Mathematical Treasures - Leonard Digges' Tectonicon

This is the title page of the Tectonicon by Leonard Digges (1520-1559), a 1634 edition of the work originally published in 1556. Digges was an English astronomer, mathematician, and instrument maker, credited with the invention of the reflecting telescope and the theodolite. His book discusses methods of measurement.

At the beginning of the book, Digges discusses basic ideas of arithmetic, preliminary to dealing with measurement.

On page 4, basic ideas of measurement are discussed.

And on page 5, we have definitions of various parts of the circle. See also images from Stratioticos, by Leonard Digges, and from Pantometria, by Leonard Digges and his son, Thomas Digges.

Index to Mathematical Treasures​