US519338A - moelroy - Google Patents
moelroy Download PDFInfo
- Publication number
- US519338A US519338A US519338DA US519338A US 519338 A US519338 A US 519338A US 519338D A US519338D A US 519338DA US 519338 A US519338 A US 519338A
- Authority
- US
- United States
- Prior art keywords
- cylinder
- series
- plugs
- metallic
- heaters
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000010438 heat treatment Methods 0.000 description 10
- 239000011810 insulating material Substances 0.000 description 8
- 230000005611 electricity Effects 0.000 description 4
- 239000000126 substance Substances 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H19/00—Switches operated by an operating part which is rotatable about a longitudinal axis thereof and which is acted upon directly by a solid body external to the switch, e.g. by a hand
- H01H19/54—Switches operated by an operating part which is rotatable about a longitudinal axis thereof and which is acted upon directly by a solid body external to the switch, e.g. by a hand the operating part having at least five or an unspecified number of operative positions
- H01H19/56—Angularly-movable actuating part carrying contacts, e.g. drum switch
- H01H19/58—Angularly-movable actuating part carrying contacts, e.g. drum switch having only axial contact pressure, e.g. disc switch, wafer switch
Definitions
- My invention relates to improvements in mechanism for directing the current of electricity; and the object of my invention is to provide an electric switch particularly adapted for use in mechanism for heating with electricity. I accomplish this object by means of the mechanism illustrated in the accompanying drawings, in which- Figure 1 is a plan. Fig. 2 is an end elevation. Fig. 3 is a side elevation. Fig. 4 is a longitudinal section. Fig. 5 is a detail View showing the connections between the metallic plugs in the cylinder. Fig. 6 is an end elevation of the knob H. Fig. 7 is a seriesof cross sections of the cylinder showing the position of the metallic plugs therein, and Fig. 8 is a View of the wiring in the car.
- the cylinder X is composed of any suitable material and mounted upon a spindle d journaled Within the box G and has keyed to it at one end the knob H. At one end of the cylinder and secured thereto, I arrange the notched wheel W'. Before mounting the cylinder, I core out a series of passage ways extending in a path parallel to its axis; said passage ways usually extending from one end of the cylinder to the other. Within the passage Ways thus cored out of the cylinder, I place a series of metallic plugs 10 separated by an insulating substance Z; said plugs sometimes connected by metallic rods R in the manner hereinafter described.
- section A there are three plugs, (see Fig. 7) section B also contains three plugs; section C two, section D three; section E one and section F five.
- Fig. 5 the letters at the bottom of the figure refer to the sections and show by the number of squares in the upright column in full lines, the number of metallic plugs in each section.
- the figures at the right of Fig. 5 refer to the various series of metallic plugs in the section and show how they are connected.
- Figs. 1, 3, 4 and 7 the positions of the various plugs and numbered them according to which series they belong.
- series 1 at the top of the cylinder, is seen series 1; lower down is series 2, while the springs are in contact with series 8.
- Fig. 4 shows the connection of the plugs of the third series, in which the plug in section Ais connected with the plug in section D by means of the rod R separated by the insulating material Z. The plug in section E extends through into section F.
- I mount the rocking shaft J carrying a spiral springj and having pivoted to it the bell-crank lever'K.
- One end of the lever K is provided with a handle it; the opposite end carries the metallic disk K.
- One side of the arm of the lever which carries the disk K is provided with a stud Z constructed to engage with the openings L in the wheel Wwhen the disk K is between the posts M and N.
- the disk K is constructed to fit snugly between the metallic posts M and N; the posts M and N are insulated from the box and cylinder, as is also the disk K from the lever K.
- the post N is connected by wire to one pole of the battery; the postM is connected by wire to an electric finger F; said electric finger F being attached to an insulated bolt in the frame of the box at one end, itsother end being in contact with section F of the cylinder.
- the fingers E, D, C, B, and A are arranged in contact with the corresponding sections of the cylinder.
- the current passes from the battery to the postNthrough disk K to the post M and is carried to finger F (see Fig. 1) thence to the plug in sections E and F, thence through linger E to the resistance to be heated and returns to the finger E and plug in section D and is conducted to the plug in section A from thence it passes to the ground.
- the circuit is made or broken. hen the circuit is complete, the disk K being in position between the posts M and N, the cylinder is locked, the lug I within the wheel 1V prevents the oscillation of the cylinder, and in order to change the position of the cylinder and thereby operate the switch, it is necessary to first break the circuit by operating the lever.
