest at a goint where the light is only partially obscure by the shutter, and the supply of fuel is slowly and evenly reduced. There may thus be brought about a balance, the supply of fuel being automatically held at a point where the furnace heat will neither decrease nor increase.

Preferably a special resistance amplifier, such as is commonlv used, for example, with photo-electrical cells, is introduced in the in a way to permit rotative adjustment of the cell and frame about the axis of movement of the galvanometer needle, so that the regulation of the furnace may be set to take place at any desired point. The electric lamp may be mounted upon the same frame, so as to be adjusted to ether with the cell. The shutter portion 0 the needle may radiate from the galvanometer pivot, and may extend oppositely'from the needle itself; and it may be of a width to cut off the light from the sensitive cell long enough for increasing the heat of the furnace to be checked, and in case it is rapidly increasing at an time.

Other features and a vantages will hereinafter appear.

In t e accompanying diagrams.

Figure 1 is a alvanometer with an adjustable selenium or ight-sensitive cell frame, this view showing also a furnace which is included in the circuit of the galvanometer needle and which has a fuel supply which is included in the circuit of the lig t-sensitive cell, there being also included in the selenium circuit an am lifier.

igure 2 is an elevation, artly in section, of the galvanometer and t e light-sensitive cell and its housin adjustable thereon, showing also the electric light bulb.

Figure 3 shows a voltmeter forming part of an electric current regulator.

Into the flame-chamber of a furnace 10, whose heat is to be regulated, extends a fire end 11, connected by wires 12, 13, to a rotative coil or element 14 of a galvanometer 15 as usual, the element 14 being pivoted as indicated at 16, and having a needle 17 extending over the usual scale 18, whereby may be ascertained the heat of the furnace 10.

According to the present invention, the element 14, by its rotation, is also utilized to control the heat of the furnace. For this purpose a shutter-arm 19 radiates from said pivot 16, preferably in the opposite direction rom the needle 17, and preferably formed in one piece with said needle. The use of this shutter-arm is to intercept all or part of the light, which is caused to fall from an electric lamp 20 upon a selenium, photo-electric, or other li ht-sensitive cell, tube, or bulb 21. This lig t-sensitive cell 21 is within a dark housing 22, having along its top a narrow slit 23, permitting light to enter from the lamp 20. An oblong lens or light-focusing device 24 above said slit serves to concentrate the light from the lamp 20 and increase the efficiency of the apparatus. The shutter 19-may swing freely in the space between the lens and the slit 23, the boxwork of the wall of the galvanometer 15 having a horizontal slot 25 to permit this motion, and an open or clear space being left at 26 above the housing 22, for the same purpose. While the furnace is heating up and the needle 17 and the shutter 19 are swinging, the light from the lamp a) shines same circuit is a battery or source of ower 29 and an amplifier, which is general y designated as A; the amplifier being of a construction usual in radio-receivin sets and in other arts, being usually in the form of the wellknown tube. From the battery 29 a conductor 30 of said circuit extends to a solenoid 31, and from the latter there extends a return conductor 32 to the amplifier A, the effectof the amplifier being to augment the power of the solenoid 31. By the rising and falling of the core 33 of said solenoid, the supply of fuel to the furnace 10 is regulated.

The fuel usually consists of gas from a main 34 and compressed air from a main 35, which enter a mixer, designated as M, from which the mixed fuel is delivered through a pipe 36 to a manifold 37, from which extend burners 38 into the frame-chamber of the furnace 10. In the mixer are various ports which are opened and closed by means of poppet-valves 39 mounted upon a common stem 40, the lower end of which is joined to a bellows-like drum 41, which is in the form of a thin-walled copper cylindrical box having peripheral corrugations or pleats which permit the drum to lengthen and shorten according to the variation in air pressure therein, the air entering from a tube 42. Increase of pressure causes the drum or diaphragm 41 to expand and thereby lift the stem 40 and the oppet-valves, while a decrease in pressure as the opposite effect, closing the ports.

