John Napier lived from 1550 to 4 April 1617. He was the son of Sir Archibald Napier of Merchiston Castle in Edinburgh, and Janet Bothwell, herself a daughter of a member of Parliament. He went on to to become a hugely influential mathematician who invented logarithms, who produced a calculating machine called Napier's Rods or Napier's Bones, and who did much to further the interests of the decimal point in mathematics. Today one of Edinburgh's universities, Napier University, is named after him and is built around his family home of Merchiston Castle. The wider picture in Scotland at the time is set out in our Historical Timeline.
Napier had little formal schooling, instead being tutored at home before being sent to the University of St Andrews at the age of 13. He then travelled to Europe to continue his studies. In 1571 he returned to Edinburgh aged 21 and the following year married Elizabeth Stirling, daughter of the Scottish mathematician James Stirling. They had two children together before Elizabeth died in 1579. Napier later married Agnes Chisholm, and they had ten children. In 1608 Napier inherited the family estates and moved with his wife and children to Merchiston Castle.
It was his writing on a non mathematical subject that first brought Napier to public notice. In 1593 he published a book criticising Catholicism, entitled A Plaine Discovery of the Whole Revelation of St John. In 16th Century terms (and in post Reformation Scotland) the book proved to be a best seller and was translated into a number of other languages.
But it was the 37 pages of text and 90 pages of tables in his Mirifici Logarithmorum Canonis Descriptio which revolutionised the day to day work of contemporaries involved in a wide range of scientific pursuits that was to be his lasting legacy. For it was Napier who developed logarithms. He had an interest in astronomy, but found the computations extremely time consuming. So instead he focused on a means of making the computations easier. He succeeded, and anyone who was at school before the universal use of electronic calculators, will remember well thumbed books of log tables. He also invented Napiers Rods or Bones, a portable means of making multiplication more easy.
More widely, Napier proved to be something of a Scottish Galileo. He came up with many ways of improving the fertility of his farming estates, and he was known to have produced drawings for a round chariot that can be viewed as an early version of the tank; giant mirrors which could set fire to the sails of enemy ships; and an early submarine. He was also believed by some to have magical powers, and in 1594 he was employed to search for hidden treasure at Fast Castle.
He wasn't infallible, however. Napier applied his mathematical expertise to the Book of Revelation in the Bible and predicted that the end of the world would come in either 1688 or 1700. His own death in 1617 prevented him discovering the error in his calculations.