310 Proceedings of Royal Society of Edinburgh. [sess. 
The above results may be equally well illustrated if transverse 
induction be plotted not against H for various values of 6 , but 
against 0 increasing from 0° to 90° for various values of H. If the 
values of H be low, the curves for both metals appear to reach 
their maxima when 0 is approximately equal to 45°. If, however, 
H be taken higher, maximum values are rapidly displaced to the 
left, the curves rising very abruptly between 0° and 15°. In 'iron, 
on the other hand, this displacement occurs slowly, and is (within 
present experimental limits) much less in amount. 
The above experiments were made with hollow cylinders, so 
constructed that the shell of each cylinder was itself hollow. Or, 
they may be described as hollow anchor rings flattened so that the 
difference between the internal and external radii was less than 1 
in 10. The width of each hollow ring was made nearly equal to 
7 r times its average radius. The smallness of the transverse effect 
in nickel necessitated the elimination of the demagnetising effect 
of the ends of the hollow cylinders previously used. 
I take this opportunity of acknowledging my indebtedness to 
the Royal Society of London for placing at my disposal a Govern- 
ment grant for the purposes of this research. 
( Issued separately August 22 , 1904 .) 
