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HERSCHEL, SIR JOHN FREDERICK WILLIAM,...
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See also:HERSCHEL, See also:SIR See also: He experimented in See also:physical See also:optics; took up See also:astronomy in 1816; and in 1820, assisted by his father, he completed for a reflecting See also:telescope a See also:mirror of r8 in. See also:diameter and 20 ft. See also:focal length. This, subsequently improved by his own hands, became the See also:instrument which enabled him to effect the astronomical observations forming the See also:chief basis of his fame. In 1821–1823 we find him associated with Sir See also: Indeed, very shortly after taking his degree at Cambridge, he proposed himself as a See also:candidate for the vacant chair of chemistry in that university; but, as he said with some See also:humour, the result of the See also:election.was to leave him in a glorious minority of one. In fact Herschel had become an astronomer from a sense of See also:duty, and it was by filial See also:loyalty to his father's memory that he was now impelled to undertake the completion of the work nobly begun at Slough. William Herschel had searched the See also:northern heavens; John Herschel determined to explore the See also:southern, besides re-exploring northern skies. " I resolved," he said, " to attempt the completion of a survey of the whole See also:surface of the heavens; and for this purpose to transport into the other hemisphere the same instrument which had been employed in this, so as to give a unity to the results of both portions of the survey, and to render them comparable with each other." In accordance with this See also:resolution, he and his See also:family embarked for the Cape on the 13th See also:November 1833; they arrived in Table See also:Bay on the 15th January 1834; and proceedings, he says, " were pushed forward with such effect that on the 22nd of See also:February I was enabled to gratify my curiosity by a view of K Crucis, the nebula about n Argils, and some other remarkable See also:objects in the 20-ft. reflector, and on the See also:night of the 4th of March to commence a See also:regular course of sweeping." To give an adequate description of the vast See also:mass of labour completed during the next four busy years of his life at Feldhausen would require the transcription of a considerable portion of the Cape Observations, a See also:volume of unsurpassed See also:interest and importance; although it might perhaps be equalled by a judicious selection from Sir William's " Memoirs," now scattered through some See also:thirty volumes of the Philosophical Transactions. It was published, at the See also:sole expense of the See also:late See also:duke of See also:Northumberland, but not till 1847, nine years after the author's return to England, for the cogent See also:reason, that as he said, " The whole of the observations, as well as the entire work of reducing, arranging and preparing them for the See also:press, have been executed by myself." There are 164 pages of catalogues of southern nebulae and clusters of stars. There are then careful and elaborate drawings of the See also:great nebula in See also:Orion, and of the region surrounding the remarkable See also:star in Argo. The labour and the thought bestowed upon some of these objects are almost incredible; several months were spent upon a See also:minute spot in the heavens containing I216 stars, but which an See also:ordinary spangle, held at a distance of an See also:arm's length, would See also:eclipse. These catalogues and charts being completed, he proceeded to discuss their significance. He confirmed his father's See also:hypothesis that these wonderful masses of glowing vapours are not irregularly scattered over the visible heavens, but are collected in a sort of See also:canopy, whose vertex is at the See also:pole of that vast stratum of stars in which our See also:solar system finds itself buried, as Herschel supposed, at a See also:depth not greater than that of the See also:average distance from us of an See also:eleventh magnitude star. Then follows his See also:catalogue of the relative positions and magnitudes of the southern double stars, to one of which, y Virginis, he applied the beautiful method of orbital determination invented by himself, and he had the See also:satisfaction of witnessing the fulfilment ofhis prediction that the components would, in the course of their revolution, appear to See also:close up into a single star, inseparable by any telescopic See also:power. In the next See also:chapter he proceeded to describe his observations on the varying and relative brightness of the stars. It has been already detailed how his father began his scientific career by similar observations on stellar light-fluctuations, and how his remarks culminated years afterwards in the question whether the radiative changes of our See also:sun, due to the presence or See also:absence of sun-spots, affected our harvests and the See also:price of See also:corn. Sir John carried See also:speculation still farther, pointing out that See also:variations to the extent of See also:half a magnitude in the sun's brightness would See also:account for those See also:strange alternations of semi-See also:arctic and semi-tropical climates which See also:geological researches show to have occurred in various regions of our globe. Herschel returned to his English See also:home in the See also:spring of 1838. As was natural and right, he was welcomed with an enthusiastic greeting. By the See also:queen at her See also:coronation he was created a See also:baronet; and, what to him was better than all such rewards, other men caught the contagion of his example, and laboured in See also:fields similar to his own, with an adequate portion of his success. Herschel was a highly