From the compressed air main 35 extends a nozzle 43 into which .0 ens the end of the diaphragm tube 42; an a needle or other valve 44 may .be provided in said nozzle between the tube 42 and the main 35, to control manually the pressure of air in the tube 42 and in the diaphragm 41. The nozzle is also provided with an outlet 45, forming a continuing leak, which is reducible by a stem or closure 46 extending up from the solenoid core 33,

From the foregoing it will, be understood that when the shutter 19 of the galvanometer partially closes the slit 23 and thereby partly shuts off the light-sensitive cell 21 from receiving light, the electric current in the circuit of said cell is weakened accordingly, and hence the power of the solenoid 31 is reduced, an the core 33 drops more or less.

thereby opening more or less the leak 45 and permitting waste of compressed air from the nozzle 43, whereby, the pressure in the tube 42 is reduced, as well as in the drum or' diaphragm 41, which contracts, so that its stem 40 descends, together with all of the pop etvalves 39, and the supptliy of fuel to the urnace is reduced or cut 0 Upon the heat of the furnace falling, the galvanometer is affected accordingly, and the shutter 19 rotates, thereby uncovering more of the slit 23, and affecting the light-sensitive cell circuit accordingly, and increasing the power of the solenoid 31, whereby the core 33 is lifted and the leakage at is reduced, and the pressure in the tube 42 and diaphragm 41 is raised accordingly, and the valves 39 hence are opened and the supply of fuel to the furnace is increased.

It will be noted that there is entire absence of any obstruction or opposition to the movement of the needle 17 or shutter 19, so that the same may be extremely sensitive in operation and yet positively control the heating of the furnace in a simple manner. The control is quickly efiected, and a furnace may be maintained at heat of thousands of degrees with negligible fluctuation. The shutter by only partially closing the slit 23 may effect sufficient weakening of the current in the selenium cell circuit as to barely open the leak 45, and permit an almost imperceptible constant or continuous waste of air from the nozzle 43, but still sufiieient to keep theair pressure in 42 and 41 at the exact pointfor supplying just enough fuel to maintain the heat of the furnace at that point substantially v without any variation; the entire apparatus being very sensitive, while at the same time eflicient to control the furnace.

For using the device at difi erent de rees of heat, an adjustment is provided. A racket or frame 47 is pivoted upon a shoulder 48 of a 'stud 49, rising from the top of the casing of the ga-lvanometer 15, said bracket carrying at one end a bent arm 50 supporting the electric-light bulb 20, and carrying at its other end the housing 22 of the selenium cell, whereby the bracket, the housing and the light may be adjusted as a unit concentrically with the rotary element 14 of the alvanometer, a thumb-nut 51 being threade upon the stud 49 to secure the parts where adjusted. The adjustment may be aided by means of an index 52 carried upon the bracket and co-operative with the usual scale 18 of the galvanometer.

The amplifier unit is of well-known construction, and, may include an l8 -volt bat tery 53, a grid leak 54, a 6-volt battery 55 and the usual tube 56. The invention is not limited to the use of an amplifier in the same circuit with the light-sensitive cell and the solenoid, for the invention includes broadly 'cRoss REFERENCE nometer may be utilized in reglililating other apparatuses or elements than rnaces.

At Figure 3 a voltmeter 57 is connected to the power mains 58, 59, leading from a dynamo 60. The voltmeter is provided with the shutter-arm 19, to cover a light slit 23 over a light-sensitive cell 21, as in the other views, the circuit of the sensitive cell including wires 27, 28,- amplifier A, battery 29 and wires 30, 32, the latter leading to and from a magnet 61. By means of thls magnet and its pivoted armature 62, there is kept closed or nearly closed a jet63, similar to 43, from which compressed air leaks; this jet or nozzle leading from a ipe 64, in which air is kept under pressure y a pump or blower 65. Also connected to pipe 64 is a large expansible drum 66, corresponding with 41, which is maintained in expanded condition by the compressed air therein. To the top of the drum is pivoted a switch-arm 67, operating upon rheostat 68 included in said main circuit 58, 59. When the current in the dynamo circuit is below normal, the light slit 23 remains open, and a strong current is maintained in the sensitive-cell circuit, and the maglnet 61 keeps the leak 63 practically closed, so t at there is high air pressure in the drum or diaphragm 66, and. the switch-arm 67 is kept at its upper position, cutting out much of the resistance 68. When the current in the dynamo circuit increases to the desired point, the slit 23 is wholly or partially covered by the shutter 19, and through the described train the air pressure in the drum 66 is weakened, and it collapses to a certain extent, lowering the switch-arm 67 and thereby cutting more resistance into the dynamo circuit.

