Thomas Drummond, a British naval officer and inventor, born in Edinburgh in October, 1797, died in Dublin, April 15, 1840. While a cadet at Woolwich he displayed unusual mathematical ability, and attracted considerable attention by rejecting as unsatisfactory a standard demonstration in conic sections, and supplying a new and original one, which was adopted in future text books. In 1820 he was employed in the trigonometrical survey of the United Kingdom. He had given considerable attention to chemistry, and conceived the idea that the incandescence of lime might be put to use for illuminating distant stations in the survey, as a substitute for the argand lamp. In 1824 he was transferred to the survey of Ireland, in which some improved method of illumination was still more a necessity, and there constructed his lamp. Its first trial was at Slieve Snaught, Donegal, and it was distinctly seen by the engineers at Devis mountain, 66 miles distant. Subsequently it was said to have been visible at a distance of 112 miles.

Drummond described his invention in the "Philosophical Transactions" for 1826. When quicklime is subjected to intense heat, such as is produced by the oxyhydrogen blowpipe, the light emitted is exceedingly powerful and dazzling; the lime itself is slowly volatilized, and the surface around is covered with its sublimate. Drummond placed the light thus produced in the focus of a parabolic mirror, which reflects the rays in parallel lines, thus directing the entire light toward a single point. Many experiments have been made to adapt the Drummond light to lighthouses; but the deficiency of divergence in the rays, and the difficulty of maintaining a regular supply of gases for the blowpipe, have thus far proved insurmountable. It has been applied to the gas microscope, in which it gives the prismatic colors almost as bright as in the solar spectrum. In 1825 Drummond invented a heliostat, which is still employed in the government survey of Great Britain. He made a large collection of scientific instruments, and carried on extensive experiments for their improvement; but the entire collection and the observatory that contained it were destroyed by a storm in a single night.

In 1835 he was appointed under secretary for Ireland. In 1836 he was placed at the head of a commission to plan a railway system for Ireland, and his scheme has been substantially followed. The oft quoted words, " Property has its duties as well as its rights," are from a letter which he wrote to the magistrates of Tipperary in 1838. He was a favorite with the Irish people, who erected a statue to his memory in the royal exchange of Dublin. A memoir of his professional life, by Capt. Lar-con, was published in 1841, in the 4th volume of "Papers on Subjects connected with the Duties of the Corps of Royal Engineers."