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Mathematical Treasure: Hieronymus Ditzel’s Geographiae

Author(s): 
Frank J. Swetz (The Pennsylvania State University)

Jerome [Hieronymus] Ditzel (1642–1710) was a German geographer, astronomer and mathematician. In his Geographiae, published posthumously in 1716, a section on requisite mathematics is included for the reader. The frontispiece shows the author revealing the  “hand-coded” secrets of his subject.

Frontispiece for Hieronymus Ditzel's 1716 Geographiae. Title page from Hieronymus Ditzel's 1716 Geographiae.

The material on mathematics begins with a consideration of squared numbers.

Page 12 from Hieronymus Ditzel's 1716 Geographiae. Page 13 from Hieronymus Ditzel's 1716 Geographiae.

The discussion of geometry opens with a consideration of the sphere.

Page 16 from Hieronymus Ditzel's 1716 Geographiae. Page 17 from Hieronymus Ditzel's 1716 Geographiae.

These images are presented courtesy of the John Carter Brown Library, Brown University. The full volume may be read here.

Index to Mathematical Treasures

Frank J. Swetz (The Pennsylvania State University), "Mathematical Treasure: Hieronymus Ditzel’s Geographiae," Convergence (September 2020)

Dummy View - NOT TO BE DELETED