pleted early in 1868. A huge object-glass, twenty-five inches across and of the highest quality in form and finish, was ready to be placed in the tube. But its maker, worn out by the anxieties attendant on so vast an undertaking, died on 19 Oct. 1868. The great telescope was mounted in the following year. It is still the largest, and is believed to be the best refractor in the United Kingdom, though its qualities have been obscured by the murky air of Gateshead. Among the novelties introduced in its fittings was that of the illumination, by means of Geissler vacuum-tubes, both of micrometer-wires and circle-graduations. A seven-inch transit-instrument formed an adjunct to it.
Cooke has been called the ‘English Fraunhofer.’ He restored to this country some portion of its old supremacy in practical optics. He brought the system of equatorial mounting very near to its present perfection. The convenience of observers had never before been so carefully studied as by him, and observation owes to his inventive skill much of its present facility. By his application of steam to the grinding and polishing of lenses their production was rendered easy and cheap and their quality sure. His object-glasses were pronounced by the late Mr. Dawes (perhaps the highest authority then living) ‘extremely fine, both in definition and colour’ (Monthly Notices, xxv. 231). And the facility given by his method to their construction brought comparatively large instruments within the reach of an extensive class of amateur astronomers.
A pair of five-foot transits, constructed by Cooke for the Indian Trigonometrical Survey, were described by Lieutenant-colonel Strange before the Royal Society on 16 Feb. 1867 (Proc. R. Soc. xv. 385). They were among the largest portable instruments of their class, the telescopes possessing a clear aperture of five inches.
Cooke invented an automatic engine, of excellent performance, for the graduation of circles, and was the first to devise machinery for engraving figures upon them. He perfected the astronomical clock, and built nearly one hundred turret-clocks for public institutions and churches. Admirable workmanship was combined, in all his instruments, with elegance of form, while the thoroughness characteristic of his methods was exemplified in the practice adopted by him of cutting his own tools and casting his own metals. Simplicity, truthfulness, and modesty distinguished his private character. He was admitted a member of the Royal Astronomical Society in 1859, and contributed to its proceedings a paper, ‘On a new Driving-clock for Equatorials’ (Monthly Notices, xxviii. 210). He left two sons, well qualified to carry on his business.
[Monthly Notices, xxix. 130; Athenæum, 1868, ii. 534; Les Mondes, xviii. 331.]
COOKE, THOMAS POTTER (1786–1864), actor, was born on 23 April 1786, in Titchfield Street, Marylebone, where his father, whom he lost in his seventh year, practised as a surgeon. The sight of a nautical melodrama inspired Cooke with a passion, not for the stage, but for the sea. In 1796, accordingly, he sailed on board H.M.S. Raven to Toulon, in the siege of which port he took part. He was present (1797) at the battle off Cape St. Vincent, and was engaged in other actions. After narrowly escaping drowning off Cuxhaven, where the vessel on which he sailed was lost, and the crew had to take refuge in the rigging, he reached England, only to sail again on board the Prince of Wales, carrying Rear-admiral Sir Robert Calder, to the blockade of Brest. The peace of Amiens, 1802, deprived him of occupation. In January 1804 he made his début in an insignificant character at the Royalty Theatre in Wellclose Square. He was then engaged by Astley for the Amphitheatre, where he appeared as Nelson. He subsequently played at the Lyceum, and then joined the company of H. Johnston, who opened a theatre in Peter Street, Dublin. In 1809 he was engaged by Elliston as stage manager of the Surrey Theatre, at which house he remained a favourite. On 19 Oct. 1816 he appeared at Drury Lane as Diego Monez, an officer, in a melodrama attributed to Bell, and called ‘Watchword, or the Quito Gate.’ His name appears during the one or two following seasons to new characters, chiefly foreigners, such as Monsieur Pas in ‘Each for Himself,’ Almorad, a Moor, in ‘Manuel’ by Maturin, Hans Ketzler in Soane's ‘Castle Spectre,’ &c. On 9 Aug. 1820 Cooke made a great success at the Lyceum as Ruthven, the hero of the ‘ Vampire,’ and in the following year strengthened his reputation as Dirk Hatteraick in the ‘Witch of Derncleugh,’ a version of ‘Guy Mannering,’ George in the ‘Miller's Maid,’ and Frankenstein (1823) in ‘Presumption, or the Fate of Frankenstein.’ Cooke then joined the Covent Garden company, and played Zenocles in ‘Ali Pasha,’ by Howard Payne, on 19 Oct. 1822, Richard I in ‘Maid Marian’ on 3 Dec. 1822, and other parts. When, in 1825, Yates and Terry took the Adelphi, Cooke was engaged and played Long Tom Coffin in Fitzball's drama ‘The Pilot.’ At the close of the season he visited Paris, and presented ‘Le Monstre’ (Franken-
