PHILOSOPHICAL 
TRANSACTIONS. 
XIII. On a new phenomenon of electro-magnetism. By Sir 
Humphry Davy, Bart. Pres. R. S. 
Read March 6, 1823. 
On a subject so obscure as electro-magnetism, and con- 
nected by analogies more or less distinct with the doctrines 
of heat, light, electricity, and chemical attraction, it is not dif- 
ficult to frame hypotheses ; but the science is in a state too 
near its infancy to expect the developement of any satis- 
factory theory ; and its progress can only be ensured by new 
facts and experiments, which may prepare the way for ex- 
tensive and general reasonings upon its principles. Influenced 
by this opinion, I am induced to lay before the Society an 
account of an electro-magnetic phenomenon I observed about 
fifteen months ago in the laboratory of the Royal Institution, 
and which I have lately had an occasion of witnessing in a 
more perfect manner, through the kindness of Mr. Pepys, 
by the use of a large battery, constructed under his direc- 
tions for the London Institution, and containing a pair of 
MDCCOXXIII. X 
