Experimental science. Elementary, practical and experimental physics (1890)
Hopkins, George M. (George Milton), 1842-1902 · New York, Munn & co. · leaf 371
Development of M.ignetism by Torsion. and striking it several blows on the end with a hammer,it becomes permanently magnetic, not strongly, but suffi-ciently to exhibit polarity when presented to a magneticneedle. By twisting a rod of soft iron having one of its ends in Fig. 332. . Fig. 333.
Physics · Lantern projection · Electric apparatus and appliances
Internet Archive · Cornell University Library · Public Domain Mark 1.0. Free to use for anything.
