UNIVERSITY OF CALIFORNIA PUBLICATIONS IN MATHEMATICS Vol. 1, No. 9, pp. 187-209 February 17, 1920 ON THE HISTORY OF GUNTER’S SCALE AND THE SLIDE RULE DURING THE SEVENTEENTH CENTURY BY FLORIAN CAJORI UNIVERSITY OF CALIFORNIA PRESS BERKELEY TABLE OF CONTENTS PAGE I. Introduction 187 II. Innovations in Gunter’s Scale 188 Changes introduced by Edmund Wingate 188 Changes introduced by Milbourn 189 Changes introduced by Thomas Brown and John Brown 190 Changes introduced by William Leybourn 192 III. Richard Delamain’s “Grammelogia” 192 Different editions or impressions 194 Description of Delamain’s instrument of 1630 195 Delamain’s later designs, and directions for using his instruments 197 IV. Controversy between Oughtred and Delamain on the invention of the circular slide rule 199 V. Independence and priority of invention 203 VI. Oughtred’s “Gauging Line,” 1633 206 VII. Other seventeenth century slide rules 207 I. INTRODUCTION