A Scottish mathematician, Napier studied at Saviour College in St. Andrews and traveled in Italy, France, and Germany. His inventions include a burning mirror for destroying ships, a mobile artillery piece, a metal assault vehicle, and an underwater navigation device. His reputation, however, rests chiefly on the invention of logarithms: these arithmetic functions were critical to the development of trigonometry. The invention was described in the posthumous work Mirifici logarithmorum canonis constructio (Edinburgh, 1619), edited by his son Robert. In Rabdologiae libri duo (Edinburgh, 1617), Napier described a computing system using what came to be known as "Napier's bones" - in essence, a mechanical multiplication table.