Babbage Difference Engine

The best explanation of the construction and opreration of the machine is in the first video I have linked showing Difference Engine No. 2 (see Nomenclature section below) loaned to the Computer History Museum on 2008.

The second video shows a Difference Engine in operation. This is the first one built which is at the Science Museum in London. This early video isn't of the same high quality as the first but it does show the machine being cranked. The Difference Engine in this video doesn't have the output module (which contatains twice as many parts as the main engine).

The two videos therefore show the only two Babbage Difference Engines ever built. Charles Babbage never managed to build a full engine himself, largely for financial reasons. However, the engines have been built using Victorian technology from his original plans and prove that had he raised the money to do so, he could have built a fully working engine in the 18040s.

The best text on Charles Babbage and his Diffenence Engines is the Computer History Musuem microsite on this topic. This has biography on Charles Babbage, explains how a Difference Engine is used for calculations and has some background on the two modern machines. If you prefer, I have also linked the relevant Wikipedia articles.

There is some confusion over the label "Difference Engine No 2." Sometimes (such as in the Wikipedia article) this is used to refer to an even more advanced design by Charles Babbage for the Analytical Engine. That design has never been built. In this lens, Difference Engine No. 2 is used to mean the second Difference Engine design by Babbage, not the more advanced Analytical Engine. Difference Engine No 2 is actually the latest of the 3 designs by Babbage.

Two modern engines have been constructed. It would be possible to label these engine number one (Science Museum London) and enginge number two (Computer History Museum / private collection) to reflect the order in which they were built but that could cause confusion and has been avoided.

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For most of my lenses, I include a lot of text within the lens. In this case, the external sources, particularly the videos, are so much neater than any text I could add, so I have instead relied on links. I was lucky enough to see the engine in operation at the Computer History Museum and it was wonderful. Apparently the sponsor's wife doesn't want it to smell of metal and oil when it is moved to their house so it lubricated using olive oil!

Kate