This volume is intended to bring together, as much as possible, the information scattered in various places, regarding the Calculating Machines of Charles Babbage, and to make it available for those interested in the subject, who may wish to pursue it further.

He has never himself written a full description of any of his machines. He preferred, while his energies lasted, to devote them to the actual progress and development of the design. As regards the Analytical Engine, he considered the sketch at the commencement of this volume by the Count Menabrea, and the translation of it with notes by Lady Lovelace, as entirely disposing of the mathematical aspect; proving “that the whole of the developments and operations of Analysis are now capable of being executed by machinery.”

In the “Passages from the Life of a Philosopher,” published in 1864, and written with the object of interesting the public in these machines, he mentions on the last page a forthcoming “History of the Analytical Engine.” As materials towards it he had an Article from the “Philosophical Magazine” of September 1853, and Article XXIX. from Vol. III. of the “Scientific Memoirs,” containing the translation and notes by Lady Lovelace above mentioned, reprinted; and added several chapters of “The Passages” and other papers. He also supplied a complete list of the drawings, notations and note books of the Analytical Engine. Thus the first 294 pages of this book were printed in his lifetime; but owing to the weariness and infirmities of age, he did nothing more, and the historical and descriptive part was never written.