Abstract :
Babbage´s expectations for his Difference Engine were those of a young enthusiast. Although he failed to complete his version of the engine, an independent implementation of his ideas was carried through by Georg and Edvard Scheutz. Two Scheutz engines were built and put to work, one at the Registrar-General´s Office in London and one at the Dudley Observatory in Albany, N. Y. They performed as intended, but failed to revolutionize the making of mathematical tables as Babbage had hoped they would. When Babbage was 45years old. he wrote, but did not publish, a description of the Analytical Engine. Here he showed vision verging on genius. His judgment on the design and utility of the Analytical Engine was as sound as his judgment on matters concerned with the Difference Engine was weak. Studies by A. G. Bromley, based on an examination of his notebooks, have brought out his remarkable achievements at what we would now call the microprogram level and also the insights that eluded him at the user level. His failure to publish may have been because he never arrived at what he regarded as a satisfactory system for programming at the user level.