Leonard Digges (c.1515 – c.1559) was a well-known English mathematician and surveyor, credited with the invention of the theodolite, and a great populariser of science through his writings in English on surveying, cartography, and military engineering. His birth date is variously suggested as c.1515 or c.1520 (but certainly by 1530). Much of his work was expanded on, annotated, and published by his son, Thomas Digges. His son followed in his footsteps and was a pivotal player in the popularisation of Copernicus's book De revolutionibus orbium coelestium. Notes written by Thomas Digges in the publication of the book Pantometria in 1570 contain descriptions of how Leonard Digges made use of a "proportional Glass" to view distant objects and people. Some, such as astronomer and historian Colin Ronan, claim this describes a reflecting or refracting telescope built between 1540 and 1559, but its vague description and claimed performance makes it dubious. Biography Leonard Digges, born about 1515, was the only son of James Digges (born c.1473), esquire, of Digges Court and Broome in Barham, Kent, by his second wife, Philippe Engham, the daughter of John Engham, esquire, of Chart, Kent. James Digges had been High Sheriff of Kent in 1510–11, and had married as his first wife Mildred Fineux, the daughter of Sir John Fineux, Chief Justice of the King's Bench, and Elizabeth Apuldrefield, by whom he had an only son, John Digges, who married Mildred Scott, the daughter of Sir John Scott (d. 7 October 1533) of Scot's Hall in Smeeth, Kent. John Digges predeceased his father, leaving two sons by his wife, Mildred Scott, William Digges and Francis Digges. James Digges made his last will on 20 February 1535/6 requesting burial in the north chancel of the church of Barham, 'where my mother and my wife do lie', and naming as executors his second wife, Philippe; John Sackville, esquire; his nephew, Robert Brent, gentleman; and his son, Leonard, with Sir William Hawte as overseer. The will was proved on 24 November 1540, at which time his second wife, Philippe, was still living. Leonard Digges was the grandson of John Digges, esquire, of Digges Court and Broome, High Sheriff of Kent in 1495-6, and his wife Joan Clifton, the daughter and co-heiress of Sir Gervase Clifton of Clifton, Nottinghamshire, London, and Brabourne, Kent, by his first wife, Isabel Herbert, daughter of Vincent Herbert, esquire. Leonard Digges' aunt, Isabel Digges, the daughter