Dollond, George (DNB00)
DOLLAND, GEORGE (1774–1852), optician, was born in London on 25 Jan. 1774. In early life he bore his father's name of Huggins, but changed it by royal patent to Dollond on entering into partnership with his maternal uncle, Peter Dollond [q. v.], who took charge of his education on his father's premature death. From Mr. George Lloyd's seminary at Kennington he was sent early in 1787 to learn the trade of mathematical instrument-making in Mr. Fairbone's manufactory, and in March 1788 commenced his apprenticeship to his uncle. A severe illness in 1792 kept him long between life and death; but he recovered, served out his time, and showed such diligence and ability that he was placed in exclusive charge of the mathematical department of the establishment in St. Paul's Churchyard. He was admitted to partnership in November 1805, and after his uncle's retirement in 1819 conducted the business alone until his death at his residence in Camberwell on 13 May 1852, at the age of seventy-eight. He was a thoroughly skilled mechanician and optician, and the numerous instruments constructed by him for use in astronomy, geodesy, and navigation were models of workmanship. The public observatories of Cambridge, Madras, and Travancore were equipped by him; he mounted for Mr. Dawes in 1830 the five-foot equatorial employed in his earlier observations of double stars (Mem. R. A. Soc. viii. 61); and built similar but larger instruments for Admiral Smyth, Lord Wrottesley, and Mr. Bishop.
Dollond's ‘Account of a Micrometer made of Rock Crystal’ was laid before the Royal Society on 25 Jan. 1821 (Phil. Trans. cxi. 101). This improvement upon the Abbé Rochon's double-refracting micrometer consisted in employing for the eye lens a sphere of rock crystal, the rotation of which on an axis perpendicular to that of the telescope and to the plane of double refraction gave the means of measuring small angles by the separation of the resulting two images. Dawes found such instruments, owing to the exquisite definition given to them by Dollond, a useful adjunct to the wire micrometer in the measurement of close double stars (Mem. R. A. Soc. xxxv. 144; Gill, Encycl. Brit. xvi. 252). Dollond also independently invented in 1819, and was the first to construct, a micrometer similar to the ‘dioptric’ one described by Ramsden in 1779, in which the principle of the divided lens was adapted to the eye-piece. Dr. Pearson procured one from him for twelve guineas, but found it too heavy for use with an ordinary achromatic (Pearson, Practical Astronomy, ii. 184).
On 13 April 1821 Dollond communicated to the Astronomical Society a ‘Description of a Repeating Instrument upon a new construction’ (Mem. R. A. Soc. i. 55), a kind of altazimuth in which the repeating principle was applied to both vertical and horizontal circles; and on 14 Nov. 1823, ‘A Short Account of a new Instrument for Measuring Vertical and Horizontal Angles’ (ib. ii. 125), otherwise called a ‘double altitude instrument,’ with which altitudes could be taken by direct and reflected vision simultaneously, thus dispensing with level or plumb line. His ‘Account of a Concave Achromatic Glass Lens as adapted to the Wired Micrometer when applied to a Telescope, which has the Power of increasing the Magnifying Power of the Telescope without increasing the Diameter of the Micrometer Wires,’ was read before the Royal Society on 27 Feb. 1834 (Phil. Trans. cxxiv. 199). It described a skilful application of Barlow's concave lens to the micrometer, specially designed to meet Dawes's needs in double-star measurement, and highly approved by him. Dollond's last invention was an ‘atmospheric recorder,’ for which he received the council medal of the Great Exhibition of 1851. By its means, varying atmospheric pressure, temperature, force and direction of wind, rainfall, evaporation, and electrical phenomena registered themselves simultaneously during periods limited only by the length of paper on the roller.
Dollond took an active part in the foundation of the Astronomical Society in 1820, and attended diligently at the council meetings until near the close of his life. He was elected a member of the Royal Society on 23 Dec. 1819, and was one of the original fellows of the Royal Geographical Society. He observed the partial solar eclipse of 7 Sept. 1820 at Greenwich (Mem. R. A. Soc. i. 138). In his business relations he set an example of probity and punctuality; he was highly esteemed in private life, and enjoyed the friendship of the leading scientific men of his time.[Monthly Notices, xiii. 110; Journ. Geog. Soc. 1853, p. lxxiii; R. Soc. Cat. of Scientific Papers; a Catalogue of the Instruments sold by Dollond in 1829 is contained in Astr. Nach. viii. 42.]