154 Prof. A. dé la Rive’s Memoir of . 
and of which a description was previously nowhere to be found, 
so that every one was obliged to undergo an apprenticeship to 
them on hig own account. It was necessary that a savant who 
for so many years had been struggling with the difficulties of 
experimentation, and who had been able to surmount them in 
so ingenious a manner, should give himself the trouble to de- 
scribe the means which he hademployed, so that his experience 
might be of service to others. Faraday was this savant, and 
his object was completely attained. 
Here, perhaps, before proceeding to another set of subjects, 
we ought to speak of certain of Faraday’s theoretical ideas 
relating to general physics, and more especially to the nature 
of the forces, and their correlation to each other and to the es- 
sence of matter; but we prefer not to discuss the opinions 
emitted by him upon these questions until after the exposition 
of his works on electricity and magnetism. We must, how- 
ever, at once admit that his views on these matters are very 
contestable, and that, if they inspired him to make experimen- 
tal researches of the highest interest, this is a proof that, in 
the hands of a man of genius even a bad theory may be the ori- 
gin of the most beautiful discoveries. 
Il. 
completed. Each memoir certainly forms a complete whole; 
but one memoir is most frequently followed by another, the 
subject of which is quite different. It seems as if the author, 
after having treated one question, found it necessary to reco. 
himself before resuming it, and to divert his mind from 1t, 80 
tos . ing up some other kind of work. __ 
_ It has therefore a to me that the best thing for me 
to do, was to group all these various works under a few distinct 
heads, so as to be able to give their essence without requiring 
to enter into too many details, The first would include all 
— relating to electrochemistry; the second, those 
which have for their object induction, whether electrodynami¢ 
eS 
all 