- the numbers on the knob II shown in Fig. 6, indicate the position of the cylinder and after the lever is drawn back, the cylinder may be revolved by means of the knob to the position indicated by the figures and then the circuit may be made and the switch placed in operation.
- the heaters in the car are numbered 11, 12, 13, 14, 15, 16, 17,18,19, 20, 21, and 22, allconnected together and placed two at each end and two in the center of each side of the car; the finger A being connected with heater 11; B, with heaters 21 and 22; C with heaters 16 and 17; D with heater 12; E with heaters 19 and 20.
- the currentpasscs first to heater 12, then to heaters 15, 18, 21, 22, 20, 19, 17, 16, 14-, 13 and 11 and through the ground wire at- A out, having twelve heaters in the series.
- the second series is in connection, the current passes from finger B to heaters 22, 20, 19, 17, 1(3, 14, 13 and 11, having eight heaters in series.
- the third series is in connection, the current passes from finger E to heaters 19, 17, 16, 14, 13 and 11 and heaters 20, 22, 21, 18, 15 and 12, making two series of six heaters each.
- fourth series is in connection, the current passes from the finger O to heaters 16, 14, 13 and 11 and heaters 17, 19, 20 and 22, making two series of four heaters each.
- the fifth series is in connection, the current passes from finger D to heaters 12, 15, 18 and 21 and from finger O to heaters 16, 1 1, 13 and 11 and 17, 19, 20 and 22, making three series of four When the heaters each.
- the total heating surface is divided into two equal parts, and these parts are placed in multiple with reference to each other.
- the fourth position two-thirds of the heating surface is divided into two equal parts and these parts are placed in multiple with reference to each other.
- the fifth position the total heating surface is divided into three equal parts and these parts are placed in multiple with reference to each other.
- I In heating up a car, I preferably place the switch in the fifth position, allowing a large current to flow through the heater, hence I obtain a rapid heating of the car. As the car becomes warm ready to go on the road,I then turn the switch in one of the other positions requiring less current; the position of the switch depending upon the temperature of the outside air. As the flow of current commences, the heating effect may be varied in this manner. Thus I am enabled to set the switch so as to give just the heat required to make a car comfortable in any weather.
- a cylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, the periphery of the cylinder cut away immediately above each of said plugs, leaving each of said metallic plugs flush with the surface, substantially as described and for the purpose set forth.
- a cylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, the periphery of the cylinder cut away immediately above each of said plugs, leaving each of said metallic plugs flush with the surface, a metallic rod connecting two or more of said metallic plugs, substantially as described and for thepurpose set forth.
- a cylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, with the periphery of the cylinder cut away immediately above each of said plugs leaving each of said plugs flush with the surface, a spindle upon which said cylinder is mounted, a series of electric fingers in contact with said metallic plugs,each of said fingers attached toa wire carrying the current of electricity to the switch, one of said fingers attached to a wire connected with the ground, substantially as described and for the purpose set forth.
- a cylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, with the periphery of the cylinder cut away immediately above each of said plugs leaving each of said plugs flush with the surface, a series of metallic fingers arranged to come in contact with said metallic plugs in the course of a revolution of the cylinder in such a manner that all the metallic plugs in each series will be in contact with their corresponding fingers simultaneously, substantially as described and for the purpose set forth.
- acylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, with the periphery of the cylinder cut away immediately above each of said plugs leaving each of said plugs flush with the surface, a series of metallic I fingers arranged to come in contact with said metallic plugs in the course of a revolution of the cylinder in such a manner that all the metallic plugs in each series will be in contact with their corresponding fingers simul taneously, a spindle upon which said cylinder is mounted, said spindle journaled in a suitable frame, with a knob at the end of said spindle by means of which the cylinder may be rotated, substantially as described and for the purpose set forth.
- acylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, with the periphery of the cylinder cut away immediately above each of said plugs leaving each of said plugs flush with the surface, a series of metallic fingers arranged to come in contact with said metallic plugs in the course of a revolution of the cylinder in such a manner that all the metallic plugs in each series will be in contact with their corresponding fingers s multaneously, a spindle upon which said cylinder is mounted, said spindle journaled in a su table frame, with a knob at the end of sa1d spindle by means of which the cylinder may be rotated, a rocking shaft mounted in sa1d frame, a bell crank lever secured to sa1d rocking shaft, a metallic disk on one arm of sa1d bell crank lever adapted to make and break the circuit
- a cylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its ax s, a series of metallic plugs placed within sa1d passage ways, insulating material placed between said metallic plugs, with the periphery of the cylinder cut away immediately above each of said plugs leaving each of said plugs fingers arranged to come in contact with said metallic plugs in the course of a revolution of the cylinder in such a manner that all the metallic plugs in each series will be in contact with their corresponding fingers simultaneously, a spindle upon which said cylinder is mounted, said spindle journaled in a suitable frame, with a knob at the end of said spindle by means of which the cylinder may be rotated, one end of said cylinder provided with a wheel,anotched or corrugated periphshaft suitably journaled to the frame of the switch, one arm of said shaft provided with a lug fitted to engage in the notches in said wheel by means of which said cylinder may be
Landscapes
- Control Of Resistance Heating (AREA)
Description
(No Model.) 3 Sheets-Sheet 1.
