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Nature volume 92, pages 459460 (18 December 1913) | Download Citation



A REFRACTION ACTING RADIALLY FROM THE SUN.—In the expression for the variation of latitude, a term exists which is independent of the position of the observing station and which has a periodic character. M. L. Courvoisier has suggested that either the sun has an atmosphere which extends to very great distances or that the aether is denser nearer the sun, causing a small refraction in the light of stars, and thus producing this periodic variation in their positions. M. L. Courvoisier's paper, entitled “Ueber systematische Abweichungen der Sternpositionen im Sinne einer jährlichen Refraction” (K. Sternwarte, Berlin, No. 15), indicated that many series of observations pointed towards the existence of this refraction varying in amount with the angular separation, according to a formula which he deduced. His observation included a number of stars at different distances, both in right ascension and declination from the sun. The amount of this refraction near the sun he derived from observations of Venus near upper culmination between the years 1858 and 1909. Mr. F. E. Ross points out a correction to Courvoisier's yearly refraction in Astronomische Nachrichten, No. 4699, due to the observations of Venus being compared with an ephemeris computed from Leverrier's tables, which, as he says, are in error in a respect important in a discussion of this kind. The result of the correction is greatly to increase the refraction in the neighbourhood of the sun found by Courvoisier.

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