US58105A - Improvement in magneto-electric apparatus - Google Patents

Improvement in magneto-electric apparatus Download PDF

Info

Publication number
US58105A
US58105A US58105DA US58105A US 58105 A US58105 A US 58105A US 58105D A US58105D A US 58105DA US 58105 A US58105 A US 58105A
Authority
US
United States
Prior art keywords
helix
helices
current
currents
wire
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
Application number
Publication date
Application granted granted Critical
Publication of US58105A publication Critical patent/US58105A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00Details of transformers or inductances, in general
    • H01F27/40Structural association with built-in electric component, e.g. fuse

Definitions

  • My invention consists in arranging two helices or systems of helices in connection with a galvanic battery, so that the battery-current is thrown successively through the primary coil of one helix or system of helices and that of the other helix or system of helices-thatis to say, is first thrown through one helix or system, then interrupted and thrown through the other, so as to create induced currents in one helix or system of helices, then imme diately in succession creating induced currents in the other helix or system of helices.
  • My invention consists, further, in ar "anging the helices with relation to the battery-current and the induction-coils, so that the terminal currents produced by the interruption of the primary circuit may be received from the two systems of helices alternately in opposite directions, thus producing equal alternating currents.
  • lt also consists in changing the direction of the primary current in one of the coils, or its equivalent, by reversing the position of the ends of one of the coils receiving the induced currents, making the terminal currents all pass in one uniform direction.
  • Myinvention consists,furthcr,in an arrangement to secure the screws pressing against the vibrating spring, or its equivalent, so that they will remain stationary and firm to whatever place adjusted without the use of a binding nut on the screw itself, so as to be adjusted by my arrangement more easily and perfectly than by the ordinary method of using binding nuts upon these screws, which latter would not admit of perfect adjustment with facility, because when the screw is advanced to the exact distance required the friction of the ordinary nut to secure it turns the screw alittle farther, and makes the perfect adj ustmentrequired adiflicult matter.
  • My invention consists, further, in arranging the systems of helices for inductioil-currents so that they can be exchanged for other helices.
  • My invention consists, further, in arranging the helices for the induced currents so that a current of high quantity andof low tension may be alternatelysucceeded by a current of low quantity and of high tension, passing either in the same or in the opposite direction.
  • L is a stand, of wood, on which is mounted the block N, in which is fastened one end of each of the two helices S S, of coarse wire.
  • Each of these helices passes through a spool of fine insulated wire, T T, and the first ends of the wire of the spools are att t and the last ends at a a, Fig. 1.
  • the last end a of the wire of the spool T on the helix S is connected by a wire with the first end of the wire tof the spool T on the helix S.
  • the ends of the helices S S most distant from the block have also support, besides suspension, by means of upright hinged metallic strips, kept in place by spring'catches r r.
  • a and E are metallic posts, having sockets and binding screws to connect with the battery.
  • B B are bases of the upright or inclined metallic supports-for the screws 8 s, which, at their points, press against the springs b Zr, which are at their bottom ends securely fastened to the lower parts of B B.
  • O is an armature, having at each end iron 2 seams hammers H H, opposing the iron screws f f, which are inserted into iron cores of the helices S S.
  • This armature G is supported by an upright spring, I, of thin steel-plate, the lower end of which is fastened to a plate, P, secured below the stand L, and the upper end fastened to an arm, D on the top of a fixed post, D, by means of a screw on the upper end of the spring and a nut resting on the said arm. By screwing up the said nut the requisite tension may be given to the spring.
  • the screws Z Z fasten the supports B B to the stand L.
  • the upright supports B B are divided at the top, (shown at. 3 y,) where the screws 8 8 pass, and the separated portions are bound against the screws 8 s by means of other screws, 1) v.
  • the disks a 0 p q are for contact at one end with the switches to x, which have sup ports, on which they turn, at W X.
  • a is the first end of the coarse wire of the helix S, and (0 its last end. The first end is joined with the post A, and also continues at w and is joined to the pivot WV of the switch 'w.
  • h is the first end of the coarse wire of the helix S, joined to the disks 1) and 0, and h is the last end of the said wire, connected with the disks n and q.
  • the pivot X of the switch a is connected with the upright B by means of the wire g.
  • the positive current of the battery follows through a into the helix S, whence it follows the wire a to B, and through the spring I), and thence through the platinum disk on the end of this spring, to the platinum rivet c on the armature 0, when the latter is set in motion, so as to make contact; thence through the spring to the column D; thence by the wire (I to the post E, and to the negative pole of the battery.
  • the iron core of the helix S is made a magnet by the primary circuit, and, its extremity being the iron screw f, attracts the hammer H, drawing away the armature, so as to break the connection between the spring I) "and the armature C.
  • the battery-current passes through the helix S in an opposite direction from that of its passage through the helix S, and consequently the induced current developed upon the helix T is in an opposite direction from that developed in the helix T, the positive'pole of the current developed on T being at t, and the negative at u or when t has metallic connection with a, the current passes through the helix T, as a conducting medium, and then the positive is at t.
  • the strong terminal induce currents resulting from the interruption of the battery-circuit are in opposite directions, and they are received alternately from the poles u and it.
  • the ivory bar 11 by means of its knobs k so that the switch to is placed on the disk 1) and the switch as on the disk at, then, as will readily be observed, the battery-current passes through the helix S in the same direction that it passes through the helix S; consequently the induced currents developed on the helix T will in this case be in the same direction as those developed on the helix T, and they will flow successively in "one uniform direction.