Variations may be resorted to within the scope of the invention, and portions of the im rovements ma be used without others.

aving thus escribed my invention, I claim:

1. The combination with an element or apparatus subject to fluctuations, of means includin a galvanometer or the like includin a iutter movable by fluctuations in the ga vanometer' circuit, a light-sensitive cell, a housin therefor having a 1i ht-receiving slit closa le by said shutter, an means controlled hy said light-sensitive cell for regulating said element or apparatus, said regulating means including a coil in circuit with EXAMINER said lightsensitive cell, an amplifier in the same circuit with said coil and cell, and a regulating device having an independent source of power and including a controller for said power operated by said coil.

2. The combination with an element or apparatus subject to fluctuations, of means including a galvanometer or the like including a shutter movable by fluctations in the ga vanometer circuit, a light-sensitive cell, a housing therefor having a light-receiving slit closable by said shutter, a coil in circuit with said cell, and means controlled by said lightsensitive cell through said coil for regulating said element or apparatus, said cell-circuit including a step-up device whereby weak variations in current caused by the effect of the galvanometer shutter upon the lightsensitive cell effect strong variations in current in said coil, an independent source of power under control of said coil, and means to enable said source of power to regulate said apparatus.

3. In combination, a galvanometer having a movable shutter-arm, a photo-electric cell, a housing therefor having a slit, a lamp mounted to shine through said slit upon said cell, said slit closable by said shutter-arm, the advancing shutter covering or obscuring the slit in proportion to its advance, and diminishing the conductivity of the photo-electric cell in proportion as the light is obscured by said shutter-arm, an amplifying device in circuit with said cell, and an independent source of power through which said cell-circuit is connected to operate a regulator for heat,-

power or electricity, said independent source of power being controlled by a device in said cell-circuit.

4. In combination, a galvanometer having a movable shutter-arm, a photoelectric cell, a housing therefor having a slit, a lamp mounted to shine throu h said slit upon said cell, said slit closablc y said shutter-arm, the advancing shutter covering or obscuring the slit in proportion to its advance, and diminishing the conductivity of the photo-electric cell in proportion as the light is obscured by said shutter-arm, an amplifying device in circuit with said cell, said amplifier being included in the same circuit with said photoelectric cell, and an electrically-operated regulator controlled by said circuit and having means to regulate heat, power or electricity.

5. In combination, a galvanometer having a movable shutter-arm, a photo-electric cell, a housing therefor having a slit, and a lamp mounted to shine throu h said slit'up'on said cell, said slit closable y said shutter-arm,

said housing and cell carried upon a frame which is adjustably mounted to permit said shutter-arm to effect regulation at different selected points in the movement of the galvanometer shutter-arm.

6. In combination, a galvanometer having a movable shutter-arm, a photo-electric cell, a housing therefor having a slit, a lamp mounted to shine throu h said slit upon said cell said slit closable by said shutter-arm, said housing and cell carried upon a frame which is adjustably mounted to permit said shutter-arm to effect regulation at different selected points in the movement of the galvanometer shutter-arm, said galvanometer having a scale, and an index to co-operate there with in setting the adjustable device.

7. In combination, a galvanometer having a movable shutter-arm, a photo-electric cell, a housing therefor having a slit, a lamg mounted to shine through said slit upon sai cell, said slit closable by said shutter-arm, said housin and cell carried upon a frame which is ad ustably mounted to permit said shutter-arm to effect regulation at different selected points in the movement of the galvanometer shutter-arm, said galvanometer having a scale, an index to co-operate therewith in setting the adjustable device, and a lamp mounted upon said adjustable frame to shine through said slit upon said cell.

8. The combination of a galvanometer circuit including a part affected by the condition of a generator to be regulated, and which sets up a current in said circuit, said galvanometer having a movable shutter affected by the strength of the current, a light-sensitive cell, a housing therefor having an opening for the reception of light, said shutter mounted to be capable of closing said opening, a lamp to shine through said opening upon said cell, said light-sensitive cell being included in a circuit having a battery or other source of power and also having an am lifier inclusive of an amplifier tube, a coil, included in the same circuit with said amplifier and said cell, and a generator-regulating device controlled by saia coil.

