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.