Babbage's calculating engines
The principal source of information for the technical operation of Babbage's Difference and Analytical engines, and an extremely difficult book to obtain. Toward the end of his life, Babbage began assembling his own and other's previously published writings on the Difference and Analytical Engines with the intent of publishing a history of the machines, but died before he could accomplish this task. He had the first 294 pages of this work typeset and printed on slightly varying types of paper during his lifetime. It would appear that its purpose was to collect the most significant published writings, many of which had appeared as obscure pamphlets or in little-read journals, together with a listing of what remained unpublished, including all of Babbage's notebooks and engineering drawings (listed on pp. 271-294), in the hope that his unfinished projects might be completed at some future date. The book was completed by Babbage's youngest son, Major-General Henry Prevost Babbage, to whom Babbage had bequeathed his calculating engines and everything pertaining to them. Were it not for this volume and the bibliography of Babbage's works published both here (on the last three printed pages of the book) and in Babbage's autobiography, Babbage's achievements might have been forgotten. As it turned out the information was never implemented literally, probably because construction of the mechanical Analytical Engine was just too complex a project for any organization except a government to undertake. Yet Babbage's ambitions and his ideas remained alive in the minds of people working in mechanical computation long after his technology had fallen into obsolescence. When Vannevar Bush suggested in 1936 that electromechanical technology might be the way to realize "Babbage's large conception" of the Analytical Engine, he cited this volume among his references; and in building the electromechanical Harvard Mark I, Howard Aiken saw himself as fulfilling Babbage's ambition.