Page 471 - 89 history of astronomy_opt

carrying out the observation is not quite so
simple as what is here described.
By choosing another line of the spec-
trum instead of calcium K–for example, the
hydrogen line Hˆaˆaˆa–we obtain two photographs,
one showing the appearance of the calcium
floculi, and the other of the hydrogen flo-
culi, on the same part of the solar surface;
and nothing is more astonishing than to
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