In 1830 he took his printer, Richard Bentley (1794-1871) [q. v.], into a partnership, which was, however, dissolved in August 1832. Having first set up business again at Windsor for a short time, Colburn paid a forfeiture for breaking the covenant not to commence publishing within twenty miles of London, and opened a house in Great Marlborough Street. He finally retired from business in favour of Messrs. Hurst & Blackett, but kept his name attached to a few books. These were Warburton's ' Crescent and the Cross,' the ' Diaries ' of Evelyn and Pepys, Miss Strickland's ' Lives,' Burke's ' Peerage,' &c., the copyrights of which produced at Messrs. Southgate's, on 26 May 1857, about 14,000l. (Notes and Queries, 2nd ser. iii. 458). Colburn amassed a considerable fortune, his property being sworn as under 35,000l. He was twice married, the second time to Eliza Anne, only daughter of Captain Crosbie, who survived him. He died at his house in Bryanston 'Square on 16 Aug. 1855.
[Gent. Mag. November 1855; Curwen's History of Booksellers (1873), pp. 279-95; A. A. Watts, Alaric Watts, a narrative, 1884; P. J. Murray's Life of John Banim, 1857; Timperley's Encyclopaedia, 1839, p. 931.]
COLBY, THOMAS FREDERICK, LL.D. (1784–1852), major-general, and director of the ordnance survey, belonged to a family of property in South Wales. He was the eldest child of Major Thomas Colby, royal marines (d. 1813), by his wife, Cornelia Hadden, sister of Major-general Hadden, royal artillery, sometime surveyor-general of the ordnance. He was born at St. Margaret's-next-Rochester on 1 Sept. 1784. His boyhood was passed in charge of his father's sisters at the family place, Rhosygilwen, near Newcastle Emlyn, South Wales, and at school at Northfleet, Kent, under the Rev. W. Crakelt, M.A., translator of Manduit's 'Spherical Trigonometry,' and adapter of various educational works. Thence he was transferred to the Royal Military Academy, Woolwich, and passed out for the royal engineers before attaining the age of seventeen. His commissions were as follows: second lieutenant royal engineers, 2 July 1801; first lieutenant, 6 Aug. 1802; captain (second), 1 July 1807; brevet major, 19 July 1821; regimental lieutenant-colonel, 29 July 1825; regimental colonel, 10 Jan. 1837; major-general, 9 Nov. 1846.
At the beginning of the present century the system of triangulation carried on in 1784 and 1787 by General Roy, under the auspices of the Royal Society, for the geodetic connection of Greenwich and Paris observatories, and resumed after Roy's death by the board of ordnance for a survey of South Britain, had extended over the southern counties into Devonshire and Cornwall. It was becoming the custom to attach young engineer officers to the survey for a time to learn topographical drawing under the ordnance draughtsmen. Either in this way or through the good offices of his uncle, Colonel Hadden, royal artillery, at that time secretary to the master-general, young Colby attracted the notice of Major Mudge, director of the ordnance survey, who asked that he should be attached in some permanent manner to that duty. The request was granted the same day, 12 Jan. 1802, on which date commenced the future General Colby's connection with the ordnance survey, which ultimately extended over a period of forty-five years. Up to that date the British ordnance survey had helped little towards the solution of the great astronomical problem of the earth's figure, but the tardy completion of a new zenith-sector, a noble instrument, ordered by the board of ordnance from the famous maker, Ramsden, years before, induced Major Mudge to apply the projected extension northwards of the ordnance triangulation to the measurement of an arc of the meridian between Dunnose, Isle of Wight, and a station near the mouth of the Tees, and the young lieutenant's first services appear to have been in connection with the sector observations made at Dunnose in the summer of 1802. In December 1803, when on duty at Liskeard, Colby met with a fearful accident through the bursting of a pistol loaded with small shot with which he was practising, his left hand being so shattered as to necessitate amputation at the wrist, and part of the barrel or charge being permanently lodged in the skull, so as to seriously affect his health through life, and eventually to cause his death. Youth, a vigorous constitution, and the kind care of friends carried him through this trial, and he recovered sufficiently to resume his survey duties, and in the face of lifelong difficulties, which would have daunted any ordinary man, he persevered in his profession. In 1804 he was observing the pole star for azimuths at Beaumaris; in 1806 he was assisting Colonel Mudge in the measurement of a base-line on Rhuddlan Marsh, near St. Asaph, and in astronomical observations in Delamere Forest, Cheshire, and on the Yorkshire moors; later, again, he was selecting trigonometrical stations on the mountains in South Wales. The intervals were spent in the ordnance map office, in the Tower of London, in computing results and superintending the construction and engraving of the ordnance