Description

J. KIDDER.
Electro-Magnetic Apparatus.
Patented Sept. 18, 1866.
N. PETERS. Hmmurm m mr. Washlllglun. n. c.
UNITED STATES PATENT JEROME KIDDER, OF NEW YORK, N. Y.
IMPROVEMENT IN MAGNETO-ELECTRIC APPARATUS.
Specification forming part of Letters Patent No. 58,105, dated September 18, 1866.
To all whom it may concern:
Be it known that I, JEROME KIDDER, of the city, county, and State of New York, have invented certain new an d useful Improvements in Electro Magnetic Apparatus; and I do hereby declare that the followingis a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l is a plan view of an apparatusillustrating my invention. Fig. 2 is an end view of the same.
Similar letters of reference indicate correspondin g parts in the several figures.
My invention consists in arranging two helices or systems of helices in connection with a galvanic battery, so that the battery-current is thrown successively through the primary coil of one helix or system of helices and that of the other helix or system of helices-thatis to say, is first thrown through one helix or system, then interrupted and thrown through the other, so as to create induced currents in one helix or system of helices, then imme diately in succession creating induced currents in the other helix or system of helices.
It consists, further, in so arranging the two helices or systems of helices receiving the induced currents in combination that the current or currents developed in either one may be thrown through the other as a conducting medium, and hence that, by taking the extremities of the connected coils for a closed circuit, as through the body, the current or currents developed on one helix or system of helices will be received, and then the current or currents developed on the other helix or system of helices will be received, so the difi'erent currents will pass through the body from one and the other in continued succession. J
My invention consists, further, in ar "anging the helices with relation to the battery-current and the induction-coils, so that the terminal currents produced by the interruption of the primary circuit may be received from the two systems of helices alternately in opposite directions, thus producing equal alternating currents.
lt also consists in changing the direction of the primary current in one of the coils, or its equivalent, by reversing the position of the ends of one of the coils receiving the induced currents, making the terminal currents all pass in one uniform direction.
Myinvention consists,furthcr,in an arrangement to secure the screws pressing against the vibrating spring, or its equivalent, so that they will remain stationary and firm to whatever place adjusted without the use of a binding nut on the screw itself, so as to be adjusted by my arrangement more easily and perfectly than by the ordinary method of using binding nuts upon these screws, which latter would not admit of perfect adjustment with facility, because when the screw is advanced to the exact distance required the friction of the ordinary nut to secure it turns the screw alittle farther, and makes the perfect adj ustmentrequired adiflicult matter.
My invention consists, further, in arranging the systems of helices for inductioil-currents so that they can be exchanged for other helices.
My invention consists, further, in arranging the helices for the induced currents so that a current of high quantity andof low tension may be alternatelysucceeded by a current of low quantity and of high tension, passing either in the same or in the opposite direction.
To enable those skilled in the art to make and use my invention, I will proceed to describe it with reference to the drawings.
, L is a stand, of wood, on which is mounted the block N, in which is fastened one end of each of the two helices S S, of coarse wire. Each of these helices passes through a spool of fine insulated wire, T T, and the first ends of the wire of the spools are att t and the last ends at a a, Fig. 1. The last end a of the wire of the spool T on the helix S is connected by a wire with the first end of the wire tof the spool T on the helix S. The ends of the helices S S most distant from the block have also support, besides suspension, by means of upright hinged metallic strips, kept in place by spring'catches r r.
A and E are metallic posts, having sockets and binding screws to connect with the battery.
B B are bases of the upright or inclined metallic supports-for the screws 8 s, which, at their points, press against the springs b Zr, which are at their bottom ends securely fastened to the lower parts of B B.
O is an armature, having at each end iron 2 seams hammers H H, opposing the iron screws f f, which are inserted into iron cores of the helices S S. This armature G is supported by an upright spring, I, of thin steel-plate, the lower end of which is fastened to a plate, P, secured below the stand L, and the upper end fastened to an arm, D on the top of a fixed post, D, by means of a screw on the upper end of the spring and a nut resting on the said arm. By screwing up the said nut the requisite tension may be given to the spring. I
The screws Z Z fasten the supports B B to the stand L. The upright supports B B are divided at the top, (shown at. 3 y,) where the screws 8 8 pass, and the separated portions are bound against the screws 8 s by means of other screws, 1) v.
The disks a 0 p q are for contact at one end with the switches to x, which have sup ports, on which they turn, at W X.
As the helix is wound, a is the first end of the coarse wire of the helix S, and (0 its last end. The first end is joined with the post A, and also continues at w and is joined to the pivot WV of the switch 'w.
h is the first end of the coarse wire of the helix S, joined to the disks 1) and 0, and h is the last end of the said wire, connected with the disks n and q.
The pivot X of the switch a: is connected with the upright B by means of the wire g.
A piece of ivory or non-conducting material,
