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Mathematical Treasure: Two Works of Joseph Fenn

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

In 1772, Joseph Fenn published The Complete Accountant: Being a System of Arithmetic, Both Theoretical and Practical. The text was employed at his school in Dublin.

Title page of The Complete Accountant by Joseph Fenn, 1772

The first page of the text begins with a discussion of computations, numbers and units:

First page of The Complete Accountant by Joseph Fenn, 1772

A plate from the text illustrating solids:

Page of solid geometry diagrams from The Complete Accountant by Joseph Fenn, 1772

In 1769, Fenn published an English version of Euclid’s Elements. Below is Proposition 31 from Book 6, which generalizes the Pythagorean Theorem (Proposition 47 of Book 1) from area of squares to areas of any similar plane figures.

Propostion 31 from Book 6 of Euclid's Elements, edited by Joseph Fenn, 1769

The historian of mathematics Florian Cajori noted that Fenn's work contains a statement similar to Playfair’s Axiom.  Consider the footnote on page 44 shown below:

Page 44 of Euclid's Elements, edited by Joseph Fenn, 1769

The first four images were obtained from the Joseph L. Rousseau Collection of Mathematics and Ciphering books, Millersville University Library, and the fifth image from the HathiTrust Digital Library.

Index to Mathematical Treasures

Frank J. Swetz (The Pennsylvania State University), "Mathematical Treasure: Two Works of Joseph Fenn," Convergence (March 2019)

Dummy View - NOT TO BE DELETED