Author(s):

Frank J. Swetz (The Pennsylvania State University)

Two of the primary texts to teach mathematics in Great Britain during the nineteenth century were John Playfair’s *Elements of Geometry* (1795) and James Wood’s *The Elements of Algebra,* also first published in 1795. While these books were popular and their authors well respected, several mathematics masters wrote supplements and additions to these works. One such work was the *Supplement to Playfair’s Geometry and Wood’s Algebra, Completing a Course of Mathematics in Theory and Practice*, composed by Thomas Duncan (1777-1858) and published in Edinburgh in 1822 and in London in 1824. Duncan was a respected teacher of mathematics in Scotland; he served as Rector of the Dundee Academy from 1801 until 1820, when he was appointed the Regius Professor of Mathematics at the University of St Andrews.

In his discussion on pages 118-119, Duncan attempted an intuitive approach to the concept of a mathematical limit.

*This material is obtained through the courtesy of the Peabody Library of Johns Hopkins University.*

Index to Mathematical Treasures

Frank J. Swetz (The Pennsylvania State University), "Mathematical Treasure: Duncan Clarifies Playfair & Wood," *Convergence* (June 2018)