' J. F.1VI0ELR0Y.
ELEGTR'IG SWITGH.
Patented May 8, 1894.
44-5. W- Aljfmm 5351i (m Model.) s Sheets-Sheet 2-, i
" v J. F. MoELROY. ELECTRIC SWITCH.
Patented May 8, v1894.
UNITED STATES DATED CAR-HEATING COMPANY,
PATENT JAMES F. MOELROY, OF ALBANY, NEW YORK, ASSIG-NOR TO THE CONSOLI- OF WHEELING, WEST VIRGINIA.
ELECTRIC SWITCH.
SPECIFICATION forming part of Letters Patent No. 519,338, dated May 8, 1894.
Application filed August 2, 1 8 9 3.
To all whom it may concern.-
Be it known that 1, JAMES F. MOELROY, a citizen of the United States, residing in the city and county of Albany, State of New York, have invented a new and useful Electrio Switch, of which the following is a specification.
My invention relates to improvements in mechanism for directing the current of electricity; and the object of my invention is to provide an electric switch particularly adapted for use in mechanism for heating with electricity. I accomplish this object by means of the mechanism illustrated in the accompanying drawings, in which- Figure 1 is a plan. Fig. 2 is an end elevation. Fig. 3 is a side elevation. Fig. 4 is a longitudinal section. Fig. 5 is a detail View showing the connections between the metallic plugs in the cylinder. Fig. 6 is an end elevation of the knob H. Fig. 7 is a seriesof cross sections of the cylinder showing the position of the metallic plugs therein, and Fig. 8 is a View of the wiring in the car.
Similar letters and figures refer to similar parts throughout the several views.
The cylinder X is composed of any suitable material and mounted upon a spindle d journaled Within the box G and has keyed to it at one end the knob H. At one end of the cylinder and secured thereto, I arrange the notched wheel W'. Before mounting the cylinder, I core out a series of passage ways extending in a path parallel to its axis; said passage ways usually extending from one end of the cylinder to the other. Within the passage Ways thus cored out of the cylinder, I place a series of metallic plugs 10 separated by an insulating substance Z; said plugs sometimes connected by metallic rods R in the manner hereinafter described. After placing the plugs 10 and the insulating substance Z in position, I put the cylinder upon a lathe and cut down the surface of the cylinder immediately above the plugs placed within the cylinder forming a series of annulardepressions, A, B, C, D, E and F extending around the cylinder, until the metallic plugs are flush with the periphery, making thus a series of narrow partitions on between the annular depressions A, B, O, D,E and F.
Serial No. 482,180- (No model.)
I arrange the metallic plugs 19 as shown in Figs. 1, 3, and 4. Thus in section A there are three plugs, (see Fig. 7) section B also contains three plugs; section C two, section D three; section E one and section F five. By referring to Fig. 5 the letters at the bottom of the figure refer to the sections and show by the number of squares in the upright column in full lines, the number of metallic plugs in each section. The figures at the right of Fig. 5 refer to the various series of metallic plugs in the section and show how they are connected.
I have indicated on Figs. 1, 3, 4 and 7 the positions of the various plugs and numbered them according to which series they belong. Thus in Fig. 1 at the top of the cylinder, is seen series 1; lower down is series 2, while the springs are in contact with series 8. Fig. 4 shows the connection of the plugs of the third series, in which the plug in section Ais connected with the plug in section D by means of the rod R separated by the insulating material Z. The plug in section E extends through into section F.
Within the box G, I mount the rocking shaft J carrying a spiral springj and having pivoted to it the bell-crank lever'K. I One end of the lever K is provided with a handle it; the opposite end carries the metallic disk K. One side of the arm of the lever which carries the disk K is provided with a stud Z constructed to engage with the openings L in the wheel Wwhen the disk K is between the posts M and N. The disk K is constructed to fit snugly between the metallic posts M and N; the posts M and N are insulated from the box and cylinder, as is also the disk K from the lever K. The post N is connected by wire to one pole of the battery; the postM is connected by wire to an electric finger F; said electric finger F being attached to an insulated bolt in the frame of the box at one end, itsother end being in contact with section F of the cylinder. In a similar way the fingers E, D, C, B, and A are arranged in contact with the corresponding sections of the cylinder. Thus in Fig. 4 the current passes from the battery to the postNthrough disk K to the post M and is carried to finger F (see Fig. 1) thence to the plug in sections E and F, thence through linger E to the resistance to be heated and returns to the finger E and plug in section D and is conducted to the plug in section A from thence it passes to the ground.
