Mathematical Treasure: Dodgson’s Trigonometric Symbols

In 1861, mathematician Charles Dodgson (pen name Lewis Carroll) published a pamphlet for the undergraduates at Oxford University. Entitled The Formulae of Plane Trigonometry, a unique feature of its contents was a new system of symbols for use in abbreviating the names of the basic trigonometric functions: sine, cosine, .... The symbols devised by Carroll reflected the geometric origins of the functions they represented. The British literary magazine Athenaeum published a review of the pamphlet in which the symbols were shown and criticized. The clipping below of the review from the Athenaeum comes from Lewis Carroll’s personal scrapbook. Dodgson's symbols were not adopted for popular use. Can you determine the geometric associations indicated by each symbol?

This image is obtained through the courtesy of the Digital Public Library of America.

Index to Mathematical Treasures