Mathematical Treasure: Philippe Danfrie’s Declaration de l'usage du Graphometre

Philippe Danfrie (1532–1606) was a Parisian instrument maker. One of his inventions to be used in land surveying was a graphometer. In 1597, he published Declaration de l'usage du Graphometre to explain and promote the use of his instrument. The book also demonstrated another of his interests, printing and engraving, as it was typeset with a unique cursive font.

One of his explanatory diagrams:

Danfrie explained how to survey a fortified town from a distance, using a measured baseline. He pointed out that this goal can be accomplished from as far away as the eye can manage and thus out of danger from cannon-fire.

A digitization of the copy owned by the George Peabody Library of Johns Hopkins University is available in the Internet Archive.

Reference

Vervliet, Hendrik D. L. 2020, March. Danfrie Reconsidered. Philippe Danfrié's (d. 1606) Civilite Types. The Library 21(1): 3–45. https://doi.org/10.1093/library/21.1.3.

Index to Mathematical Treasures