By the operation of the bell-crank lever K, the circuit is made or broken. hen the circuit is complete, the disk K being in position between the posts M and N, the cylinder is locked, the lug I within the wheel 1V prevents the oscillation of the cylinder, and in order to change the position of the cylinder and thereby operate the switch, it is necessary to first break the circuit by operating the lever. The numbers on the knob II shown in Fig. 6, indicate the position of the cylinder and after the lever is drawn back, the cylinder may be revolved by means of the knob to the position indicated by the figures and then the circuit may be made and the switch placed in operation. By this construction of the switch and locking device, I prevent sparking at the spring contact with the cylinder, which would take place if the circuit were made when the cylinder was revolved, and I make and break the circuit at a point above the cylinder, which is controlled by the lever. It will be noticed that the lever performs a double function, first that of breaking the circuit, and second that of locking the I'Ollttl cylinder in position, so that it cannot be turned until after the circuit is broken. It moreover makes it impossible to close the circuit through the switch when the cylinder is not in its proper position.
I describe one adaptation of my switch, that connected with heating by electricity. The heaters in the car are numbered 11, 12, 13, 14, 15, 16, 17,18,19, 20, 21, and 22, allconnected together and placed two at each end and two in the center of each side of the car; the finger A being connected with heater 11; B, with heaters 21 and 22; C with heaters 16 and 17; D with heater 12; E with heaters 19 and 20. By this arrangement of the heaters and their connections when the fingers D and F are in contact with the plugs in disks D and F, as shown on series 1, the currentpasscs first to heater 12, then to heaters 15, 18, 21, 22, 20, 19, 17, 16, 14-, 13 and 11 and through the ground wire at- A out, having twelve heaters in the series. \Vhen the second series is in connection, the current passes from finger B to heaters 22, 20, 19, 17, 1(3, 14, 13 and 11, having eight heaters in series. lVhen the third series is in connection, the current passes from finger E to heaters 19, 17, 16, 14, 13 and 11 and heaters 20, 22, 21, 18, 15 and 12, making two series of six heaters each. fourth series is in connection, the current passes from the finger O to heaters 16, 14, 13 and 11 and heaters 17, 19, 20 and 22, making two series of four heaters each. hen the fifth series is in connection, the current passes from finger D to heaters 12, 15, 18 and 21 and from finger O to heaters 16, 1 1, 13 and 11 and 17, 19, 20 and 22, making three series of four When the heaters each. In the first; position all of the heating surface within the car is placed in series. In the second position two-thirds are placed in series. In the third position, the total heating surface is divided into two equal parts, and these parts are placed in multiple with reference to each other. In the fourth position, two-thirds of the heating surface is divided into two equal parts and these parts are placed in multiple with reference to each other. In the fifth position, the total heating surface is divided into three equal parts and these parts are placed in multiple with reference to each other.
In heating up a car, I preferably place the switch in the fifth position, allowing a large current to flow through the heater, hence I obtain a rapid heating of the car. As the car becomes warm ready to go on the road,I then turn the switch in one of the other positions requiring less current; the position of the switch depending upon the temperature of the outside air. As the flow of current commences, the heating effect may be varied in this manner. Thus I am enabled to set the switch so as to give just the heat required to make a car comfortable in any weather.
WVhat I claim as my invention, and desire to secure by Letters Patent, is
1. In an electric switch, a cylinderprovided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, the periphery of the cylinder cut away immediately above each of said plugs, leaving each of said metallic plugs flush with the surface, substantially as described and for the purpose set forth.
2. In an electric switch, a cylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, the periphery of the cylinder cut away immediately above each of said plugs, leaving each of said metallic plugs flush with the surface, a metallic rod connecting two or more of said metallic plugs, substantially as described and for thepurpose set forth.
3. In an electric switch, a cylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, with the periphery of the cylinder cut away immediately above each of said plugs leaving each of said plugs flush with the surface, a spindle upon which said cylinder is mounted, a series of electric fingers in contact with said metallic plugs,each of said fingers attached toa wire carrying the current of electricity to the switch, one of said fingers attached to a wire connected with the ground, substantially as described and for the purpose set forth.
