100 
MESSRS. G. F. C. SEAELE AND T. G. BEDFORD 
-4 
leaks out from the wire by the cylindrical surface, thus developing a distribution of 
magnetism along the wire, Iiq is considerably greater than it would be were the “ poles ” 
at the ends of the wire. As Bq increases, Iiq increases less rapidly, reaches a maximum 
for a value of Bg [10300] somewhat greater than B'q [8400], the value corresjDonding 
Fig. 18. 
to fx' the maximum value of p, and then diminishes. As B,, increases still further, 
/?o diminishes rapidly till Bq reaches the stage where p begins to diminish compara¬ 
tively slowly. After passing a minimum /i,, again increases, and in this last stage 
is less than 2 IqA//^. 
§76. The expeiiments of Mr. C. G. Lamb, “On the Distribution of Magnetic 
Induction in a Long Iron Bar,”"^' serve to explain the rise of /;q to a maximum, and its 
subsequent fall. For he found that as Bq increases from zero, the percentage of the 
induction at the centre of the rod which leaks out between the centre and the end of 
* ‘Proc. Phys. Soc.,’ vol. 16, p. 509; or ‘Phil. Mag.,’ Sept., 1899. 
