Robison's Manual of radio telegraphy and telephony for the use of naval electricians (1918)
Robison, S. S. (Samuel Shelburne), b. 1867, United States Naval Institute, Todd, David Wooster, Hooper, Stanford Caldwell · Annapolis, Md. : The United States Naval Institute · leaf 17
south pole the negative pole of the magnet. Wrought or soft iron can be magnetized but only retains its magnet-ism while under the influence of the magnetizing force; steel or hardiron once magnetized retains its magnetization permanently, and specialmeans to demagnetize it are required. All bodies…