i ,-connects the ends of the switches w and m. K is a knob upon this piece of ivory. There are rivets of platinum c and c, which, when the bar 0 vibrates, connect with the platinum gilsks opposite them on the ends of the springs 1 will now proceed to show the operation of the machine. The post A is connected with the positive pole of the battery, and the post E with the negative pole. It will be seen that the positive current of the battery follows through a into the helix S, whence it follows the wire a to B, and through the spring I), and thence through the platinum disk on the end of this spring, to the platinum rivet c on the armature 0, when the latter is set in motion, so as to make contact; thence through the spring to the column D; thence by the wire (I to the post E, and to the negative pole of the battery. The iron core of the helix S is made a magnet by the primary circuit, and, its extremity being the iron screw f, attracts the hammer H, drawing away the armature, so as to break the connection between the spring I) "and the armature C. At the time of this interruption there is a powerful induced current developed on the coil T, and the positive of this induced current is at a, and a is connected with t on the helix T. The positive of this induced current"developed on T is conducted through the helix T, and then the positive of the current developed on T is extended to a, while the negative is at it. Now, when the primary current is interrupted from the helix S by the swing of the armature O, the
helix S is closed in the battery-circuit through the point e in this wise: The positive of the primary current follows from A over a to the pivot W, and over the switch w to the disk q and the wire h, which is the last end of the helix S, traversing the said helix, and finally flowing out on the wire h to the disk 0,- then along the switch .a: and wire 9 to the base of the metallic u n-ight B"; thence through the spring I) to the platinum rivet c of the armature O; thence through the spring I to the column D, and thence along the wire (I to the screw-cup E, connected with the negative of the battery. It will be seen that in this case the battery-current passes through the helix S in an opposite direction from that of its passage through the helix S, and consequently the induced current developed upon the helix T is in an opposite direction from that developed in the helix T, the positive'pole of the current developed on T being at t, and the negative at u or when t has metallic connection with a, the current passes through the helix T, as a conducting medium, and then the positive is at t.
It will be readily seen that when the apparatus is thus operating, and we use as poles the extreme terminals to and tof the fine wire of the two helices T and T thus united, we
have an equal alternating current-that is,
the strong terminal induce currents resulting from the interruption of the battery-circuit are in opposite directions, and they are received alternately from the poles u and it. But if we move the ivory bar 11 by means of its knobs k so that the switch to is placed on the disk 1) and the switch as on the disk at, then, as will readily be observed, the battery-current passes through the helix S in the same direction that it passes through the helix S; consequently the induced currents developed on the helix T will in this case be in the same direction as those developed on the helix T, and they will flow successively in "one uniform direction. Also, it will be seen that by this arrangement different qualities of currents, by modifying the power or the quantity or tension, may be made to pass in succession, and either in one uniform direction or in opposite directions. It will be seen that, taking the poles at t and a, the current developed on each helix meets with a certain amount of resistance, because of the interposed coil which it has in each case (developed from each helix) to pass through offering a certain amount of resistance. Also, if the points t and u be united at Y, Fig. 1, and the point Z be taken as one pole, (which is both a and t,) and Y be taken as the other pole, then the currents on T and T can also be alternately received through the body; and in this case, though the coil of each helix is immediately closed through the body, it is also closed through the medium of the opposite coil, which likewise receives a certain portion of the developed current, and that proportion received by this opposite coil (as T when using T, or T when using T) is smaller as the length of the resistin g coil is increased.
By means of the screws u v the sections y y of the supports B B are bound against the screws 8 s, so as to hold them firmly, admitting of no looseness, (as looseness would not admit of operation,) and yet admitting of easy turning for their advancement or withdrawal, thus facilitating the necessarily delicate, to an easy and perfect, adjustment of the proper amount of pressure of the point of the screws against the springs 11 1) against the platinum points 0 c.
What I claim as my invention, and desire to secure by Letters Patent, is-
1. The construction and arrangement of an electromagnetic apparatus, whereby the primary current through two helices or systems of helices is thrown successively in opposite directions, or so as to develop induced currents successively in opposite directions, substantially as herein described.
2. The arrangement of the parts of an electro-magnetic apparatus, whereby the currents from two helices or systems of helices are made to flow in succession, one immediately after the other, in a uniform direction, substantially as herein set forth, such currents being either of the same character, made thus more rapid in succession, or of different degrees of tension or concentrative or difl'nsive influence.
3. For adjusting the screw opposed to the vibrating spring of an electromagnetic apparatus, the use of the arrangement as represented by u y, operating substantially in the manner described.
JEROME KIDDER.
Witnesses:
HENRY. T. BROWN, J. W. 000M138.
US58105D Improvement in magneto-electric apparatus Expired - Lifetime US58105A (en)

