To the works already mentioned the following must be added:—A volume published by Simon Finet, without the author's knowledge, containing Orationes duos in Tolosam, epistolarum libri duo, carminum libri duo, and epistolarum amicorum liber, 1533; De re navali liber, 1537; Genethliacum Claudii Doleti, 1539 (a collection of Latin poems on the birth of his son, translated into French as VAvant-Naissance de Claude Dolet, 1539) ; La maniere de bien traduire d une languc en une autre, and De la ponctuation franqaisc, 1541; Le Manuel du Chevalier Chretien and Lc vrai moyen de se bien confesses, both translated from Erasmus's Latin, 1542; Bref Discours de la Rcpublique franqaise, "" f ii fiernm/J. Knf#r 1544, a poem giving an account of his escape from prison, which was reprinted in 1836 by Techener. See Nee de la Rochelle, Vie d Estienne Dolet, Paris, 1799; Joseph Boulmier, " Estienne Dolet," in the Revue de Paris, 1855, and a separate work, Estienne Dolet, sa vie, &c., Paris, 1857; A. F. Didot, Essai sur la Typograpliie. The proces or trial of Dolet was published in 1836, by A. H. Taillandier from the registers of the parlement of Paris.
DOLGELLY, a market and assize town of Merionethshire, North Wales, situated at the junction of the Aran with the Wnion, and at the northern base of Cader Idris, 19 miles S.W. of Bala and 9 miles E. of Barmouth, with both of which it is connected by railway. The town consists of a series of small squares and narrow streets, the houses being built of stone. It contains a market hall, assize hall, county gaol, and parish church. An old building, described as the Parliament House, is said to have been the place in which Owen Glendower assembled his parliament in 1404. Dolgelly, which is the principal town of Merionethshire, forms a local board district. There is an inconsiderable manufacture of coarse flannels and tweeds carried on by the inhabitants. Population in 1871, 2357.
DOLLOND, John (1706–1761), the celebrated optician, was the son of a French refugee, a silk-weaver at Spitalfields, where he was born, June 10, 1706. He was early trained to his father's occupation, but made leisure for the acquisition of a knowledge of mathematics, physics, Greek, Latin, the elements of anatomy, and other subjects. In 1752 he abandoned silk-weaving in order to join his son Peter, who had entered upon business as an optical instrument-maker in Vine Court, and before long he became universally celebrated as an optician. His last and most important contribution to the Philosophical Transactions, for which he, in 1758, received the Copley medal of the Royal Society, gave a description of the various experiments, begun early in 1757, on the combined effect of water and prisms and lenses of glass, by which he was led to the discovery of a means of constructing achromatic lenses. Sir Isaac Newton had stated in his Optics “that all refracting substances diverged the prismatic colours in a constant proportion to their mean refraction,” and consequently “that refraction could not be produced without colour,” for which reason “no improvement could be expected in the refracting telescope.” Dollond, however, found that as flint glass causes a greater dispersion in proportion to its refractive power than crown glass, achromatic magnified images could be obtained by using a combination of a doubly concave lens of the former substance with a doubly convex lens of the latter. As the two glasses to be combined were the segments of spheres of considerable curvature, the aberrations from their surfaces were very great, but by varying the surfaces he was enabled to make the aberrations equal, so that, as the refractions of the two glasses were contrary, they corrected each other. In 1761 Dollond was appointed optician to the king, and became a fellow of the Royal Society on September 30th of that year, whilst reading a work by Clairaut on the theory of the moon, he had an attack of apoplexy, of which he died in a few hours.
Dollond's published papers are “A letter to Mr James Short, F.R.S., concerning an Improvement of Reflecting Telescopes;” a second letter to Mr Short “Concerning a Mistake in M Euler's Theorem for Correcting the Aberration in the Object-Glasses of Refracting Telescopes;” and “A Description of a Contrivance for measuring Small Angles”—Phil. Trans. 1753, pp. 103, 287, 178; “An Explanation of an Instrument for measuring Small Angles,” ibid. 1754, p. 551; and “An Account of some Experiments concerning the different Refrangibility of Light,” ibid., 1758, p. 733. See Kelly, Life of John Dollond, 3d ed. 1808.
was born at Dolornieu, near Tour-du-Pin, in the department of Isere in France, June 24, 1750. He was admitted in his infancy a member of the Order of Malta. When in his 19th year he quarrelled with a knight of the galley on which he was serving, and in the duel that ensued killed him. In consonance with the statutes of his order, Dolomieu was condemned to death for his crime, but in consideration of his youth the grand master granted him a pardon, which, at the instance of Cardinal Torrigiani, was confirmed by Pope Clement XIII., and after nine months imprisonment he was set at liberty. Throughout that period he had solaced himself with the study of the physi cal sciences, and during his subsequent residence at Metz he continued to devote himself to them. In 1775 he pub lished his Recherclies sur la pesanteur des corps a di/erentes distances du centre de la tcrre, and two Italian translations of mineralogical treatises by Cronstedt and Bergmann. These works gained for him the honour of election as a corresponding member of the Academy of Sciences at Paris. To obtain leisure to follow his favourite pursuits Dolomieu now threw up the commission which, since the age of fifteen, he had held in the carabineers, and in 1777 he accompanied the bailli De Rohan to Portugal. In the following year he visited Spain, and in 1780 and 1781 Sicily and the adjacent islands. Two months of the year 1782 were spent in examining the geological structure of the Pyrenees, and in 1783 the earthquake of Calabria induced him to go to Italy. The scientific results of these excursions are given in his Voyage aux Ues de Lipari ; Memoire sur le tremblement de terre de la Calabre ; Memoire sur les Ues Ponces, et catalogue raisonne des produits de I Etna, and other works. In 1789 and 1790 he busied himself with an examination of the Alps, his observations on which form the subject of numerous memoirs published in the Journal de Physique. The mineral dolomite, which was named after him, was first described by Dolomieu in 1791. He returned to France in that year, bringing with him rich collections of minerals. On September 14, 1792, the Due de la Rochefoucault, with whom he had been for twenty years on terms of the closest intimacy, was assassinated at Forges, and Dolomieu retired with the widow and daughter of the duke to their estate of Roche Guyon, where he wrote several important scientific papers. The events of the 9th Thermidor (July 27, 1794) having restored the country to some tranquillity, Dolomieu recom menced his geological tours, and visited various parts of France with which he had been previously unacquainted. He was in 1796 appointed engineer and professor at the school of mines, and was chosen a member of the Institute at the time of its formation. At the end of 1797 he joined the scientific staff which in 1798 accompanied Bonaparte s expedition to Egypt. He had proceeded up the Nile as far as Cairo when ill health made his return to Europe
necessary, and on March 7, 17 V J7, he set sail from