A replica of John Napier's bones from 1618. These prismatic pieces were used to multiply, divide and even compute square and cubic roots.
John Napier, a young and relatively wealthy Scottish scientist, invented in 1617/18 a system which is considered as the first mechanical calculator. Prismatic wooden pieces hold numbers which correspond to a multiplication table. To multiply, several bones are laid out one against the other. The sum obtained by adding the numbers in a horizontal row give one digit of the result. The replica was made by Francis Massen for the Computarium.