Huyghens and Boerhaave. He was the inventor of a machine called the planetarium, which served to determine the exact distances of the heavenly bodies according to the systems of Newton and Copernicus. He also erected a ventilator, by order, in a room over the House of Commons. Desaguliers contributed a vast number of papers on light, colours, the barometer, &c., to the ‘Philosophical Transactions,’ a list of which is to be found in Maty's index to the ‘Philosophical Transactions.’ James Cawthorn, in his poem ‘The Vanity of Human Enjoyments,’ credits Desaguliers with poverty at death. A portrait is in Nichols's ‘Anecdotes,’ ix. 640–1. He left three sons, of whom John Theophilus (1718–1752) was vicar of Cratfield and Lexfield, Suffolk. Thomas, the youngest, is separately noticed.
He published also: 1. ‘Treatise of Fortifications,’ trans. from French, Oxford, 1711, 8vo. 2. ‘Fires Improved; being a new Method of Building Chimneys, so as to prevent their Smoaking,’ London, 1716, 8vo; the author broke with the publisher Curll because of his shameless puffs. 3. ‘Physics: Mechanical Lectures,’ London, 1717, 8vo. 4. A translation of ‘The Motion of Water and other Fluids,’ London, 1718, 8vo. 5. A translation of Gravesande's ‘Mathematical Elements of Natural Philosophy,’ London, 1721, 4to. Other editions 1726, 1736, and 1747. 6. ‘The Constitutions of the Free-Masons; containing the History of that Fraternity,’ London, 1732, 4to. Desaguliers and J. Anderson were the joint compilers of this publication, which forms a part of Kenny's Masonic Archæological Library. 7. ‘A Course of Mechanical and Experimental Philosophy,’ written in French and English [London, 1724], 8vo; a second edition in 1725. 8. ‘An Experimental Course of Astronomy’ [a syllabus only], 1725, 8vo. 9. ‘The Newtonian System, an allegorical poem,’ London, 1728, 4to. 10. A translation of the second edition of Gregory's ‘Elements of Catoptrics and Dioptrics,’ with an account, in the appendix, of reflecting telescopes, London, 1734–5, 8vo. 11. ‘A Course of Experimental Philosophy,’ London, 1734, 2 vols. 4to, of which a second edition was published in 1745, and a third in 1763. ‘A System of Experimental Philosophy proved by Mechanics,’ London, 1719, 4to, published in Desaguliers's name by Paul Dawson, was disavowed by him. 12. ‘Examen des trois dissertations publiées sur la figure de la terre,’ Oldenburg, 1738, 12mo; second edition in 1741, 8vo. 13. ‘Dissertation on Electricity,’ London, 1742, 8vo, a disquisition for which he was awarded the prize of the academy of Bordeaux for the best essay on electricity. A French version of the work was published the same year at Bordeaux. 14. ‘An Account of the Mechanism of an Automaton playing on the German Flute,’ translated from the French, London, 1742, 4to. In theology he seems to have left only a thanksgiving sermon preached at Hampton Court in 1716 before George I.
[Smiles's Huguenots in England and Ireland, pp. 245–6, Lond. 1880; Maty's Index to the Phil. Trans. pp. 607–10; Cooke's Preacher's Assistant, i. 245; House and Farm Accounts of Gawthorpe Hall, Chetham Soc. xli. 276–9; Biog, Brit.; Lettres Familières du Baron de Bielfeld, i. 283–6, The Hague, 1763.]
DESAGULIERS, THOMAS (1725?–1780), lieutenant-general and colonel commandant of the royal artillery, was the grandson of Jean des Aguliers, protestant pastor of Aitré, near La Rochelle, and after the revocation of the edict of Nantes minister of the French chapel in Swallow Street, and youngest son of Dr. John Theophilus Desaguliers [q. v.] He entered the regiment of royal artillery as a cadet on 1 Jan. 1740, and was promoted second lieutenant on 1 Sept. 1741, first lieutenant on 1 Feb. 1742, captain-lieutenant on 3 April 1743, and captain on 1 Jan. 1745. He first saw service in Flanders in 1744, when he joined the royal artillery train under Colonel Belford, and remained on the continent until the close of the war of the Austrian succession in 1748, being present at the battle of Fontenoy, as well as many minor engagements. On his return to England, Captain Desaguliers was made chief firemaster at Woolwich on 1 April 1748, a post which he held for thirty-two years, until his death in 1780. The chief firemaster was the superintendent of Woolwich arsenal, and Desaguliers was the first scientific maker of cannon and the first regular investigator into the powers of gunnery in the English army. He was promoted lieutenant-colonel on 5 Feb. 1757, and in 1761 was summoned from his experiments and manufactures to take command of the siege train and the force of artillerymen intended to accompany the expedition to the island of Belleisle, off the west coast of France. This was the first opportunity for testing on a large scale the improvements made in siege artillery since the days of Marlborough, and Desaguliers was able to put his ideas into practice. General Studholme Hodgson was in command, with Gene-
