Cumming, Linnæus, b. 1843. [from old catalog] · New York, D. Van Nostrand · leaf 308
Fig. 186. This commutator is used in a great number of electro-magnetictoys. On placing it axially between the poles of a permanentmagnet, a short electro-magnet (Fig. 187, a), whose terminalsdip into the commutator cup, can be made to rotate withgreat rapidity. If the partition be placed in the…
Electricity
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