induction coil
Datecirca 1859
Inventory Number0343
ClassificationInduction Coil
Subject
Maker
Heinrich Daniel Ruhmkorff
1803 - 1877
User
Department of Physics, Harvard University
founded 1884
Cultural Region
Place of Origin
Place of Use
Dimensions17.5 × 52.1 × 22.3 cm (6 7/8 × 20 1/2 × 8 3/4 in.)
Material
Bibliography
DescriptionInduction coil with glass endplates, and high tension posts, ivory reversing switch. This double coil is mounted horizontally on a mahogany base that contains a concealed condenser. The coil's end pieces are glass, and both primary and secondary wires come thorough holes in the glass. Two glass posts supported the ends of the secondary wire. Apparently the contact breaker was at this end of the instrument. At the other end is an ivory (hand operated) reversing switch. Polished copper strips appear to conduct electricity from end to end on the base. The wires are insulated in a green thread. This is a particularly finely crafted induction coil.
From instrument's card:
A relatively long coil with glass "bobbin" ends through which protrude an iron core made up of iron wired and capped at each end. Secondary winding seems to be in simple layers running entire length of coil. Contact-breaker (interrupter of pre circuit) is a shoe on side of core with thumb-screw adjustments underneath (parts missing). Reversing switch of cylinder form in ivory at one end of mounting and high voltage terminals in glass rods at other. Spark distance about 1 inch. Secured to a wooden base on box containing condenser.
From instrument's card:
A relatively long coil with glass "bobbin" ends through which protrude an iron core made up of iron wired and capped at each end. Secondary winding seems to be in simple layers running entire length of coil. Contact-breaker (interrupter of pre circuit) is a shoe on side of core with thumb-screw adjustments underneath (parts missing). Reversing switch of cylinder form in ivory at one end of mounting and high voltage terminals in glass rods at other. Spark distance about 1 inch. Secured to a wooden base on box containing condenser.
Signedsigned: Ruhmkorff a Paris
Inscribedold numbers stamped: 8-63
FunctionFor experimentation and demonstration of the high voltages induced in a secondary winding when the current in the primary windings is abruptly disrupted. With this coil, the spark gap distance was about 1 ".
From card: "The uses of an induction coil are very numerous. Some of these may be classified: Experimental - production of sparks - magnetic deflection - colors from metals of spark points - perforation of solids as plate glass. Shocks - entertainment - medical. Discharges in vacuum - luminous discharge - deflection and rotation - Geissler tube in vacuum tubes - phosphoresce and florescence of materials - stratification - spectra of gases. High Vacuum effects and X-Rays (but not till 1895)."
From card: "The uses of an induction coil are very numerous. Some of these may be classified: Experimental - production of sparks - magnetic deflection - colors from metals of spark points - perforation of solids as plate glass. Shocks - entertainment - medical. Discharges in vacuum - luminous discharge - deflection and rotation - Geissler tube in vacuum tubes - phosphoresce and florescence of materials - stratification - spectra of gases. High Vacuum effects and X-Rays (but not till 1895)."
ProvenanceUsed in the Physics Department at Harvard University.
Ducretet et Lejeune
Date: 1892-1896
Object number: DW0089
