The mathematician John Napier, 8th Laird of Merchistoun, educated at St. Andrews University and then in Europe, returned in 1571 to Scotland at the age of twenty-one and devoted himself to running his estate and taking part in the religious controversies of the time.
He employs some of his mathematical talents for theology, using the Book of Revelation to predict the Apocalypse, believing that the end of the world will occur in 1688 or 1700.
He is the inventor of logarithms as a computational tool, first propounding his methods in 1614, four years after the publication of his memorable discovery, in his principal work, Mirifici Logarithmorum Canonis Descriptio, containing thirty-seven pages of explanatory matter and ninety pages of tables, which will facilitate the advance of astronomy, dynamics, physics, and astrology.
The logarithm method supplants the more involved prosthaphaeresis, which relies on trigonometric identities, as a quick method of computing products.
Napier also publishes a small treatise on a simple way to perform multiplication, the Rabdologiae, introducing a calculating device which becomes known as Napier's Rods or Napier's Bones.
In an appendix, he explains another method of multiplication and division using metal plates, which is the direct antecedent of the slide rule, a mechanical means of calculation.
Another useful idea of his is Neper/Napier's circle (sometimes called Neper/Napier's pentagon), a mnemonic for spherical trigonometry.
Napier’s contemporaries describe a number of "secret inventions" including a round chariot that is an early version of a tank, giant mirrors that could burn the sails of enemy ships, a submarine, and an artillery piece that could apparently destroy a whole field of soldiers.
He is also believed to have developed one of the first iterations of the machine gun, testing it on a herd of sheep.
