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There is nothing mysterious, as some have tried to maintain, about the applicability of mathematics. What we get by abstraction from something can be returned.
Introduction to the Foundations of Mathematics.
Thomas Digges' Pantometria
This is the title page of A Geometrical Practise Named Pantometria, a guide to applied geometry published by Thomas Digges (1546-1595) in 1571. Pantometria was completed by Thomas from a manuscript left by his father, Leonard Digges, who died when Thomas was 13 years old. After his father's death, Thomas became the ward of John Dee (1527-1609), sometime scientific advisor to Queen Elizabeth I. Thomas was greatly influenced by Dee, and remained friends with him throughout his life. Thomas Digges became a recognized astronomer and the leader of the English Copernicans.
This diagram shows how to measure the height of a tower using a quadrant.
This diagram shows how to use a plane table to take sightings on a fortified city during a siege. Both Leonard and Thomas Digges, father and son, wrote about military applications of mathematics.