Plan 28 is working towards building Charles Babbage's Analytical Engine. For the latest news follow the Plan 28 blog.
The project has reached a long-awaited defining point. Tim Robinson has completed the first draft of the most comprehensive description yet of the Analytical Engine designs. We have for the first time both an aerial view that integrates partial and seemingly unrelated developments, as well as the most detailed analysis yet of the specifics of implementation.This analysis has been a prerequisite for the build. Babbage left no design for a complete Engine and the rationale for the ad hoc improvements made over thirty-eight years has not, till now, been fully investigated nor understood. We have lacked the necessary understanding to inform a meaningful build i.e. which signature features of which design should be combined to create a single representative machine.
Winding back to last Spring, with the survey of the Babbage manuscript archive complete, we were faced with the choice of pressing on to define what might be built using our current knowledge, or stepping back to evaluate and analyse what was captured in the review of the archive. We decided to step back and Tim Robinson has made substantial progress extending and integrating our understanding of the AE design and its trajectory from 1834 till Babbage’s death in 1871. Tim has identified and describes six phases in the evolution of the AE designs. The Babbage technical archive held by the Science Museum has been reviewed sheet by sheet so the reference sources of AE-related content are now known. After a short hiatus Tim Robinson is carrying out the same exercise on the Babbage material in the Buxton papers held in Oxford.
Tim Robinson has started writing up findings following the review of the complete Babbage manuscript archive. The initial work is in the form of an overview centred on each of the ‘Plans’ i.e. the large ‘systems drawings’ that Babbage shed during the evolution of the designs. The intention was to put to one side further detailed work, for the moment at least, to take stock and to document broad-stroke findings and new insights.
Excavating further the hardly-known Plan 30 (there is a Plan 28a but seemingly no Plan 29) proved irresistible both for inherent interest and for completeness. Babbage restarted work on the AE designs in June 1857 after a break of almost a decade and referred to the machine as ‘Analytical Engine 30’.