^08 



Scientific Proceedings, Roi/al Dublin Society. 



The curves show that the longitudinal load on the wire being constant, the 

 longitudinal magnetic field in which the maximum twist occurs is independent 

 of the length of the wire. 



O 20 4-0 60 



Magnetic Field H. 

 Fig. 3, — Wire with the temper and load constant, and varying length. 



If we plot the values of the length of the wires as abscissae, and as 

 ordinates the corresponding values of the twist, for any longitudinal 

 magnetic field, the points will be found to lie very approximately in a 

 straight line in each ease ; and these straight lines when produced pass 

 through the origin, which sliows that the twist is directly proportional to the 

 length of the wire. If for the three different lengths we plot the values of 

 the load as abscissae, and as ordinates the corresponding values of maximum 

 twist, the points in each of the three cases will be found to lie in a straight 

 line. These three straight lines when produced cut the axis of ordinates at 

 different points, which points indicate the values of the maximum twist 

 which would be obtained if the wire were tested with no load on it, thus : — 



