One of the books Pamela Smith referred to: Leonard Digges, A booke named Tectonicon, […]. Leonard Digges. London, F. Kyngston, 1605. Online on: https://openlibrary.org/books/OL23282093M/A_booke_named_Tectonicon_brieflie_shewing_the_exact_measuring_and_speedie_reckoning_all_manner_of_la.