William OughtredDied 30 Jun 1660 at age 85 (born 5 Mar 1575).English mathematician and Episcopal minister who invented the earliest form of the slide rule, two identical linear or circular logarithmic scales held together and adjusted by hand. Improvements involving the familiar inner rule with tongue-in-groove linear construction came later. He introduced the familiar multiplication sign x in a 1631 textbook, along with the first use of the abbreviations sin, cos and tan.[DSB gives date of birth as 5 Mar 1575. EB gives 5 Mar 1574.] |