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
In my history of the slide rule[1], and my article on its invention[2] it is shewn that William Oughtred and not Edmund Wingate is the inventor, that Oughtred’s circular rule was described in print in 1632, his rectilinear rule in 1633. Richard Delamain is referred to as having tried to appropriate the invention to himself[3] and as having written a scurrilous pamphlet against Oughtred. All our information about Delamain was taken from De Morgan,[4] who, however, gives no evidence of having read any of Delamain’s writings on the slide rule. Through Dr. Arthur Hutchinson of Pembroke College, Cambridge, I learned that Delamain’s writings on the slide rule were available. In this article will be given: First, some details of the changes introduced during the seventeenth century in the design of Gunter’s scale by Edmund Wingate, Milbourn, Thomas Brown, John Brown and William Leybourn; second, an account of Delamain’s book of 1630 on the slide rule which antedates Oughtred’s first publication (though Oughtred’s date of invention is earlier than the date of Delamain’s alleged invention) and of Delamain’s later designs of slide rules; third, an account of the controversy between Delamain and Oughtred; fourth, an account of a later book on the slide rule written by William Oughtred, and of other seventeenth century books on the slide rule.