the particles oj magnetic bodies^ &c. 113 
We have as yet no facts which indicate on what function 
of the time either the developement or dissipation of mag¬ 
netism depends; and until this can be ascertained, there 
appears little prospect of obtaining a complete solution to this 
interesting but intricate problem in magnetism. It appeared 
to me not improbable, that when the distance of a magnetic 
pole from a body capable of becoming magnetic by induction, 
is suddenly decreased, the magnetism developed in any very 
small portion of time, varies as the time and the magnetism 
yet remaining to be developed, before it has attained the 
maximum intensity of which it is susceptible at this dimi¬ 
nished distance, and which may be called the intensity due 
to this distance; and that on the contrary, on the removal of 
the pole, the magnetism dissipated varies as the time and the 
excess of the intensity above the minimum at the increased 
distance; the rate of developement and dissipation not being 
however, cceteris paribus, necessarily the same. I accordingly 
assumed this, in order to obtain the intensity of the mag¬ 
netism in any point of the ring in terms of its distance from 
the pole of the magnet; but although the differential equa¬ 
tion that would result from this assumption is integrable, so 
that the intensity of the point may be determined, yet as it is 
in a series whose convergency depends upon the smallness 
of the angular distance between that point and the point 
vertically over the pole of the magnet, and a second inte¬ 
gration is required to deduce the force with which the mag¬ 
nets urge the ring, the result is rendered so complicated, 
that to reduce it to any form with which the formula I have 
obtained from experiment may be compared, appears almost 
a hopeless task. I consider therefore that, in ojrder to obtain 
Q 
MDCCCXXVII. 
