English: Drawing of the 'Stepped Reckoner', a mechanical calculator invented by German mathematician Gottfried Wilhelm Leibniz in 1674 and completed in 1694. About 67 cm (23 inches) long. In the upper view the top plate is removed to show the works. This was the first calculating machine able to do all four arithmetic operations: addition, subtraction, multiplication, and division.
The machine consists of two parts, the 12 digit accumulator section (pars immobilis) in back and the 8 digit input section in front. The input section can be moved using the crank (K) and worm gear to align different digits of the two sections. The 8 dials (rotae minusculae) on the input section are used to set the operand number into the machine. The telephone-like dial (rota majuscula) is used to set the multiplier. Turning the crank (magna rota) on the front performs the calculation. The result appears in the 12 windows in the accumulator section.
Ця робота перебуває у суспільному надбанні у країнах і територіях, де авторське право охороняється протягом життя автора та 70 років після того або менше.
{{Information |Description=Drawing of the ''Staffelwalze'' (English: 'Stepped Reckoner'), a mechanical calculator invented by German mathematician Gottfried von Leibniz in 1674 and complet