A Geometric Surprise in Dürer's Engraving of St. Jerome in His Study

An extended abstract of the present paper was print-published as "Abstract of: A Geometric Surprise in Dürer's Engraving of St. Jerome in His Study" in Leonardo Volume 51, Issue 5, October 2018.  That abstract has a DOI, https://doi.org/10.1162/leon_a_01543 .

The complete paper was concurrently posted by Leonardo/MIT Press as "supplementary material" to the abstract, but without its own DOI.  The present paper is identical to that one except for having different permissions for figures 11a and 11b.