Scottish mathematician John Napier (1550-1617) created a manually operated calculating device called Napier’s bones. A set of square rods carved from bone inscribed with numbers, it made multiplication, division, and finding square roots much easier. Napier based his device on an Arabic method introduced to Europe by the Italian mathematician Fibonacci (1175-1250).
German astronomer William Schickard built a calculating machine by remodelling Napier’s bones as cylinders. His clock could add and subtract six-digit numbers.