Leonard Digges was a well-known English

English people

The English are a nation and ethnic group native to England, who speak English. The English identity is of early mediaeval origin, when they were known in Old English as the Anglecynn. England is now a country of the United Kingdom, and the majority of English people in England are British Citizens...

 mathematician

Mathematician

A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

 and surveyor

Surveying

See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

, credited with the invention of the theodolite

Theodolite

A theodolite is a precision instrument for measuring angles in the horizontal and vertical planes. Theodolites are mainly used for surveying applications, and have been adapted for specialized purposes in fields like metrology and rocket launch technology...

, and a great popularizer of science through his writings in English on surveying, cartography, and military engineering. Much of his work was expanded on, annotated, and published by his son, Thomas Digges

Thomas Digges

Sir Thomas Digges was an English mathematician and astronomer. He was the first to expound the Copernican system in English but discarded the notion of a fixed shell of immoveable stars to postulate infinitely many stars at varying distances; he was also first to postulate the "dark night sky...

. His son followed in his footsteps and was a pivotal player in the popularization of Copernicus's book De revolutionibus orbium coelestium

De revolutionibus orbium coelestium

De revolutionibus orbium coelestium is the seminal work on the heliocentric theory of the Renaissance astronomer Nicolaus Copernicus...

. 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 to view distant objects and people.