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Page:Dictionary of National Biography volume 46.djvu/417

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Pritchard
Pritchard
405

Notices, xlvi. 2, 1. 512; Observatory, viii. 424, ix. 62), it has kept its place as an indispensable adjunct to photometric apparatus. By means of seventy thousand accurately observed extinctions with it he determined, in 1881–5, the relative magnitudes of 2,784 stars from the pole to ten degrees south of the equator, travelling to Cairo early in 1883 for the purpose of approximating more closely to the true value of atmospheric absorption. For the resulting valuable photometric catalogue, entitled ‘Uranometria Nova Oxoniensis,’ 1885, he received, jointly with Pickering, in February 1886, the Astronomical Society's gold medal (Monthly Notices, xlvi. 272).

Pritchard was a pioneer in the photographic measurement of stellar parallax. His trial-star was 61 Cygni, and from two hundred plates exposed in 1886 he derived a parallax of 0″.438. Encouraged by this promising result, he measured, between 1888 and 1892, twenty-eight stars, mostly of the second magnitude, obtaining, for stars of that grade of brightness, an average parallax of 0″.056, corresponding to a light-journey of fifty-eight years. The Royal Society signified their approval of this considerable performance by the bestowal, on 30 Nov. 1892, of a royal medal (Proc. Roy. Soc. lii. 312); yet Pritchard's data are undoubtedly affected by minute, insidious errors (Jacoby, Vierteljahrsschrift Astr. Gesellschaft, xxviii. 117).

Pritchard laid before the Royal Society, on 20 May 1886, a description of his elaborate ‘Researches in Stellar Photography: (1) in its Relation to the Photometry of the Stars; (2) its Applicability to Astronomical Measurements of great Precision’ (Proceedings, xl. 449). Some ‘Further Experience as regards the Magnitude of Stars obtained by Photography’ was imparted to the Royal Astronomical Society in 1891 (Monthly Notices, li. 430). He executed a series of light-measures of Nova Aurigæ in February and March 1892, both photographically and with the wedge-photometer (ib. lii. 366). His co-operation in the international scheme for charting the heavens was welcomed by the Paris congress of 1887; he received from Sir Howard Grubb one of the regulation instruments, and diligently experimented with it in 1890–1. The conclusions he thus arrived at were embodied in the ‘Compte Rendu’ of the conference in 1891 (p. 72). At the time of his death some progress had been made in photographing the zone assigned to Oxford. His ‘Report on the Capacities, in respect of Light and Photographic Action, of two Silver Glass Mirrors of different Focal Lengths’ (Proc. Roy. Soc. xli. 195) was founded on experiments undertaken at the request of the photographic committee of that body.

Elected F.R.S. on 6 Feb. 1840, Pritchard was a member of the council 1885–7. He was also a fellow of the Cambridge Philosophical Society and, from 1852, of the Geological Society. He proceeded M.A. by decree from New College, Oxford, on 11 March 1870, and D.D. in 1880; became, as Savilian professor, fellow of New College in 1883; and was, to his great delight, elected to an honorary fellowship of St. John's College, Cambridge, in 1886. He was placed on the Solar Physics Committee in 1885. He was full of plans for future work, and had, in especial, made all preparations for a photographic inquiry into the parallaxes of some of the Pleiades, when he died, after a very short illness, on 28 May 1893, in his eighty-sixth year, and was buried in Holywell cemetery, Oxford. He married, first, on 18 Dec. 1834, Emily, daughter of Mr. J. Newton; secondly, on 10 Aug. 1858, Rosalind, daughter of Mr. Alexander Campbell, who predeceased him by one year. He left children by both marriages.

Nothing could be more admirable than the ardour and originality with which Pritchard, at an advanced age, discharged the duties of his professorship. As many as fifteen students at a time were often receiving practical instruction in the subsidiary observatory fitted up for their use; Pritchard was greatly aided there by his assistants, Messrs, Plummer and Jenkin. Next to the stars, Pritchard loved flowers. He practised floriculture as a fine art, and had at Clapham one of the finest ferneries in England. Yet he would at all times have preferred parish work to his brilliant scientific avocations. ‘Providence,’ he used to say, ‘made me an astronomer, but gave me the heart of a divine.’

He published four numbers of ‘Astronomical Observations made at the University Observatory, Oxford,’ 1878–92. The first contained observations of Saturn's satellites, of four hundred double stars, and of several comets, with elements computed for these last, and for the three binaries, ξ Ursæ Majoris, 70 Ophiuchi, and μ2 Bootis. No. 2 was the ‘Uranometria Nova Oxoniensis,’ 1885; Nos. 3 and 4 were devoted to stellar photographic parallax. He communicated, during the last twenty years of his life, fifty astronomical papers to learned societies; wrote many excellent popular essays, including a series in ‘Good Words;’ and contributed several articles to the ninth edition of the ‘Encyclopædia Britannica,’ and to Smith's ‘Dictionary of the Bible,’ particularly that on the ‘Star of the Wise Men.’ His ‘Occa-