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 Induction Coils

The principle of electromagnetic induction was discovered by Michael Faraday (1791-1867) in 1831. Induction coils were used widely in electrical experiments and for medical therapy during the last half of the 19th century, eventually leading to the development of radio in the 1890's. For more information on the application of induction coils in radio, see my chapter on spark coils in the "The Wireless Age" section of this web site.

An induction coil essentially operates like a big buzzer: The interrupter's contacts (C), are wired in series between the battery (B), and the coil. The contacts are closed in their resting state. When power (B) is applied, the coil is activated which produces a magnetic field at the metal core of the coil. The magnetic contact arm (V) is pulled toward the core, opening the interrupter contacts and breaking the circuit. The falling magnetic field relaxes its hold, the contacts close, and the entire cycle repeats.

The rising and falling magnetic field of the primary coil induces a high voltage across the secondary.

How They Were Used
Induction coils were used in many different kinds of experiments. In order to facilitate easy access to a variety of devices, an experiment table was commonly used. A typical table is shown at the right. The output of the coil was connected to the vertical brass uprights and the connections could be adjusted safely using the insulated handles.

The "hand electrodes" shown in the photo were used in experiments where the output of the coil was connected to a person (not directly - through a rheostat!) Many people of the time believed the mild electrical shock to be therapeutic. An entire industry of "quack" medical devices was born from the invention of the induction coil.


8" Experiment Table

A specialized type of induction coil called a Rhumkorff coil was used in early radio transmitters  - so called "Spark" transmitters in the "teens".  You can see some examples of these spark coils by clicking here.

 


High Voltage Experiment Table
and Hand Electrodes
1868

 


Henly's Universal Discharger
J. Newman, Lisle Street, London
1st Qtr, 19th Century

 Mahogany base measures 15" x 6"; the glass pillars are 8-3/4" in height. See Public and Private Science: The King George III Collection pg 520, fig. E213.


Grenet Cell
1885

Powering an Induction Coil
The photo at left is of a Grenet cell. These early acid jar batteries was used widely in electrical experiments during the last quarter of the 19th century and  were commonly used as the primary power source for induction coils. For more information and a photo of Thomas Edison using the cell, click here.

 

Some other examples of induction coils in my collection are shown below.

 


Griggs Conical Electromagnetic Machine
1873


Griggs Machine
Label


Rhumkorff coil (signed)
1850

William Sturgeon Mercury Interrupter
English
1838

Described in "Annals of Electricity, Magnetism and Chemistry" Vol. III, London 1838 pgs 331-334, Plate Il figs. 15 and 16.

 

William Sturgeon Mercury Interrupter
English
1830

Primitive Hand-wound Interrupter
English
1840

The brass and ivory handle turns a cogged wheel and the axle of a double ratchet, which engages the cogs is connected to a horizontal copper bar. The axle and the ends of the horizontal bar are bent to dip in mercury cups. On rotating the crank handle, the pinion wheel causes the bar to execute a rapid see-saw movement which then causes the end pieces to make and break contact rapidly with the measuring in the two side cups. Described in The Scientific Apparatus of Nicholas Callan , Mollan and Upton, 1994 pg. 84-85, fig. 102. .

Compound Magnet and Electrotome
Daniel Davis
1840


 
Invented by Charles Page in 1838 (see Page's biography: Physics, Patents and Politics by R.C. Post pg. 24) but patented in 1868. First described by Page in "Magneto-Electric and ElectroMagnetic Apparatus and Experiments, " American Journal of Science, (1839), pgs 252-68, figs. 1-7.

 

 

Double Helix and Vibrating Electrotome
Daniel Davis
1848


Described in slightly different form in Manual of Magnetism pg 301 fig. 182. (2nd Ed). Invented by Charles Page and patented in 1868 but developed in 1838.

"Dr. C.B. Barrett Medico Electro-Medical Machine"
Likely Daniel Davis
1848


Pictured and described in Manual of Magnetism (pg. 301 fig. 182)

 

Double Helix and Vibrating Electrotome
Daniel Davis
1842

This is a larger version described in Davis's Manual of Magnetism pg. 301 fig. 182 (2nd Edition). Included are two rosewood and brass medical shock handles and battery (some paint worn off) as shown in Davis's Catalog pg. 38, fig 182.

