Difference engine: Difference between revisions

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American [[George B. Grant]] started working on his calculating machine in 1869, unaware of the works of Babbage and Scheutz (Schentz). One year later (1870) he learned about difference engines and proceeded to design one himself, describing his construction in 1871. In 1874 the Boston Thursday Club raised a subscription for the construction of a large-scale model, which was built in 1876. It could be expanded to enhance precision and weighed about {{convert|2000|lb|kg}}.<ref name=":4" /><ref>{{Cite web|url=http://history-computer.com/Babbage/NextDifferentialEngines/Grant.html|title=History of Computers and Computing, Babbage, Next differential engines, George Grant|website=history-computer.com|access-date=2017-08-29}}</ref><ref>{{Cite book|url=https://archive.org/details/greatcentenniale00sandrich|title=The Great Centennial Exhibition Critically Described and Illustrated|last=Sandhurst|first=Phillip T.|date=1876|publisher=P. W. Ziegler & Company|pages=[https://archive.org/details/greatcentenniale00sandrich/page/423 423], 427}}</ref>

[[Christel Hamann]] built one machine (16-digit numbers and second-order differences) in 1909 for the "Tables of [[Julius Bauschinger|Bauschinger]] and Peters" ("Logarithmic-Trigonometrical Tables with eight decimal places"), which was first published in Leipzig in 1910. It weighed about {{convert|40|kg|lb}}.<ref>{{Cite web|url=https://web.archive.org/web/20120225033434/http://history-computer.com/Babbage/NextDifferentialEngines/Hamann.html| title=History of Computers and Computing, Babbage, Next differential engines, Hamann|website=history-computer.com|access-date=2017-09-14}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=vD7PAAAAMAAJ|title=Logarithmisch-trigonometrische Tafeln mit acht Dezimalstellen, enthaltend die Logarithmen aller Zahlen von 1 bis 200000 und die Logarithmen der trigonometrischen Funktionen f"ur jede Sexagesimalsekunde des Quadranten: Bd. Tafel der achtstelligen Logarithmen aller Zahlen von 1 bis 200000|last1=Bauschinger|first1=Julius|last2=Peters|first2=Jean|date=1958|publisher=H. R. Engelmann|pages=Preface V–VI}}</ref><ref>{{Cite book|url=https://archive.org/details/logarithmischtri01bausuoft|title=Logarithmisch-trigonometrische Tafeln, mit acht Dezimalstellen, enthaltend die Logarithmen aller Zahlen von 1 bis 200000 und die Logarithmen der trigonometrischen Funktionen für jede Sexagesimalsekunde des Quadranten. Neu berechnet und hrsg. von J. Bauschinger und J. Peters. Stereotypausg|last1=Bauschinger|first1=Julius|last2=Peters|first2=J. (Jean)|date=1910|publisher=Leipzig W. Englemann|others=Gerstein - University of Toronto|pages=Einleitung VI|language=de}}</ref>

[[Burroughs Corporation]] in about 1912 built a machine for the [[HM Nautical Almanac Office|Nautical Almanac Office]] which was used as a difference engine of second-order.<ref name=":5">{{Cite journal|last=Comrie|first=L. J.|date=1928-03-01|title=On the application of the BrunsvigaDupla calculating machine to double summation with finite differences|bibcode=1928MNRAS..88..447C|journal=Monthly Notices of the Royal Astronomical Society|volume=88|issue=5|pages=451, 453–454, 458–459|doi=10.1093/mnras/88.5.447|issn=0035-8711|via=[[Astrophysics Data System]]|doi-access=free}}</ref>{{Rp|451}}<ref>{{Cite book|url=https://archive.org/stream/moderninstrument00horsuoft#page/127/mode/1up/search/hudson|title=Modern instruments and methods of calculation : a handbook of the Napier Tercentenary Exhibition|last1=Horsburg|first1=E. M.|date=1914|___location=London|publisher=G. Bell|pages=127–131}}</ref> It was later replaced in 1929 by a Burroughs Class 11 (13-digit numbers and second-order differences, or 11-digit numbers and <nowiki>[at least up to]</nowiki> fifth-order differences).<ref>{{Cite journal|last=Comrie|first=L. J.|date=1932-04-01|title=The Nautical Almanac Office Burroughs machine|bibcode=1932MNRAS..92..523C|journal=Monthly Notices of the Royal Astronomical Society|volume=92|issue=6|pages=523–524, 537–538|doi=10.1093/mnras/92.6.523|issn=0035-8711|via=[[Astrophysics Data System]]|doi-access=free}}</ref>