John Napier (1550-1617), Scottish mathematician. Napier, from a wealthy family, was educated in France and at St Andrews in Scotland. He studied mathematics as a hobby and published his first logarithm tables in 1614, also developing decimal notation. For the log tables he chose the transendental number e (approximately 2.717) as the base. These Napierian, or natural, logarithms are most relevant to exponential systems. His logarithms were a key mathematical advance that greatly helped Kepler in his calculations of planetary motion. This 1870 engraving by Samuel Freeman is based on a 1616 painting held at the University of Edinburgh.