William OUGHTRED (1574-1660)

William Oughtred built in 1627 the first slide rule . This instrument is actually a “circle of calculation” where scales are plotted on concentric circumferences. Oughtred calls it “circles of proportion”.
Shortly thereafter, Wingate developed the straight-line rule which was then manufactured by many "artists". For more than a century and a half, they were practically only used in Great Britain. The first slide rules were mainly used to calculate the volume of barrels and taxes on alcohol in harbours, or to measure trees.