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 18
dle points is calledthe positive direction of the lines of magnetic force, and the directionin which the south pole points, the negative direction of the lines ofmagnetic force. Lines of magnetic force are said to run from the north pole of themagnet to the south pole through the air, and back to… … Fig. 8. the battery connections, a field of magnetic force which can be exploredby a small magnetic needle, or outlined by iron filings, as in fig. 6,will be found to exist around the spiral, and the direction of the lines offorce will be found the same as those around the magnet in fig. 7. If…
