John Leslie (1766-1832) was a Scottish mathematician and physicist. He spent much of his career at the University of Edinburgh where he assumed the Chair of Mathematics previously occupied by John Playfair. Leslie wrote several textbooks, including *Elements of Geometry, Geometrical Analysis, and Plane Trigonometry* (1809). In his consideration and teaching of Euclidean geometry, he was a reformer moving away from the traditional approach to Euclid that had for so long been followed in England. The images viewed here are from the 1817 third edition of this work (note that “Geometrical Analysis” was removed from the title in the third and subsequent editions). The title page is signed by a previous owner of the book, Florian Cajori (1859-1930), whose last academic post was at the University of California, Berkeley, where he held a chair in the history of mathematics from 1918 onward.

In the "Preface," Leslie stated his objectives.

The introductory pages of the text initiate instruction by considering the overall definition of the subject of geometry.

Basic definitions and precepts are given:

A “Theorem-Proof” format is followed throughout the text.

Trigonometry follows the discussion on geometry and stands as a separate book.

*The images above are supplied through the courtesy of the University of California Libraries. The work may be viewed in its entirety in the* *Internet Archive**.*

Index to Mathematical Treasures