"The absolute wave-lengths of the H and K lines of calcium in some terrestrial sources."
1910 · Offprint from:
by ST. JOHN, Charles Edward (1857-1935).
Offprint from:: Astrophysical Journal, Vol. XXXI, 1910., 1910. Series: Contributions from the Mount Wilson Solar Observatory, No. 44. 253 x 172 mm. 8vo. 14 pp. 1 fig., 4 tables. Printed wrappers. Fine. FIRST SEPARATE EDITION. "St. John's research was mainly in solar physics. One of his earliest investigations (1910-1911) was of the H and K lines of ionized calcium in the solar spectrum. After measuring the absolute wave-lengths of these lines in terrestrial sources, he compared them with those of the corresponding emission and absorption lines observed in (truncated)