Account of the Changes that have happened, during the last Twenty-five Years, in the relative Situation of Double-stars; with an Investigation of the Cause to which they are owing. Read June 9, 1803. (+) Continuation of an Account ofthe Changes that have happened in the relative Situation of double stars. Read June 7, 1804. (2 Papers).

(London, Bulwer and Co., 1803 a. 1804). 4to. Without wrappers as extracted from "Philosophical Transactions of the Royal Society of London." Year 1803-Part II. Pp. 339-382 and 2 engraved plates. a. Year 1804-Part II. Pp. 353-384 a. 1 engraved plate. Light browning to a few margins. 2 plates with scattered brownspots, otherwise clean and wide-margined.

First appearance of these fundamental paper in cosmology and physics as they contains the FIRST OBSERVATIONAL DATA TO SUPPORT THAT NEWTON'S DYNAMICAL LAWS HOLDS OUTSIDE THE SOLAR SYSTEM. Herschel shows here that the circulating motions of double-stars were under gravitational forces. Until then the validity of the law of gravity was only established within the solar system. Now, a century after the establishment of the law, it was traced out in the motion of incredibly distant stars and the theory first truly earned its title of Universal. The exact proof of the mutual gravitation of the double-stars was only obtained five years after Herschel's death, when the motions of the stars were more precisely dtermined.

One of the most notable of Herschel's discoveries of double-stars, binary stars. A first cataloque of such pairs was published early in 1782 and contained 269, of which 227 were new discoveries. "Twenty years after the publication of his first cataloque Herschel was of Michell's opinion - Michell had expressed the opinion that the odds in favour of a physical relation between the members of Herschel's newly discovered double stars were "beyond arithmetic" - but was able to support it by evidence of an entirely novel and much more direct character. A series of observations of Castor, presented in two papers in the "Philosophical Transaction" in 1803 and 1804 (the paperS offered ), which were fortunately supplemented by an observation of Bradley's in 1759, had shewn a progressive alteration in the direction of the line joining its two components, of such a character as to leave no doubt that the two stars were revolving round one another; and there were five oher cases in which a similar motion was observed...it was shown that the double-star was really formed by a connected pair of stars near enough to influence one another's mortion."(Berry in "A Short History of Astronomy" pp. 342-43).

Order-nr.: 45133

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