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EDWARD CHARLES PICKERING (1846- )

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Originally appearing in Volume V21, Page 583 of the 1911 Encyclopedia Britannica.
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EDWARD See also:CHARLES See also:PICKERING (1846- )  , See also:American physicist and astronomer, was See also:born in See also:Boston on the 19th of See also:July 1846 . He graduated in 1865 at the See also:Lawrence Scientific School of Harvard, where for the next two years he was a teacher of See also:mathematics . Subsequently he became See also:professor of physics at the See also:Massachusetts See also:Institute of Technology, and in 1876 he was appointed professor of See also:astronomy and director of the Harvard See also:College See also:observatory . In 1877 he decided to devote one of the telescopes of the observatory to stellar See also:photometry, and after an exhaustive trial of various forms of photo-meters, he devised the See also:meridian photometer (see PHOTOMETRY, STELLAR), which seemed to be See also:free from most of the See also:sources of See also:error . With the first See also:instrument of this See also:kind, having objectives of 1.5 See also:inch See also:aperture, he measured the brightness of 4260 stars, including all stars down to the 6th magnitude between the See also:North See also:Pole and -30° See also:declination . With the See also:object of reaching fainter stars, Professor See also:Pickering constructed another instrument of larger dimensions, and with this more than a million observations have been made . The first important See also:work undertaken with it was a revision of the magnitudes given in the See also:Bonn Durchmusterung . On the completion of this, Professor Pickering decided to undertake the survey of the See also:southern hemisphere . An expedition, under the direction of Prof . S . I . See also:Bailey, was accordingly despatched (1889), and the meridian photometer erected successively in three different positions on the slopes of the See also:Andes .

The third of these was See also:

Arequipa, at which a permanent See also:branch of the Harvard Observatory is now located . The .magnitudes of nearly 8000 southern stars were determined, including 1428 stars of the 6th magnitude and brighter . The instrument was then returned to See also:Cambridge (U.S.A.), where the survey extended so as to include all stars of magnitude 7.5 down to -40° declination, after which it was once more sent back to Arequipa . In 1886 the widow of See also:Henry See also:Draper, one of the pioneers of stellar See also:spectroscopy, made a liberal See also:provision for carrying on spectroscopic investigations at Harvard College in memory of her See also:husband . With Professor Pickering's usual comprehensiveness, the inquiry was so arranged as to See also:cover the whole See also:sky; and with four telescopes—two at Cambridge for the See also:northern hemisphere, and two at Arequipa in See also:Peru for the southern—to which a See also:fine 24-in. photographic See also:telescope was afterwards added, no fewer than 75,000 photographs had been obtained up to the beginning of 1901 . These investigations have yielded many important discoveries, not only of new stars, and of large See also:numbers of variable stars, but also of a wholly new class of See also:double stars whose binary See also:character is only revealed by peculiarities in their spectra . The important conclusion has been already derived that the See also:majority of the stars in the Milky Way belong to one See also:special type .

End of Article: EDWARD CHARLES PICKERING (1846- )
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