Thomas Drummond lived from 10 October 1797 to 15 April 1840. He was an engineer and inventor of the Drummond Light who worked for the Ordnance Survey of Ireland before becoming a senior administrator in Ireland. The wider picture in Scotland at the time is set out in our Historical Timeline. Thomas Drummond was the second of three sons of James Drummond and his wife Elizabeth Somers. He was born in Edinburgh and attended Edinburgh High School. In 1810 at the age of 13 he became a student at the University of Edinburgh, and three years later he became a cadet at the military academy at Woolwich. He gained a commission in the Royal Engineers in 1815 where he gained a reputation as a skilled surveyor. In the early 1820s he worked on a survey of the Highlands, while passing the winter months in London. In 1824 Drummond took up a post with the Ordnance Survey of Ireland, at the time engaged on the first comprehensive survey of Ireland. This process was assisted by an invention which still bears Drummond's name. The Drummond Light used the newly discovered principle of limelight, caused by an oxyhydrogen flame heating a cylinder of quicklime, to project a bright light great distances. It was shown that the Drummond Light could be seen at a distance of 68 miles, allowing surveyors to triangulate more easily and with greater accuracy. In the early 1830s Drummond worked for the government in London, and in 1835 he married the heiress Maria Kinnaird. They went on to have three daughters together. Soon afterwards he returned to Ireland as Irish Under-Secretary, the senior civil servant in the administration in Dublin. He was said to have been a fair administrator and was rated highly by the Irish. Drummond was still in post in Dublin when he died in 1840 at the age of just 42, reportedly as a result of overwork.