Editing Analytical engine (section)

== Influence ==
=== Predicted influence ===
Babbage understood that the existence of an automatic computer would kindle interest in the field now known as [[algorithmic efficiency]], writing in his ''Passages from the Life of a Philosopher'', "As soon as an analytical engine exists, it will necessarily guide the future course of the science. Whenever any result is sought by its aid, the question will then arise—By what course of calculation can these results be arrived at by the machine in the ''shortest time''?"{{sfn|Babbage|1864|p=137}}

=== Computer science ===
From 1872, Henry continued diligently with his father's work and then intermittently in retirement in 1875.<ref>{{cite web | title=The Babbage Engine – Key People – Henry Provost Babbage | publisher=Computer History Museum | url=http://www.computerhistory.org/babbage/henrybabbage/ | access-date=8 February 2011 | archive-url= https://web.archive.org/web/20110220215219/http://www.computerhistory.org/babbage/henrybabbage/| archive-date= 20 February 2011 }}</ref>

[[Percy Ludgate]] wrote about the engine in 1914<ref name=":0">{{Cite book|chapter-url=https://archive.org/stream/moderninstrument00horsuoft#page/127/mode/1up/search/1906|title=Modern instruments and methods of calculation : a handbook of the Napier Tercentenary Exhibition|last1=Horsburg|first1=E. M. (Ellice Martin)|last2=Napier Tercentenary Exhibition|date=1914|publisher=London : G. Bell|others=Gerstein – University of Toronto|pages=124–127|chapter=''Automatic Calculating Machines'' by P. E. Ludgate}}</ref> and published his own design for an analytical engine in 1909.<ref>{{cite journal |author=Ludgate, Percy E. |date=April 1909 |title=On a proposed analytical machine |journal=Scientific Proceedings of the Royal Dublin Society | volume=12 |issue=9 |pages=77–91 }}  Available on-line at:  [http://www.fano.co.uk/ludgate/paper.html Fano.co.UK] {{Webarchive|url=https://web.archive.org/web/20190807233247/http://www.fano.co.uk/ludgate/paper.html |date=7 August 2019 }}</ref><ref>{{Cite web |url=https://scss.tcd.ie/SCSSTreasuresCatalog/miscellany/TCD-SCSS-X.20121208.002/TCD-SCSS-X.20121208.002.pdf/ |title=The John Gabriel Byrne Computer Science Collection |access-date=8 August 2019 |archive-url=https://web.archive.org/web/20190416071721/https://www.scss.tcd.ie/SCSSTreasuresCatalog/miscellany/TCD-SCSS-X.20121208.002/TCD-SCSS-X.20121208.002.pdf |archive-date=16 April 2019 |url-status=dead }}</ref> It was drawn up in detail, but never built, and the drawings have never been found. Ludgate's engine would be much smaller (about {{Convert|230|L|cuft|lk=out|abbr=on}} than Babbage's, and hypothetically would be capable of multiplying two 20-decimal-digit numbers in about six seconds.{{Sfn|Randell|1982|p=4–5}}

In his work ''Essays on Automatics'' (1914) [[Leonardo Torres Quevedo]], inspired by Babbage, designed a theoretical electromechanical calculating machine which was to be controlled by a read-only program. The paper also contains the idea of [[floating-point arithmetic]].<ref>Torres Quevedo, Leonardo. [https://quickclick.es/rop/pdf/publico/1914/1914_tomoI_2043_01.pdf Automática: Complemento de la Teoría de las Máquinas, (pdf)], pp. 575–583, Revista de Obras Públicas, 19 November 1914.</ref><ref name="LTQ1915fr">Torres Quevedo. L. (1915). [http://diccan.com/dicoport/Torres.htm "Essais sur l'Automatique – Sa définition. Etendue théorique de ses applications"], ''Revue Génerale des Sciences Pures et Appliquées'', vol. 2, pp. 601–611.</ref><ref>Ronald T. Kneusel. ''[https://books.google.com/books?id=eq4ZDgAAQBAJ&dq=leonardo+torres+quevedo++electromechanical+machine+essays&pg=PA84 Numbers and Computers],'' Springer, pp. 84–85, 2017. {{ISBN|978-3319505084}}</ref> In 1920, to celebrate the 100th anniversary of the invention of the [[arithmometer]], Torres presented in Paris the electromechanical arithmometer, which consisted of an arithmetic unit connected to a (possibly remote) typewriter, on which commands could be typed and the results printed automatically.{{Sfn|Randell|1982|p=6, 11–13}}{{sfn|Bromley|1990}}

[[Vannevar Bush]]'s paper ''Instrumental Analysis'' (1936) included several references to Babbage's work. In the same year he started the Rapid Arithmetical Machine project to investigate the problems of constructing an electronic digital computer.<ref name=":2">{{Cite web |title=Percy Ludgate's Analytical Machine |url=http://www.fano.co.uk/ludgate/ |access-date=29 October 2018 |website=fano.co.uk |at=''From Analytical Engine to Electronic Digital Computer: The Contributions of Ludgate, Torres, and Bush'' by Brian Randell, 1982, Ludgate: pp. 4–5, Quevedo: pp. 6, 11–13, Bush: pp. 13, 16–17}}</ref>

Despite this groundwork, Babbage's work fell into historical obscurity, and the analytical engine was unknown to builders of electromechanical and electronic computing machines in the 1930s and 1940s when they began their work, resulting in the need to re-invent many of the architectural innovations Babbage had proposed. [[Howard Aiken]], who built the quickly-obsoleted electromechanical calculator, the [[Harvard Mark I]], between 1937 and 1945, praised Babbage's work likely as a way of enhancing his own stature, but knew nothing of the analytical engine's architecture during the construction of the Mark I, and considered his visit to the constructed portion of the analytical engine "the greatest disappointment of my life".{{sfn|Cohen|2000}} The Mark I showed no influence from the analytical engine and lacked the analytical engine's most prescient architectural feature, [[conditional branching]].{{sfn|Cohen|2000}} [[J. Presper Eckert]] and [[John W. Mauchly]] similarly were not aware of the details of Babbage's analytical engine work prior to the completion of their design for the first electronic general-purpose computer, the [[ENIAC]].<ref>{{cite web|url=https://special.lib.umn.edu/cbi/oh/pdf.phtml?id%3D245 |access-date=9 February 2011 |url-status=dead |archive-url=https://web.archive.org/web/20100724084105/http://special.lib.umn.edu/cbi/oh/pdf.phtml?id=245 |title=J. Presper Eckert Interview 28 October 1977|archive-date=24 July 2010 }}</ref><ref>{{cite web|url=http://invention.smithsonian.org/downloads/fa_cohc_tr_mauc730223.pdf |access-date=9 February 2011 |url-status=dead |archive-url=https://web.archive.org/web/20101111055745/http://invention.smithsonian.org//downloads/fa_cohc_tr_mauc730223.pdf |title=Computer Oral History Collection, 1969–1973, 1977 |archive-date=11 November 2010 }}</ref>