404 Electro-Magnetic Experiments. 
satisfaciory explanation ef the phenomena of magnetic rotation. No 
detail is given of the experiments, and it is somewhat surprising that 
results so interesting, and which certainly form a new era in the his- 
tory of electricity and magnetism, should not have been more fully 
described before this time in some of the English publications; the 
only mention I have found of them is the following short account 
from the Annals of Philosophy for April, under the head of Pro- 
ceedings of the Royal Institution. 
“ Feb. 17.—Mr. Faraday gave an account of the first two parts 
of his researches in electricity; namely, Volta-electric induction and 
magneto-electric induction. If two wires, A and B, be placed side 
by side, but not in contact, and a Voltaic current be passed through 
A, there is instantly a current produced by induction in B, in the 
opposite direction. Although the principal current in A be con- 
tinued, still the secondary current in B is not found to accompany it, 
for it ceases after the first moment, but when the principal current is 
stopped then there is a second current produced in B, in the oppo- 
site direction to that of the first produced by the inductive action, 
or in the same direction as that of the principal current. ; 
‘“‘1f a wire, connected at both extremities with a galvanometer, be 
coiled in the form of a helix around a magnet, no current of electri- 
city takes place in it. ‘This is an experiment which has been made 
by various persons hundreds of times, in the hope of evolving elec- 
tricity from magnetism, and as in other cases in which the wishes of 
the experimenter and the facts are opposed to each other, has given 
rise to very conflicting conclusions. But if the magnet be withdrawn 
from or introduced into such a helix, a current of electricity is pro- 
duced whilst the magnet 1s in motion, and is rendered evident by the 
deflection of the galvanometer. Ifa single wire be passed by a mag- 
netic pole, a current of electricity is induced through it which can be 
rendered sensible.”’* 
Before having any knowledge of the method given in the above 
account, I had succeeded. in producing electrical effects in the fol- 
lowing manner, which differs from that employed by Mr. Faraday, 
and which appears to me to develope some new and interesting facts. 
A piece of copper wire, about thirty feet long and covered with 
elastic varnish, was closely coiled around the middle of the soft iron 
armature of the galvanic magnet, described in Vol. XIX of the 
American Journal of Science, and which, when excited, will readily 
* This extract will also be found on page 386 of this Journal—Zd. 
