Earth Inductor

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Instrument dealers often described this type of instrument as a Palmieri apparatus, noting that it showed that the earth's magnetic field will induce a current in a rotating coil of wire. Luigi Palmieri was a physicist in Naples who, in the 1840s, developed an earth inductor with an elliptical ring that rotated around its longer axis. The Palmieri apparatus with a circular ring seems to have originated in the 1860s. This example belonged to Princeton University and may date from the 1870s, when Princeton established a School of Science. It came to the Smithsonian in 1961.

Ref: E. Leybold, Catalogue of Physical Apparatus (Cologne, n.d.), item 6580.

Currently not on view
Physical Description
wood (overall material)
overall: 10 in; 25.4 cm
overall: 11 1/2 in x 13 3/4 in x 7 in; 29.21 cm x 34.925 cm x 17.78 cm
ID Number
accession number
catalog number
Credit Line
Princeton University
Science & Scientific Instruments
Science & Scientific Instruments
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Medicine and Science: Physical Sciences
Science & Mathematics
Data Source
National Museum of American History