Jet ION TEOIRILAUL 
GroLoaists heartily participate in the satisfaction which 
astronomers justly feel over the great mass of accurate data 
which favorable conditions and their own zeal and skill enabled 
them to gather from the recent solar eclipse. Geologists offer 
their cordial felicitations not only as fellow scientists rejoicing in 
the common advancement of science for its own sake, and for its 
influence on the world, but because they are themselves con- 
cerned in the solution of the solar problems. Especially are 
they interested in those questions of the sun’s constitution and 
internal activities which bear upon his sources of heat, present, 
past, and future; for these vitally touch the limitations of geologic 
history. It is impossible, therefore, for historical geologists to 
be indifferent to the results of any investigation that promises 
to throw light upon the thermal endurance of the sun. 
The central subject of interest in the recent observations, 
the constitution of the corona, may seem quite remote from any 
geologic relationship, but, as in so many other cases in the his- 
tory of science, light upon dark problems may come from an 
unexpected source. It is not beyond the limits of speculation 
to conceive that the corona may prove to be the very phenom- 
enon that will point the way to a revised estimate of the thermal 
possibilities of the sun and thus to a revised measure of its past 
duration and of the age of the earth as one of its dependencies. 
Some hint of the possibilities may be found in the logical 
sequences of one of the alternative working hypotheses relative 
to the coronal nature. If the conception that it is formed of 
extremely attenuated matter driven away at great velocities, after 
the analogy of the tails of comets, should be substantiated, it will 
necessarily be followed by the problem of the origin of such 
attenuated matter. In the case of comets such supposed matter 
may be assumed to be simply an accessory constituent brought 
in from distant space and deveioped by approach to the sun — 
and soon exhausted in the case of captured comets—but such a 
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