131 
intermediate state, not neutral, but sluggish (for a more 
elegant term has not yet been suggested.) I cannot conceive 
any manner in which we may account for such assumption 
of the sluggish state according to Ampere's theory, unless 
we suppose two currents in opposite directions in the same 
piece of metal, and at the same time ; a supposition which 
is contrary to all observed phenomena or laws of electric 
currents. We should, nevertheless, have some difficulty 
in explaining the effects produced, for under whatever cir- 
cumstances we have hitherto observed the production of 
such currents, we find that they are transient, and only 
continue during such time as the inducing force is either 
increasing or diminishing. We find, on the contrary, that 
the magnetic force does not in general rise to its maximum 
until after the lapse of a longer period of time than an 
electric current, induced under similar circumstances, would 
have continued. This consideration becomes still more 
forcible in regarding the phenomena exhibited by zinc, 
under the influence of forces which are little more than 
sufficient to render it dia-magnetic. The zinc is at first 
attracted as magnetic, but slowly becomes dia-magnetic, 
appearing to pass through an intermediate state, in which 
it appears very little sensible to either attraction or repul- 
sion. We have also to consider the phenomena of revulsion, 
which might be explained by the hypothesis of induced cur- 
rents, if the revulsion always took place in the like manner 
and direction. The revulsion is sometimes attractive, and 
sometimes repulsive; if, therefore, these phenomena be due 
to induced electrical currents, such currents must be in 
different directions. I have, however, pointed out that the 
phenomena of revulsion are intimately connected with elec- 
trical currents, as the revulsive effects are not exhibited 
with the insulated disc of wire, in which the completion of 
a circuit is prevented. On these, and similar considera- 
