122 Scientific Proceedings, Boyal Dublin Society. 



and when the load on the wire is increased 2-43 times, the decrease of circular 

 magnetism is about 60 per cent, for the same range of field variation. 



7. When the load per unit ai'ea, the longitudinal magnetism, and the 

 current density in iron wires are kept constant, the maximum twist of the 

 free end of the wire increases with the cross-sectional area of the wire up 

 to about 20'6 x IC sq. ems. In a magnetic field of 0'45 c. g. s. units, 

 when the cross-sectional area of the wire is increased b\ times, the maximum 

 twist on the wire is increased 9 times ; and in a field of 7 c. g. s. units the 

 maximum twist is increased about If times for the same change in the 

 wire's cross-sectional area. 



