Editing Charles Babbage (section)

===Difference engine===
{{main|Difference engine}}
[[File:Babbage Difference Engine.jpg|thumb|The Science Museum's Difference Engine No. 2, built from Babbage's design]]
[[File:Babbage difference engine drawing.gif|thumb|Portion of Babbage's difference engine]]

Babbage began in 1822 with what he called the difference engine, made to compute values of [[polynomial function]]s. It was created to calculate a series of values automatically. By using the method of finite differences, it was possible to avoid the need for multiplication and division.<ref>{{Cite web|url=https://www.britannica.com/technology/Difference-Engine|title=Difference Engine {{!}} calculating machine|website=Encyclopædia Britannica|access-date=13 May 2019}}</ref>

For a prototype difference engine, Babbage brought in [[Joseph Clement]] to implement the design, in 1823. Clement worked to high standards, but his [[machine tool]]s were particularly elaborate. Under the standard terms of business of the time, he could charge for their construction, and would also own them. He and Babbage fell out over costs around 1831.<ref>{{cite ODNB|id=37291|title=Clement, Joseph|first=Anita|last=McConnell}}</ref>

Some parts of the prototype survive in the [[Museum of the History of Science, Oxford]].<ref>{{Cite journal | first = Denis | last = Roegel | title = Prototype Fragments from Babbage's First Difference Engine | journal=IEEE Annals of the History of Computing | volume = 31 | pages = 70–75 | date = April–June 2009 | issue = 2 | doi = 10.1109/MAHC.2009.31 | s2cid = 45564453 }}</ref> This prototype evolved into the "first difference engine". It remained unfinished and the finished portion is located at the Science Museum in London. This first difference engine would have been composed of around 25,000 parts, weighed {{Convert|15|short ton|kg|spell=in|lk=in|sigfig=3}}, and would have been {{Convert|8|ft|m|1|abbr=on}} tall. Although Babbage received ample funding for the project, it was never completed. He later (1847–1849) produced detailed drawings for an improved version,"Difference Engine No. 2", but did not receive funding from the British government. His design was finally constructed in 1989–1991, using his plans and 19th-century manufacturing tolerances. It performed its first calculation at the Science Museum, London, returning results to 31 digits.<ref>{{Cite web |title=Babbage's Difference Engine No 2, 2002. {{!}} Science Museum Group Collection |url=https://collection.sciencemuseumgroup.org.uk/objects/co62748/babbages-difference-engine-no-2-2002 |access-date=2025-03-25 |website=collection.sciencemuseumgroup.org.uk |language=en}}</ref>

Nine years later, in 2000, the Science Museum completed the [[computer printer|printer]] Babbage had designed for the difference engine.<ref>{{cite news|url=http://news.bbc.co.uk/2/hi/science/nature/710950.stm |title=SCI/TECH &#124; Babbage printer finally runs |work=BBC News |date=13 April 2000 |access-date=27 April 2012}}</ref> His printers were the first computer printers invented.<ref name=":2" />

====Completed models====
The Science Museum has constructed two Difference Engines according to Babbage's plans for the Difference Engine No 2. One is owned by the museum. The other, owned by the technology multimillionaire [[Nathan Myhrvold]], went on exhibition at the [[Computer History Museum]]<ref>{{cite web | url = http://www.computerhistory.org/babbage/ | title = Overview&nbsp;– The Babbage Engine | publisher=Computer History Museum | access-date =29 January 2009 }}</ref> in [[Mountain View, California]] on 10 May 2008.<ref>{{cite news | last = Shiels | first = Maggie | title = Victorian 'supercomputer' is reborn | url = http://news.bbc.co.uk/2/hi/technology/7391593.stm | access-date =11 May 2008 |work=BBC News  | date = 10 May 2008 }}</ref> The two models that have been constructed are not replicas.