Page 646 - 89 history of astronomy_opt

Huggins and Father Secchi,[24] of Rome.
The former began by devoting years of work
principally to the most accurate study of
a few stars. The latter devoted the years
from 1863 to 1867 to a general survey of
the whole heavens, including 4,000 stars.
He divided these into four principal classes,
which have been of the greatest service. Half
of his stars belonged to the first class, in-
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