... Given two magnets, Gilbert knew that magnetic poles can attract or repel, depending on polarity. ... That is, the end of an iron bar stuck to an S pole of a magnet (south-seeking pole) temporarily becomes an N-pole. ... Gilbert confirmed his guess of temporary ("induced") magnetism by an original experiment (see drawing). ... Under the influence of the terrella, each became a temporary magnet with the same polarities, and the temporary poles of each bar repelled those of the other one. ...