Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book (1902)
Swoope, Coates Walton. [from old catalog] · New York, D. Van Nostrand company · leaf 36
Fig. 25.—Making :Magnetic Field of a Bar Magnet. nent record of the magnetic field, a piece of paraffin-coatedpaper is used in place of the cardboard. After the field is
Electricity · Magnetism
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