188 



Scientific Proceedings, Royal Dublin Society. 



fig. 1. In the table the column marked D.C. contains the results obtained 

 with direct magnetic fields, and the columns marked A.C. the results for 

 alternating fields of frequencies 25 and 50 cycles per second. In fig. 1 the 

 two curves refer to the D. C. results, and the A.C. for a frequency of 50 per 

 second. In all cases the Young's Modulus is expressed in dynes per sq. 

 centimetre. 



Table I. 

 Load = 10 s grammes per sq. cm. 



From the values in column 2 of Table I, and the curve marked D.C. 

 in fig. 1, it will be seen that the modulus attains its minimum value in a 

 magnetic field of about 23 c.g.s. units. This, in a way, is confirmed by the 

 results obtained by Honda and Terada, because, if the constant loads on 

 the wire be plotted as abscissae, and as ordinates, the corresponding magnetic 

 field in which the minimum modulus occurs, it will be found that the three 

 points obtained by these experimenters and the one point obtained by the 

 present writer all lie very approximately oil a straight line. 



The change in the Young's modulus is small for both direct and alter- 

 nating fields, being for direct fields decreased a little under 4 per cent, 

 between no field and a field of 23 units where the minimum occurs ; it then 

 increases a little under 3£ per cent, between the fields of 23 and 80 units. 