9. The combination of a galvanometer circuit including a part afi'ected by the condition of a generator to be regulated, and which sets up a current in said circuit, said galvanometer having a movable shutter affected by the strength of the current, a light-sensitive cell, a housing therefor havin an opening for the reception of li ht, said shutter mounted to be capable of'c osing said opening, a lamp to shine through 'said opening upon said cell, said light-sensitive cell being included in a circuit having a battery or other source of power and also having an amplifier inclusive of an amplifier tube, a coil included in the same circuit with said am lifier and said cell, a generator-regulating evice controlled by sald coil, said generator in the form of a furnace, means for supplying fuel to said furnace, and means controlled by said regulating coil for varying the supply of fuel-to the furnace,

10. Heatregulating nieans for a furnace,- including an expansi le drum or diaphragm :fikl'flblfi by com ressed air and controlling e supply of fue to said furnace, and a galvanometer circuit having a thermotic element affected by the fluctuations in the heat of the furnace, a shutter element operated by said alvanometer, a light-sensitive cell, a hous mg therefor having a slit which may be opened and closed by said galvanometer shutter, means for permitting the pressure of air in said drum or diaphragm to leak, and means controlled by said sensitive cell to close and open said leak.

11. The combination with an element or apparatus subject to fluctuations, of means including a galvanometer or the like including a shutter movable by fluctuations in the galvanometer circuit, a light-sensitive cell, a

housing therefor having a light-receiving slit closable by said shutter, means controlled by said light-sensitive cell for regulating said element or apparatus, said galvanometer having an adjustable frame or bracket pivoted thereonconcen'trically with the rotative dea vice of the galvanometer, said sensitive cell carried upon said frame for adjustment, a light bulb upon said frame, and an index to co-operate with said frame in adjusting the same.

12. A heat-controlling rheans for a furnace, said controlling means including a galvanometer circuit having a thermotic element aflected by the fluctuations in the heat of the furnace, a shutter-element operated more.or less by said galvanometer, according to fluctuations in the galvanometer circuit. an electrical controller including both a light-sensitive cell and a housing therefor having a slit which may be opened and closed bysaid galvanometer-shutter, the fluctuations of said electrical controller being dependent upon variations in the current in the light-sensitive cell-circuit effected by said shutter, and means governed by said electrical controller for determining the supply of fuel.

13. In a fuel-supply-regulating means for a gas furnace having a set of air. and gas mixing valves 'and also having a galvanometer circuit including a thermotic element afiected by the fluctuations in the heat of the furnace, the combination of a shutter operated by said galvanometer, a light-sensitive cell, a housing therefor having a light-opening closable by said shutter, a source of light to shine through saidopening upon said cell, said light-sensitive cell being included in a "second circuit having a source of power and also having an amplifier inclusive of an amplifier tube, a c011 being also included in said second circuit, a drum having a controlling stem joined to said valves, said drum formed of flexible metal and having circumferentially plated sides and expansible by air pressure, a connection from said drum to the supply of compressed air to said mixing valves, and means conoRoss REFERENCE trolled b said coil to vary the pressure of air in said rum.

14. The combination with a furnace havin a supply of gas and a supply of compressed air and a set of mixing and controlling valves, and also having a galvanometer circuit including a thermotic element affected by the fluctuations of heat in the furnace, of a shutter-element controlled by said galvanometer,

a light-sensitive cell, a source of light, a housing for said cell having a slit which may be opened and closed b said shutter, a solenoid in a circuit contro ed by said cell, a drum Y EXAMINER connected to operate said valves and having a connection from its interior to said supply of compressed air, said drum formed of flexible sheet-metal and having sides formed of be]- lows pleats, and being longitudinally expansible and contractible,-and means controlled by said solenoid to vary the pressure of air in said drum and thereby control its elongation or contraction for operating the valves.

