66 W. A. Norton on Molecular Physics. 
At the epochs for which n was an uneven number, two sys 
tems of currents should have been developed, one at each equi- 
nox, and the intensity of each of these would have been muc 
less than that of the single system (the sum of the two equi- 
noctial systems), answering to the epoch when » was an even 
umber. These separate systems of currents should, therefore, 
by reason of their secular movements, have tended to become 
incorporated with the other more effective ones, which would 
have been displaced more slowly. 
t will be seen, in another connection, that the magnetic state 
of the earth experiences certain changes, from year to year,—in 
response to the varying magnetic and electric condition of the 
sun’s surface. We may then conclude, from our present point 
of view, that the existing system of magnetic currents should 
bear the traces not only of the changes through which the mag- 
netic condition of the earth has passed, but also of the mighty 
changes that have passed over the face of the sun. 
rom our present point of view we may discern the probable 
link of connection between the magnetism and the temperature 
of the earth. In the paper already referred to (p. 63) a mathe- 
matical exposition was given of the formal relations subsisting 
between the principles of magnetism and heat in the crust of the 
earth, based upon certain mechanical ideas. We have already 
seen (p. 64) that the fundamental ideas then assumed are in 
essential accordance with the present theory of the origin of 
terrestrial magnetism. It may now be added that the mathe- 
matical relations shown to subsist, between the intensity of the 
magnetic action and the temperature, may be seen to have a 
phyeicet basis. The dependence here alluded to arises from the 
t that the electric currents developed by the impulsive action 
of the ether of space, within the crust of the earth, must, to a 
certain extent, pass off in the form of heat; and that the earth 
ant currents traversing the localities. It will be readily seen 
that, the inequalities of the mean temperature of the crust of 
is 3 from | 
elevation, &c., and from variations in the intensity of the result- 
tirely correspond; thatthe 
poles of greatest cold would coincide with the magnetic poles, 
e ical Varia 
lished in this Jo 
show that 
