NOTE ON THE TOTAL ECLIPSE OF THE MOON. 169 ’ 
the foregoing extract, its inadequacy may, I think, be shown by 
the following considerations. 
The portion of the earth’s atmosphere through which the 
solar rays will pass to reach the moon will clearly be an entire 
ring, embracing almost all varieties of terrestrial climate. It 
is inconceivable that there should be anything approaching to 
uniformity in the hygrometric condition of this atmospheric 
ring. It is almost equally inconceivable that there should be 
any very large diversity in the average hygrometric condition 
of the whole ring at any two epochs. But in order to account 
for the observed results, both of these improbable hypotheses 
must be assumed. For, in the first place, if there were not an 
approach to uniformity throughout the ring on any given 
occasion, the variations due to the position of the moon in the 
shadow (as explained above) would be in a great measure masked, 
which, as a rule, they certainly are not; and, in the second 
place, if there were not a very large diversity in the average 
condition of the whole ring at two epochs, there would be no 
explanation of the phenomenon now under discussion. It 
cannot be that the large hygrometric differences which we know to 
exist between the tropical and the arctic regions should have an 
effect scarcely if at all appreciable, and that the small differences 
which are all that we can imagine possible between the average 
condition of the whole atmospheric ring at one time, and its 
average condition at another time, should suffice to explain the 
difference between conspicuous visibility at one time and absolute 
disappearance at another time. 
The suggestion of the solar corona as the source of the 
light which illuminates the eclipsed moon seems so obvious 
that I cannot suppose that it has not occurred to others besides 
myself. But, so far as I know, it has not hitherto been 
pubhshed, and certainly it has not been generally accepted. To 
my mind it fulfils all the conditions required. Whatever the 