15. The combination with a furnace having a supply of gas and a supply of comfirl'lessed air and a set of mixing and controlg valves, and also having a galvanometer circuit including a thermotic element affected by fluctuations of heat in the furnace, of a light-sensitive cell, a shutter-element operated by said thermotic element and controlling the lighting of said cell, a solenoid in a circuit controlled by said cell, an expansible sensitive cell, a shutter-element operated bysaid thermotic element and controlling the lighting of said cell, a solenoid in a circuit controlled by said cell, an expansible drum connected to operate said valves and having a connection from its interior to said supply of compressed air, said drum provided with a leak, and a closure for said leak controlled by said solenoid to va the pressure of air in said drum and there y control its expansion and contraction, for operating the valves. 17. The combination with a furnace having a supply of gas and a supply of comressed air and a set of mixing and controlng valves, and also having a galvanometer circuit including a thermotic element aifected by fluctuations of heat in the furnace, of a light-sensitive cell, a shutter-element operated by said thermotic element and controlling the lighting of said cell, a solenoid in a y said solenoid to of air in said drum and thereby control its e ansion and contraction, for operating the va ves, and a manually regulatable valve betvlveen said drum and said compressed air sup- P 18. The combination with a furnace having a supply of gas and a supply of compillessed air and a set of mixing and controlg valves, and also having a galvanometer circuit including a thermotic element afl'ected by fluctuations of heat in the furnace, of a light-sensitive cell, a shutter-element operated by said thermotic element and controlling the lighting of said cell, a solenoid in a circuit controlled by said cell, a drum formed of thin flexible sheet-metal and having sides formed of bellows pleats, and being longitudinally expansible and contractible to control.said valves, a separate connection between the interior of the drum and the comprressed air supply, and a nozzle extending om said compressed air supply, said nozzle having a leak, and said solenoid having a closure for said leak.

19. The combination of a heating apparatus to be regulated, a galvanometer controllable by said apparatus and affected by the heat thereof, and having a movable shutter, a light-sensitive cell dominated by said shutter, an electric circuit including said cell, a pneumatic device having a leak, magnetic means being included in said cell circuit for controlling said leak, and a regulator for said heating apparatus controlled by said pneumatic device. a,

20. In combination, with an apparatus to be regulated, a galvanometer circuit, the needle of which has a delicate shutter form and is sensitively movable by reason of fluctuations in the current, a light-sensitive cell dominated bysaid shutter, said shutter having a substantially great range of idle movement without dominating said cell, permitting the regulated apparatus to reach approximately the desired stage of efliciency before regulation begins, and a regulating circuit includmg said cell; whereby delicate regulation oflthe apparatus is secured in a short range of movement of the shutter around the point of desired efliciency of the apparatus.

21. In combination, with an apparatus to be regulated, a galvanometer circuit, the

ting the regulated apparatus toreach apneedle of which has a delicate. shutter form.

and is sensitively movable by reason of fluctuations in the current, a light-sensitive cell dominated by said shutter, said shutter having a substantially great range of idle movement without dominating said cell, permitfor said leak conroximately the desired stage of cficiency fore regulation begins, and a regulating circuit including said cell; said shutter and cell being mounted for relative adjustment, to predetermine the stage at which regulation shall begin.

22. The combination with a member to be regulated, of a pneumatic regulator having a continuously operating leak, an electric circuit having means for delicatel varying the rate of flow of air through sai leak and thereby controlling said regulator, and means for automatically varying the flow of current through said circuit.

23. The combination with a member to be regulated, of a pneumatic regulator having a continuously operating leak, an electric circuit having a light-sensitive cell and also having means for delicately varying the rate of flow of air through said leak, and means for automatically controlling the supply of light to said cell.

24. The combination with a member to be regulated, of a pneumatic regulator having a continuously operating leak, an electric circuit having a light-sensitive cell and also having means for delicately varyin the rate of flow of air through said leak, an a master electric circuit having a sensitively moving shutter dominating said cell.

25. The combination with a member to be regulated, of a pneumatic regulator having a continuously operating leak, an electric circuit having a light-sensitive cell and also having means for delicately varying the flow of air through said leak, and a master electric circuit having a sensitively moving shutter dominating said cell; means being provided for afiording a preadjustment between said shutter and said cell.

