WILLIAM OUGHTRED WILLIAM OUGHTRED A GREAT SEVENTEENTH-CENTURY TEACHER OF MATHEMATICS BY FLORIAN CAJORI, Ph.D. Professor of Mathematics Colorado College CHICAGO LONDON THE OPEN COURT PUBLISHING COMPANY 1916 Copyright 1916 By The Open Court Publishing Co. All Rights Reserved Published September 1916 Composed and Printed By The University of Chicago Press Chicago, Illinois, U.S.A. TABLE OF CONTENTS PAGE Introduction 1 CHAPTER I. Oughtred’s Life 3 At School and University 3 As Rector and Amateur Mathematician 6 His Wife 7 In Danger of Sequestration 8 His Teaching 9 Appearance and Habits 12 Alleged Travel Abroad 14 His Death 15 II. Principal Works 17 Clavis mathematicae 17 Circles of Proportion and Trigonometrie 35 Solution of Numerical Equations 39 Logarithms 46 Invention of the Slide Rule; Controversy on Priority of Invention 46 III. Minor Works 50 IV. Oughtred’s Influence upon Mathematical Progress and Teaching 57 Oughtred and Harriot 57 Oughtred’s Pupils 58 Oughtred, the “Todhunter of the Seventeenth Century” 60 Was Descartes Indebted to Oughtred? 69 The Spread of Oughtred’s Notations 73 V. Oughtred’s Ideas on the Teaching of Mathematics 84 General Statement 84 Mathematics, “a Science of the Eye” 85