accomplished chemist. His discovery in 1819 of the solvent power of hyposulphite of soda on the otherwise insoluble salts of See also:silver was the prelude to its use as a fixing See also:agent in See also:photography; and he invented in 1834, independently of See also:Fox See also:Talbot, the See also:process of photography on sensitized See also:paper. He was the first See also:person to apply the now well-known terms See also:positive and negative to photographic images, and to imprint them upon See also:glass prepared by the See also:deposit of a sensitive film. He also paved the way for Sir See also:George See also:Stokes's discovery of See also:fluorescence, by his addition of the See also:lavender rays to the spectrum, and by his announcement in 1845 of " epipolic See also:dispersion," as exhibited by sulphate of See also:quinine. Several other important researches connected with the undulatory theory of light are embodied in his See also:treatise on " Light " published in the See also:Encyclopaedia metropolitana. Perhaps no See also:man can become a truly great mathematician or philosopher if devoid of imaginative power. Joht Herschel possessed this endowment to a large extent; and • he solaced his declining years with the See also:translation of the Iliad into See also:verse, having earlier executed a similar version of See also:Schiller's Walk. But the See also:main work of his later life was the collection of all his father's catalogues of nebulae and double stars combined with his own observations and those of other astronomers each into a single volume. He lived to See also:complete the former, to present it to the Royal Society, and to see it published in a See also:separate form in the Philosophical Transactions, vol. cliv). The latter work he See also:left unfinished, bequeathing it, in its imperfect form, to the Astronomical Society. That society printed a portion of it, which serves as an See also:index to the observations of various astronomers on double stars up to the year 1866. A complete See also:list of his contributions to learned See also:societies will be found in the Royal Society's great catalogue, and from them may be gathered most of the records of his busy scientific life. Sir John Herschel met with an amount of public recognition which was unusual in the time of his illustrious father. Naturally he was a member of almost every important learned society in both hemispheres. For five years he held the same office of See also:master of the See also:mint, which more than a See also:century before had belonged to Sir See also:Isaac See also:Newton; his friends also offered to propose him as See also:president of the Royal Society and again as member of See also:parliament for the university of Cambridge, but neither position was desired by him. In private life Sir John Herschel was a See also:firm and most active friend; he had no jealousies; he avoided all scientific feuds; he gladly See also:lent a helping See also:hand to those who consulted him in scientific difficulties;"'he never discouraged, and still less disparaged, men younger than or inferior to himself; he was pleased by appreciation of his work without being solicitous for See also:applause; it was said of him by a discriminating critic, and without extravagance, that " his was a life full of serenity of the See also:sage and the docile innocence of a See also:child." He died at See also:Collingwood, his See also:residence near See also:Hawkhurst in See also:Kent, on the 11th of May 1871, in the seventy-ninth year of his age, and his remains are interred in See also:Westminster See also:Abbey close to the See also:grave of Sir Isaac Newton. Besides the laborious Cape Observations, Sir John Herschel was the author of several books, one of which at least, On the Study of Natural See also:Philosophy (183o), possesses an interest which no future advances of the subjects on which he wrote can obliterate. In 1849 came the Outlines of Astronomy, a volume still replete with See also:charm and instruction; His articles, " See also:Meteorology," ' Physical See also:Geography," and " Telescope," contributed to the 8th edition of the Encyclopaedia Britannica, were afterwards published separately. When he was at the Cape he was more than once assisted in the attempts there made to diffuse a love of knowledge among men not engaged in See also:literary pursuits; and with the same purpose he, on his return to England, published, in See also:Good Words and elsewhere, a See also:series of papers on interesting points of natural philosophy, subsequently collected in a volume called See also:Familiar Lectures on Scientific Subjects. Another less widely known volume is his Collected Addresses, in which he is seen in his happiest and most instructive See also:mood. See also Mrs John Herschel, " Memoir of See also:Caroline Herschel," See also:Month. Notices See also:Roy. Astr. Society, xxxii. I22 (C. See also:Pritchard) ; Proceedings Roy. Society, xx. p. xvii. (T. See also:Romney See also:Robinson) ; Proceedings Roy. Society of See also:Edinburgh vii. 543 (P. G. See also:Tait); Nature iv. 69; E. Dunkin, Obituary Notices, p. 47; See also:Report Brit. Association (1871), p. lxxxv. (See also:Lord See also:Kelvin); The Times. (May 13, 1871); R. See also: Clerke, The Herschels and See also:Modern Astronomy; J. H. Madler, Geschichte der Himmelskunde, Bd. ii.; Memoires de la Societe Physique de Geneve, xxi. 586 (E. See also:Gautier). Reductions, based on See also:standard magnitudes of 919 southern stars, observed by Herschel in sequences of relative brightness, were published by W. Doberck in the Astrophysical See also:Journal, xi. 192, 270, and in Harvard See also:Annals, vol. xli., No. viii. (C. P.; A. M. Additional information and CommentsThere are no comments yet for this article.
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