Chandler, Seth Carlo

(b. Boston, Massachusetts, 17 September 1846; d. Wellesley Hills, Massachusetts, 31 December 1913),

astronomy.

Chandler was educated at the English High School in Boston. After graduation (1861) he became private assistant to Benjamin Apthorp Gould and involved with the U.S. Coast Survey, which he joined in 1864. Rather than accompany Gould to Argentina, Chandler worked for many years as an actuary and did not resume his scientific activities until 1881.

He then became associated with the Harvard College observatory, evolving with J. Ritchie the Science Observer Code (1881), a system for transmitting by telegraph information about newly discovered comets. Chandler published many papers on comets and variable stars and compiled several useful catalogs of the latter objects.

His most important contribution to science was the discovery of the variation of latitude. Soon after arriving at Harvard, Chandler devised the almucantar, an instrument by means of which one relates positions of stars not to the meridian but to a small circle centered at the zenith. In his discussion (1891) of observations made with this instrument during 1884–1885 he concluded that the latitude varied with amplitude 0″.3 in a period of fourteen months. Observations made about the same time in Berlin by Kü st-ner had shown a similar variation. From an exhaustive rediscussion of observations made as far back as Bradley’s time, Chandler was able to verify the fourteen-month period and to show that there was in addition a variation having a period of twelve months. His announcements met with considerable opposition, initially because Euler had shown that any variation would have a period of ten months; but as Newcomb pointed out, since the earth is not completely rigid, the period would be longer.

Chandler was editor of the Astronomical Journal from 1896 to 1909 and subsequently an associate editor. He received an LL. D. degree from DePauw University (1891), the Watson Medal of the National Academy of Sciences (1895), and the Gold Medal of the Royal Astronomical Society (1896).

BIBLIOGRAPHY

Chandler’s “On the Variation of Latitude” is in Astronomical Journal11 (1891), 59–61, 65–70. 75–79, 83– 86;12 (1892), 17–22,57–62, 65–72,97–101; 13 (1893). 159– 162. Chandler’s many papers in the Astronomical Journal are listed in the General Index to the Journal, 1–50 (1948), 15–17.

Chandler is discussed in H, H. Turner. Astronomical Discovery (London, 1904), pp. 177–217. See also Turner’s obituary notice of Chandler in Monthly Notices of the Royal Astronomical Society, 75 (1915), 251–256.

Brian G. Marsden