IIO
4. In an electric switch, a cylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, with the periphery of the cylinder cut away immediately above each of said plugs leaving each of said plugs flush with the surface, a series of metallic fingers arranged to come in contact with said metallic plugs in the course of a revolution of the cylinder in such a manner that all the metallic plugs in each series will be in contact with their corresponding fingers simultaneously, substantially as described and for the purpose set forth.
5. In an electric switch, acylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, with the periphery of the cylinder cut away immediately above each of said plugs leaving each of said plugs flush with the surface, a series of metallic I fingers arranged to come in contact with said metallic plugs in the course of a revolution of the cylinder in such a manner that all the metallic plugs in each series will be in contact with their corresponding fingers simul taneously, a spindle upon which said cylinder is mounted, said spindle journaled in a suitable frame, with a knob at the end of said spindle by means of which the cylinder may be rotated, substantially as described and for the purpose set forth.
6. In an electric switch,acylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its axis, a series of metallic plugs placed within said passage ways, insulating material placed between said metallic plugs, with the periphery of the cylinder cut away immediately above each of said plugs leaving each of said plugs flush with the surface, a series of metallic fingers arranged to come in contact with said metallic plugs in the course of a revolution of the cylinder in such a manner that all the metallic plugs in each series will be in contact with their corresponding fingers s multaneously, a spindle upon which said cylinder is mounted, said spindle journaled in a su table frame, with a knob at the end of sa1d spindle by means of which the cylinder may be rotated, a rocking shaft mounted in sa1d frame, a bell crank lever secured to sa1d rocking shaft, a metallic disk on one arm of sa1d bell crank lever adapted to make and break the circuit by entering or leaving the space between the two poles of the switch, substantially as described and for the purpose set forth.
7. In an electric switch, a cylinder provided with a series of passage ways cored therefrom and extending in a path parallel to its ax s, a series of metallic plugs placed within sa1d passage ways, insulating material placed between said metallic plugs, with the periphery of the cylinder cut away immediately above each of said plugs leaving each of said plugs fingers arranged to come in contact with said metallic plugs in the course of a revolution of the cylinder in such a manner that all the metallic plugs in each series will be in contact with their corresponding fingers simultaneously, a spindle upon which said cylinder is mounted, said spindle journaled in a suitable frame, with a knob at the end of said spindle by means of which the cylinder may be rotated, one end of said cylinder provided with a wheel,anotched or corrugated periphshaft suitably journaled to the frame of the switch, one arm of said shaft provided with a lug fitted to engage in the notches in said wheel by means of which said cylinder may be locked, with a disk at the end of said lever arm adapted to fit between the poles of the switch, substantially as described and for the purpose set forth.
JAIVIES F. MCELROY.
Witnesses:
RALPH W. KIRKHAM, MARY AGNES BURKE.
cry on said wheel, a lever mounted upon a flush with the surface, a series of metallic
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US519338A true US519338A (en) | 1894-05-08 |
Family
ID=2588136
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US519338D Expired - Lifetime US519338A (en) | moelroy |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US519338A (en) |
-
0
- US US519338D patent/US519338A/en not_active Expired - Lifetime
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3340382A (en) | Multi-cell electrical heater | |
| US519338A (en) | moelroy | |
| US1118024A (en) | Electrical switch. | |
| US499363A (en) | Electric switch | |
| US1494516A (en) | Steering wheel | |
| US1395584A (en) | Multiple-unit electric heater | |
| US755468A (en) | Rheostat. | |
| US3178850A (en) | Electrical smoke generator | |
| US1213811A (en) | Steering-wheel post. | |
| US1110415A (en) | Apparatus for producing ignition-sparks within cylinders of internal-combustion engines. | |
| US1286705A (en) | Permutation electric switch. | |
| US690800A (en) | Battery-end-cell switch-indicator. | |
| US322310A (en) | euset | |
| US1478342A (en) | Electrical air condenser | |
| US1177976A (en) | Dimmer for automobile-headlights. | |
| US489212A (en) | Temperature-indicator | |
| US569300A (en) | powell | |
| US1084220A (en) | Apparatus for the electric lighting of motor-cars and for other purposes. | |
| US746128A (en) | Electric heating element. | |
| US712749A (en) | Rheostat. | |
| US749628A (en) | Electric heater | |
| US372012A (en) | Electrical resistance-board | |
| US516152A (en) | Electrical heater | |
| US687569A (en) | Rheostat. | |
| US1471432A (en) | Device for testing electric circuits |