The spiral of obscuration
By: by Frederick H. Seares ...
Series: Contributions from the Mount Wilson Solar Observatory.; no. 139
Published: 1917
Place of publication: [Chicago
Language: eng
Subjects: Stars -- Distribution.
Notes: Cover-title.
At head of title: Carnegie Institution of Washington.
"Reprinted from the Astrophysical Journal, vol. XLVI, 1917."