Hinds and Williams Double Helix and Vibrating Electrotome
Likely Daniel Davis
1848

 (See pg. 301, fig. 182 of Davis' Manual of Magnetism 2nd Edition. )

 

Pike's Vibrating Magnetic Instrument for Medical Use
Benjamin Pike, Jr.
1848

Signed by Benjamin Pike, Jr., on bottom of mahogany base with trade card reading "Benjamin Pike, Jr., Optician, Importer and Manufacturer of Mathematical and Philosophical Instruments, No. 294 Broadway, New York".  This machine is described in Pike's Catalog, on pg. 47 of Volume II, fig. 469.

PIKE'S ROTARY MAGNETIC MACHINE
Benjamin Pike, Jr.
1848

An electromagnetic machine and battery and with trade card attached to inside cover of walnut box measuring 16" x 6" x 7". Trade card reads "Benjamin Pike, Jr. Optician, Importer and Manufacturer of Mathematic and Philosophical Instruments, No. 294 Broadway, New York". Elaborate label also an inside top lid of box reads "Pike's Rotary Magnetic Machine introduced Nov. 1843 " with extensive instruction on use.

This machine is described in Pike's Catalog Vol. II on pages 44- 47 and pictured in fig. 468. The device is featured on the front wall (in a large advertisement) of Pike's first shop in 1848 as seen in the woodcut frontispiece in his catalogs of 1848 and 1856.

 

"DR. S.B. SMITH'S 18 POUND MAGNETIC CURRENT AND 6 POUND DIRECT CURRENT MACHINE"
1845

Box made of walnut measuring 6" x 3-1/2 " with electromagnetic machine and accessories. Label of inside cover reads "Dr. S.B. Smith's Pocket Magnetic machine of very strong Intensity" with instructions.

NEW PORTABLE MAGNETO-ELECTRICAL MACHINE FOR MEDICAL PURPOSES
Benjamin Pike, Jr.
1848

 Described in Pike's Catalog Vol. II pg. 49 fig. 471.

 

NEW PORTABLE MAGNETO-ELECTRICAL MACHINE FOR MEDICAL PURPOSES
Benjamin Pike, Jr.
1848

Described in Pike's Catalog Vol. II pg. 49 fig. 471

"DR. S.B. SMITH'S DIRECT AND TO-AND-FRO CURRENT ELECTRIC MACHINE"
1850.

 

FOSTER'S IMPROVED ELECTROTOME,
"James Foster, Makers, Cincinnati, O"
1850

Has green label with instructions on inside lid of mahogany box measuring 7-1/4" x 7". Electromagnetic medical device with separate glass and wood battery also signed. Fine condition; box has been restored.

ELECTROMAGENTIC MEDICAL MACHINE
 "Manufactured for G.M. Boardman by William Mead 409 Broad Street, Newark, N.J."
1840's

Contained in_ wooden box measures 6-1/2" x 6" x 3-1/2" with primitive copper-zinc battery.
 

Double Helix and Vibrating Electrotome Complete with Battery and Handles in Wooden Box
N.B. Chamberlain
1840's

 Identical to Davis set on pg. 301, fig. 182 in the Manual of Magnetism.  Extremely rare in it's completeness..

"DR. C.B. BARRETT MEDICO ELECTRO-MEDICAL MACHINE"
New York, 1848

  Pictured and described in the Manual of Magnetism pg. 301, fig. 182 and likely made by Davis but signed by "Barrett".

 

JEROME JEWELL: ELECTRO-MEDICAL DOUBLE HELIX AND RECIPROCATING ARMATURE ENGINE
1848

A fine and early reciprocating engine with four poles mounted atop the helix instead of a vibrating electrotome. Clearly in the style of Daniel Davis with typical components, including four brass ball feet supporting the base. Signed. "Jerome Jewell, Manufacturer of Galvanic Instruments, Bristol, Conn.

Double Helix and Vibrating Electrotome
Daniel Davis, Jr.
1840's

Missing a finial. Illustrated in the Manual of Magnetism on pg. 301, fig. 182.
 