26. The combination with a re latable apparatus subject to fluctuations, o a lightsensitive cell, an enclosure therefor having an opening for the admission of light thereto, a shutter for said opening, said shutter sensitive to the fluctuations ,of said ap aratus, an electric circuit including said hg tsensitive cell, a pneumatic device including a diaphragm or pneumatic member having a continuously operating air leak, magnetic means in said circuit for delicately varying the rate of flow of said air leak and thereby controlling the movement of said diaphragm, and means under the control of said diaphragm for efiecting regulation of said apparatus.

27. The combination with a re atable apparatus subject to fluctuations, o a light- ,sensitive cell, an enclosure therefor having an opening for the admission of light thereto, a shutter for said opening, said shutter sensitive to the fluctuations of said apparatus, an electric circuit including said hghtsensitive cell, a pneumatic device including a diaphragm or pneumatic member having a continuously operating air leak, magnetic means in said circuit for delicately varying the rate of flow of said air leak and thereby controlling the movlnent of said diaphragm, and means under the control of said diaphragm for effecting regulation of said apparatus; means being provided for allording relative preadjustment between said opening and said shutter, for predetermining the point at which regulation of said apparatus shall take place. v

28. The combination with a regulatable apparatus subject to fluctuations, of an instrument whose movements are sensitively controlled by said fluctuations, a pneumatic device capable of effecting regulation of said apparatus, said pneumatic device having a continuously operating air leak, and means under the control of said sensitive instrument for delicately varying the rate of escape of air through said leakand thereby controlling the movements of said pneumatic device.

29. The combination with a regnlatable apparatus subject to fluctuations, of an instrumentwhose movements are sensitively controlled by said fluctuations, a pennmatic device capable of effecting regulation of said apparatus, said pneumatic device having a continuously operating air leak, and means under the control of said sensitive instrument for delicately varying the rate of escape of air through said leak and thereby controlling the movements of said pneumatic device, said leak-regulating means including a light-sensitive cell whose light supply is controlled by said sensitive instrument, and an electric circuit including said light-sensitive cell and a magnetic valve for said leak.

30. The combination with a regulatable apparatus subject to fluctuations, of an instrument whose movements are sensitively controlled by said fluctuations, a pneumatic device capable of effecting regulation of said apparatus, said pneumatic device having a continuously operating air leak, and means under the control of said sensitive instrument for delicately varying the rate of escape of air through said leak and thereby controlling the movements of said pneumatic device, said leak-regulating means including a li htsensitive cell whose light supply is controlled said sensitive instrument, and an electric circuit including said light-sensitive cell and a magnetic valve for said leak, said sensitive instrument mounted for oscillation, and said cell being mounted for adjustment around the center of said oscillation, to predetermine the point at which regulation shall take place.

31. The combination with an apparatus to be regulated, of an electric circuit including a needle whose movements are sensitively affected by fluctuations in said apparatus, a light-sensitive cell, said needle having a part moving therewith to control the supply of light to said cell, an electric circuit includin said celland also including a magnetically movable valve, and a pneumatic device having means to control said apparatus and also having a continuousl operating leak throu h which the flow of air is delicately varied by said valve.

32. The combination ofa heating apparatus, an electric circuit including a shutter sensitively affected by fluctuations in the heat of said apparatus, a light-sensitive cell dominated by said shutter, an electric circuit including said cell and a magnetic valve, and an air-pressure device controlling the heat of said apparatus and having a continuously operating leak through which the passage of air is delicately varied by said valve.

33. Heat regulating means for a furnace having a fuel-controlling means, said regulating means including a galvanometer circuit including a thermotic element afi'ected by the fluctuations in the heat of the furnace, a shutter element controlled by said galvanometer, a light-sensitive cell, a housing therefor having a slit which may be opened and closed by said shutter, a solenoid in a circuit controlled by said cell, and means to enable said solenoid to control the operation of said fuel-controlling means.

34. The combination of a galvanometer having a moving element, a circuit including said galvanometer, a shutter movable by the current in said circuit, a light-sensitive cell dominated by said shutter, an adjustable mount for .said cell upon said galvanometer affording adjustment of the cell along the path of the moving element of the galvanometer, an electric circuit including said cell and a regulating device controlled by. sai electric circuit.

GEORGE F. MACHLET.

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