11. He tried to establish a business of manufacturing and selling calculating machines , with unclear success. 12. Calculating machines did not become commercially viable until 1851, when 9's complement method for subtractions.13. So, he invented a " calculating machine " designed to ease the monotony of clerical work. 14. He developed a rotating camera and calculating machines . 15. He took great interest in mechanical calculating machines . 16. Helmut Schreyer ) and Kurt Pannke ( a calculating machines manufacturer in Berlin ) to do so. 17. He also constructed an early calculating machine . 18. Wiener used the term in reference to " calculus ratiocinator ", a calculating machine constructed by Leibniz. 19. Among them, ones of antique slide rules, early calculating machines , and maps that chart the evolution of cartography. 20. The name comptometer was formerly in wide use as a generic name for this class of calculating machine .
