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Scientific Proceedings, Roijal Dublin Societ/j. 



wire tested in tliis way would exhibit loops of hysteresis iu the same way as 

 in the ordinary B-H curve for iron.' In order to test this, a carefully 

 annealed No. 16 iron wire of cross-sectional area, 20"6 x 10"' sq. cms., was 

 suspended inside the solenoid, whicli was arranged to give an internal longi- 

 tudinal magnetic field of 2'5 c.g.s. units; the longitudinal stress or load 

 on the end of the wire being that of tlie vibrator only, viz., 0'34 x 10* 

 grammes per sq. cm. A complete cycle was taken in which the increments 

 of current through the wire were small — so as to get numerous points on tlie 

 curve — the maximum value being 2-06 amperes. During tlie cycle two 

 hysteresis-loops were obtained ; and the values for the cycle and loops are 

 given in Table III., and shown as curves in fig. 5 . 



Table III. 



' Ew'ing's " Magnetic Induction in Iron and other Metals," 3rd ed., p. 95. 