Publications (1)

Publication Number Publication Date
US58105A true US58105A (en) 1866-09-18

Family

ID=2127644

Family Applications (1)

Application Number Title Priority Date Filing Date
US58105D Expired - Lifetime US58105A (en) Improvement in magneto-electric apparatus

Country Status (1)

Country Link
US (1) US58105A (en)

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090159919A1 (en) * 2007-12-20 2009-06-25 Altair Engineering, Inc. Led lighting apparatus with swivel connection
US20090290334A1 (en) * 2008-05-23 2009-11-26 Altair Engineering, Inc. Electric shock resistant l.e.d. based light
US20100008085A1 (en) * 2008-07-09 2010-01-14 Altair Engineering, Inc. Method of forming led-based light and resulting led-based light
US20100027259A1 (en) * 2008-07-31 2010-02-04 Altair Engineering, Inc. Fluorescent tube replacement having longitudinally oriented leds
US20100052542A1 (en) * 2008-09-02 2010-03-04 Altair Engineering, Inc. Led lamp failure alerting system
US20100067231A1 (en) * 2008-09-15 2010-03-18 Altair Engineering, Inc. Led-based light having rapidly oscillating leds
US20100103664A1 (en) * 2008-10-24 2010-04-29 Altair Engineering, Inc. Lighting including integral communication apparatus
US20100106306A1 (en) * 2008-10-24 2010-04-29 Altair Engineering, Inc. Integration of led lighting with building controls
US20100102730A1 (en) * 2008-10-24 2010-04-29 Altair Engineering, Inc. Light and light sensor
US20100103673A1 (en) * 2008-10-24 2010-04-29 Altair Engineering, Inc. End cap substitute for led-based tube replacement light
US20100102960A1 (en) * 2008-10-24 2010-04-29 Altair Engineering, Inc. Integration of led lighting control with emergency notification systems
US20100172149A1 (en) * 2007-12-21 2010-07-08 Altair Engineering, Inc. Light distribution using a light emitting diode assembly
US20100177532A1 (en) * 2009-01-15 2010-07-15 Altair Engineering, Inc. Led lens
US20100181933A1 (en) * 2009-01-21 2010-07-22 Altair Engineering, Inc. Direct ac-to-dc converter for passive component minimization and universal operation of led arrays
US20100181925A1 (en) * 2009-01-21 2010-07-22 Altair Engineering, Inc. Ballast/Line Detection Circuit for Fluorescent Replacement Lamps
US20100220469A1 (en) * 2008-05-23 2010-09-02 Altair Engineering, Inc. D-shaped cross section l.e.d. based light
US20100321921A1 (en) * 2009-06-23 2010-12-23 Altair Engineering, Inc. Led lamp with a wavelength converting layer
US20100320922A1 (en) * 2009-06-23 2010-12-23 Altair Engineering, Inc. Illumination device including leds and a switching power control system
US20110235318A1 (en) * 2010-03-26 2011-09-29 Altair Engineering, Inc. Led light tube with dual sided light distribution
US8454193B2 (en) 2010-07-08 2013-06-04 Ilumisys, Inc. Independent modules for LED fluorescent light tube replacement
US8541958B2 (en) 2010-03-26 2013-09-24 Ilumisys, Inc. LED light with thermoelectric generator
US8870415B2 (en) 2010-12-09 2014-10-28 Ilumisys, Inc. LED fluorescent tube replacement light with reduced shock hazard
US10560992B2 (en) 2008-10-24 2020-02-11 Ilumisys, Inc. Light and light sensor