"DR. S.B. SMITH'S DIRECT AND TO-AND-FRO CURRENT AUTOMATON ELECTROMAGNETIC MACHINE"
New York, Patented June 4, 1850

The electromagnetic device measures 7-3/4" x 3" and instead of an electrotome as the interrupter, this device has a rotating engine similar to "Pike's Rotary Magnetic Machine"

A36

 

 

"DR. S.B. SMITH'S TORPEDO MAGNETIC MACHINE"
1840's

 Label on inside cover reads "Dr. S.B. Smith's Torpedo Magnetic Machine" and shows a horse and buggy in front of Dr. Smith's establishment. . A primitive battery is included in the box as well.

"HINDS AND WILLIAMS, MANUFACTURER'S OF APPARATUS TO ILLUSTRATE MAGNETISM, GALVANISM, ELECTRODYNAMICS, ELECTROMAGNETISM, MAGNETO ELECTRICITY, THERMOELECTRICITY, NO. 313 WASHINGTON STREETS, BOSTON, MASS"
1850

A  vibrating electrotome and double helix complete in walnut box measuring 10" x 7"x 7" with purple backed label with gold lettering as above on inner lid. The electromagnetic instrument measures 4-1/2" x 6-1/2" rosewood base, the green painted circular battery is 4-1/4" (d) and 6" (h). Accessories include: electro-shock handle; an electromagnetic glass eye-cup and a natural sponge.

 

Double Helix and Vibrating Electrotome
C. Williams, Boston
1860

Very similar to above "Hinds and Williams" except missing inner label to box. Battery is missing, accessories include rosewood electromagnetic eye-cup and two rosewood electro-shock handles. The electromagnetic device is on a walnut base and measures 6-5/8" x 4-1/2" and is stamped "C. Williams, Boston" on brass support straps holding coil which is painted red.

VIBRATING MAGNETIC MACHINE
 signed "H.H. Sherwood, M.D."
1840's
 

Pictured and described in the Manual for Magnetizing with the Rotary and Vibrating Magnetic Machine in the Duodynamic Treatment of Diseases, by H.H. Sherwood, M.D. (9th Ed), New York, 1847 on page 31.

 

A45

VIBRATING MAGNETIC MACHINE,
signed "H.H. Sherwood, M.D."
1840's

Identical to coil at left except with brass attachments to binding posts leading to wire to connect to electromagnetic shock handles.

BOX OF EARLY ROSEWOOD-HANDLED ELECTROMAGNETIC MEDICAL ACCESSORIES
American.
1840's - 1850's

Pictured and described in Illustrated Catalog of ElectroMedical Instruments Manufactured and sold by Thomas Hall, Boston, 1864 on pages 19-23. Contained neatly in a mahogany box measuring 13-1/2" x 6-1/2" x 2-1/2" are six fine rosewood and brass electromagnetic medical accessories including two adjustable rosewood eye cups. A very rare and unusual set, likely earlier than the one pictured in the above catalog.

 

ELECTRICAL BELT
signed "Pulvermacher Galvano Co. Electricity is Life"
American
1880's

 In black cloth covered box measuring 8-5/8" x 61-3/8" (h) and accompanied with instruction book and catalog by the Pulvermacher Galvano Company. Belt is made of a brass weave.

S.B. SMITH “PREMIUM’’ ELECTROMAGNETIC MEDICAL MACHINE
1850’s

 

VERY EARLY “PIKE AND SON’ ELECTROMAGNETIC MEDICAL MACHINE,
“Pike and Son”
1842

ELECTROMAGNETIC MEDICAL DEVICE
Benjamin Pike, Jr.
1848

 In box with shock handles, box with extensive instructions and labels from Benjamin Pike on inside cover, fig 472, pg 52 of Pike’s Catalog

 

COMPOUND MAGNET AND ELECTROTOME
Daniel Davis
1840's


Jumbo style version of this instrument invented by Charles Page.

     

 

 


Griffin & George Rhumkorff
Coil


Rhumkorff Coil
c. 1900


English Induction Coil
4th Qtr 19th Century

 


French Induction Coil
c. 1870


English Induction Coil
4th Qtr 19th Century
 


Rhumkorff Coil
c. 1870


Laboratory Induction Coil
1900


Unmarked Induction Coil


Small Lab Induction Coil


Knott Vertical Laboratory Induction Coil

 


Early Induction Coil
1840's

 

   
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