232 Intelligence and Miscellaneous Articles. 



use of the term Oligocene in this country is advocated on the 

 ground that by its adoption only can we avoid the inconvenient 

 course of dividing the nuvio-marine series between the Eocene and 

 the Miocene. 



XXXI. Intelligence and Miscellaneous Articles. 



ON INTERMITTENT CURRENTS AND THE INDUCTION-BALANCE. 

 To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 

 T\7LTH reference to my communication on the subject of the 

 ' * Induction-Balance in your last issue, will you permit me to 

 add a word in order to avoid any possible misunderstanding with 

 reference to section 1. 



I have there rather unguardedly spoken of the induction-balance 

 as if I considered that all Prof. Hughes had done was to apply 

 a telephone to it. I by no means intended to convey this 

 impression. Of course it is perfectly true, and Prof. Hughes 

 himself points it out (Phil. Mag. July 1879), that induction-currents 

 had been balanced by a double pair of coils by both Dove and 

 Pelici some time ago ; but, nevertheless, the induction-balance as 

 devised by Prof. Hughes must be regarded as an essentially new 

 instrument ; for no one could have obtained the same effects from 

 the old " differential inductor" of Dove without enormous modi- 

 fication. 



Soon after hearing of Prof. Hughes's discovery, I tried to obtain 

 his effects with numerous coils which happened to be accessible in 

 University College Laboratory, varying the conditions in several 

 ways ; and I experienced the most uniform failure in getting a 

 good "balance" (that is, perfect silence in the telephone) until I 

 abandoned all of them and imitated Prof. Hughes's arrangement 

 and dimensions very closely. A " balance," in fact, is a very 

 difficult thing to obtain with such a detector in the circuit as a 

 telephone; for it is influenced not only by the least want of 

 equality, but also by the least want of synchronism between the 

 two opposing electromotive forces. 



Pew persons, therefore, can appreciate more highly than I do 

 the unremitting toil which Prof. Hughes must have devoted to his 

 experiments, before contriving the induction-balance and sonometer 

 in their present form. 



I am, Gentlemen, 



Tour obedient servant, 

 Oliver J. Lodge. 



ON THE CARRYING-POWER OF MAGNETS. BY PROF. J. STEFAN. 



In the calculation of the carrying-power of magnets three 



forces are to be distinguished : — 1, the attraction of the magnetic 



masses on the contact-surfaces of the magnet and armature ; 2, the 



actions at distance which those masses undergo from the free 



