210 
Proceedings of the Royal Society of Edinburgh. [Sess. 
The values of R calculated from these expressions for the various fields 
involved are inserted in Table B for comparison with the observed values. 
The agreement is good, except perhaps for the lowest transverse field. The 
formulae, of course, apply only within the limits of the fields used in the 
experiments. 
In these experiments with the nickel strip I did not obtain an increase 
of resistance in the lower transverse fields, such as was observed by 
Grunmach (4) and Heaps (5) in their experiments with nickel wires. The 
transverse fields to which they had to subject their fine wires were as a rule 
much higher than the fields which I was able to get with my arrangement. 
The range of value of the transverse fields which I used corresponds 
nominally with the fields below 700 or 800 with which they obtained in 
general an increase of resistance. In their experiments the decrease of 
resistance did not set in to any marked degree till field 1000 was exceeded. 
Both these experimenters used very thin nickel wires ; and it was not till 
the transverse field reached the value of 2000 or 3000 that the decrease of 
resistance was of the same magnitude as that obtained in my experiments 
with the nickel strip. It was indeed with the object of increasing the 
magnetic induction in transverse fields that I chose the strip instead of the 
otherwise more convenient wire. It is interesting to remember in this con- 
nection that in his early experiments Kelvin used thin plates and not wires. 
Thus we see that, just as the magnetization itself depends upon the 
form of the material in a given magnetic field, so in regard to the change 
of resistance in a transverse field the width in the direction of the 
magnetizing force is an important determining factor. 
These comparisons show that I am here dealing with a phenomenon 
which is only in a broad and general sense similar to that which was 
being studied by Grunmach about the same time. The immediate object 
of my experiments was not, however, to study the relation between 
resistance and magnetization, but to study the interplay of the two 
mutually perpendicular fields in their effect on resistance. I now pass to 
the consideration of this effect of the two cross magnetizing forces in 
various combinations. 
I shall choose for detailed discussion one of the forty-seven complete 
groups of experiment given in Table A, say, the one corresponding to 
longitudinal field 47*4 and the transverse field 170. This combination is 
conveniently represented by the symbol V. 3, V. referring to the fifth 
group and three to the third column. In this group V. 3 the values of the 
changes of resistance per 10,000 are 
H= +58, T = -65, H(T)= +13, T(H) = - 124. 
