inery for lighting and power has as- interest, being peculiar to this machine. They are sumed gigantic proportions, and its extended applica- wound with square copper wire and insulated with machine. tion in other directions, especially in mining, is increas- pure India mica placed between turns… … : ars the oldest mines in this coils is such as to always magnetize the plunger one Fig. 2.—LONGITUDINAL 8EC- country. This mine was way. The magnetism is, in other words, never re- TION OF THE MARVIN once famous for its nick- versed. Likewise the dynamo field is overcompounded ROCK DRILL. el and…
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