liv REPORT—1852. 
beneath the surface, or in the atmosphere above the surface, are separated 
by a wide interval from the solstitial epochs, appears to favour the hypothesis 
of a direct action; as does also the remarkable fact which has been established, 
that the magnetic force is greater in both the northern and southern hemi- 
spheres in the months of December, January, and February, when the sun 
is nearest to the earth, than in those of May, June, and July, when he is 
most distant from it: whereas if the effects were due to temperature, the two 
hemispheres should be oppositely instead of similarly affected in each of the 
two periods referred to. Still there are doubtless minor periodical irregular 
variations yet to be made out by suitable analytical processes, which, by 
their possible accordance with the epochs of maximum and minimum 
temperature, may support in a more limited sense, not as a sole but as 
a coordinate cause, the hypothesis of calorific agency so generally received, 
and so ably advocated of late in connection with the discovery by our great 
chemist and philosopher of the magnetic properties of oxygen and of the 
manner in which they are modified and affected by differences of temperature. 
It may indeed be difficult to suppose that the magnetic phenomena which 
we measure at the surface of the globe, should not be in any degree influ- 
enced by the variations in the magnetic conditions of the oxygen of the 
atmosphere in different seasons and at different hours of the day and night ; 
but whether that influence be sensible or not, whether it be appreciable by 
our instruments or inappreciable by them, is a question which yet remains 
for solution by the more minute sifting of the accumulated facts which are 
now undergoing examination in so many quarters. 
To justify the anticipation that conclusions of the most striking character, 
and wholly unforeseen, may yet be derivable from the materials in our 
possession, we need only to recall the experience of the last few months, 
which have brought to our knowledge the existence of what may possibly 
prove the most instructive, as it is certainly at first sight the least explicable, 
of all the periodical magnetic variations with which we’ have become ac- 
quainted. I refer to the concurrent testimony which observations at parts 
of the globe the most distant from each other bear to the existence of a 
periodical variation or inequality, affecting alike the magnitude of the diurnal 
variations, and the magnitude and frequency of the disturbances or storms. 
The cycle or period of this inequality appears to extend to about ten of our 
years; the maximum and minimum of the magnitudes affected by it being 
separated by an interval of about five years, and the differences being much 
too great, and resting on an induction far too extensive, to admit of uncer- — 
tainty as to the facts themselves. The existence of a well-marked magnetic 
period which has certainly no counterpart in thermic conditions, appears to 
render still more doubtful the supposed connexion between the magnetic and 
calorific influences of the sun. It is not a little remarkable that this periodical 
magnetic variation is found to be identical in period and in epochs of maxima 
and minima with the periodical variation in the frequency and magnitude of 