Cited By (40)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8118447B2 (en) 2007-12-20 2012-02-21 Altair Engineering, Inc. LED lighting apparatus with swivel connection
US20090159919A1 (en) * 2007-12-20 2009-06-25 Altair Engineering, Inc. Led lighting apparatus with swivel connection
US7926975B2 (en) 2007-12-21 2011-04-19 Altair Engineering, Inc. Light distribution using a light emitting diode assembly
US20100172149A1 (en) * 2007-12-21 2010-07-08 Altair Engineering, Inc. Light distribution using a light emitting diode assembly
US20090290334A1 (en) * 2008-05-23 2009-11-26 Altair Engineering, Inc. Electric shock resistant l.e.d. based light
US20100220469A1 (en) * 2008-05-23 2010-09-02 Altair Engineering, Inc. D-shaped cross section l.e.d. based light
US8360599B2 (en) 2008-05-23 2013-01-29 Ilumisys, Inc. Electric shock resistant L.E.D. based light
US20100008085A1 (en) * 2008-07-09 2010-01-14 Altair Engineering, Inc. Method of forming led-based light and resulting led-based light
US7976196B2 (en) 2008-07-09 2011-07-12 Altair Engineering, Inc. Method of forming LED-based light and resulting LED-based light
US20100027259A1 (en) * 2008-07-31 2010-02-04 Altair Engineering, Inc. Fluorescent tube replacement having longitudinally oriented leds
US7946729B2 (en) 2008-07-31 2011-05-24 Altair Engineering, Inc. Fluorescent tube replacement having longitudinally oriented LEDs
US8674626B2 (en) 2008-09-02 2014-03-18 Ilumisys, Inc. LED lamp failure alerting system
US20100052542A1 (en) * 2008-09-02 2010-03-04 Altair Engineering, Inc. Led lamp failure alerting system
US8256924B2 (en) 2008-09-15 2012-09-04 Ilumisys, Inc. LED-based light having rapidly oscillating LEDs
US20100067231A1 (en) * 2008-09-15 2010-03-18 Altair Engineering, Inc. Led-based light having rapidly oscillating leds
US20100102960A1 (en) * 2008-10-24 2010-04-29 Altair Engineering, Inc. Integration of led lighting control with emergency notification systems
US8324817B2 (en) 2008-10-24 2012-12-04 Ilumisys, Inc. Light and light sensor
US11333308B2 (en) 2008-10-24 2022-05-17 Ilumisys, Inc. Light and light sensor
US10932339B2 (en) 2008-10-24 2021-02-23 Ilumisys, Inc. Light and light sensor
US7938562B2 (en) 2008-10-24 2011-05-10 Altair Engineering, Inc. Lighting including integral communication apparatus
US10560992B2 (en) 2008-10-24 2020-02-11 Ilumisys, Inc. Light and light sensor
US20100103664A1 (en) * 2008-10-24 2010-04-29 Altair Engineering, Inc. Lighting including integral communication apparatus
US20110188240A1 (en) * 2008-10-24 2011-08-04 Altair Engineering, Inc. Lighting including integral communication apparatus
US20100106306A1 (en) * 2008-10-24 2010-04-29 Altair Engineering, Inc. Integration of led lighting with building controls
