Flame, electricity and the camera; man's progress from the first kindling of fire to the wireless telegraph and the photography of color (1900)
Iles, George, 1852-1942 · New York, Doubleday & McClure co. · leaf 135
selves in concentric curves instead of in radiallines (Fig. 3 1). Sturgeon, in 1824, advanced matters by an importantstep as he discriminated between the magnetism of steeland that of soft iron. He noticed that soft iron was mag-netic only while in contact with a steel magnet; whenhe severed them… … Fig. 29. Electric solenoid pole {A) attracted bydissimilar pole (B) of bar magnet.
Technology · Fire · Electricity · Photography
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