Thomas Colby (1784-1852) was an officer in the Royal Engineers and a Director of the Ordnance Survey. He was responsible for much of the initial mapping of Scotland and Ireland. Some of his books came into the possession of Aberystwyth University after 1912 following a gift by another member of his family. Many of the volumes are concerned with mathematics and surveying but there are also some interesting ex-dono items from other important figures of the day, including Charles Babbage, Thomas Young and Robert Stevenson. In later years Colby also collected some interesting antiquarian volumes including a Pliny from 1563.