US20100103673A1 (en) * 2008-10-24 2010-04-29 Altair Engineering, Inc. End cap substitute for led-based tube replacement light
US8214084B2 (en) 2008-10-24 2012-07-03 Ilumisys, Inc. Integration of LED lighting with building controls
US8251544B2 (en) 2008-10-24 2012-08-28 Ilumisys, Inc. Lighting including integral communication apparatus
US20100102730A1 (en) * 2008-10-24 2010-04-29 Altair Engineering, Inc. Light and light sensor
US8556452B2 (en) 2009-01-15 2013-10-15 Ilumisys, Inc. LED lens
US20100177532A1 (en) * 2009-01-15 2010-07-15 Altair Engineering, Inc. Led lens
US8664880B2 (en) 2009-01-21 2014-03-04 Ilumisys, Inc. Ballast/line detection circuit for fluorescent replacement lamps
US20100181933A1 (en) * 2009-01-21 2010-07-22 Altair Engineering, Inc. Direct ac-to-dc converter for passive component minimization and universal operation of led arrays
US20100181925A1 (en) * 2009-01-21 2010-07-22 Altair Engineering, Inc. Ballast/Line Detection Circuit for Fluorescent Replacement Lamps
US20100321921A1 (en) * 2009-06-23 2010-12-23 Altair Engineering, Inc. Led lamp with a wavelength converting layer
US20100320922A1 (en) * 2009-06-23 2010-12-23 Altair Engineering, Inc. Illumination device including leds and a switching power control system
US20110235318A1 (en) * 2010-03-26 2011-09-29 Altair Engineering, Inc. Led light tube with dual sided light distribution
US8541958B2 (en) 2010-03-26 2013-09-24 Ilumisys, Inc. LED light with thermoelectric generator
US9057493B2 (en) 2010-03-26 2015-06-16 Ilumisys, Inc. LED light tube with dual sided light distribution
US8454193B2 (en) 2010-07-08 2013-06-04 Ilumisys, Inc. Independent modules for LED fluorescent light tube replacement
US8870415B2 (en) 2010-12-09 2014-10-28 Ilumisys, Inc. LED fluorescent tube replacement light with reduced shock hazard

Similar Documents

Publication Publication Date Title
US58105A (en) Improvement in magneto-electric apparatus
US2245781A (en) Electrical meter
US409675A (en) Stephen dudley field
US505243A (en) Recording-voltmeter
US1138103A (en) Music-player.
US692318A (en) Coin or metal detector.
US1049040A (en) Ohmmeter.
US149527A (en) Improvement in telegraph - sounders
US486689A (en) Electrical measuring-instrument
US1000074A (en) Electromagnetic switch.
US511005A (en) Telegraphic relay
US787905A (en) Telegraphic relay.
US502449A (en) Relay
US554321A (en) Electrical measuring-instrument
US1180719A (en) Three-position direct-current relay.
US41927A (en) Improvement in magneto-electric machines
US494830A (en) Ground-detector for electric circuits
US487437A (en) w aqner
US1426743A (en) Electromagnetic sound-producing device
US606449A (en) James l
US113589A (en) Improvement in electro-magnetic burglar-alarms
US898686A (en) Electric bell.
US1876483A (en) adams
US495086A (en) Voltmeter and ampere-meter
US480892A (en) Rheostat