Winter 2021 report to the Computer Conservation Society

Project Report to Computer Conservation Society Committee for Meeting Thursday 18 November 2021

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.

The treatise, which is a product of five years research founded on a comprehensive review of the entire technical archive, describes six phases of development from 1832 through till Babbage’s death in 1871. At user level, Tim describes and analyses the use of punched cards, the designs for the ‘Great Operations’ (multiplication, division, square root), and for the ‘Small Operations’ (including addition, subtraction, and stepping). The description and running analysis run to some 120,000 words and includes close studies of selected mechanisms. 

Our immediate next step is to structure and edit the material into a form usable by others. This is both to ensure the preservation of the knowledge the document represents, and to provide a working datum for the next stage. We are seeking to appoint someone on a funded basis to collaborate with Tim to produce a document to publishable standards.

In parallel with this we are set to examine the working papers of the late Prof. Allan Bromley. Anne Bromley, Allan’s widow, has donated three large binders of material to the Science Museum and we have made arrangements to access this material at the Science Museum Library in the Dana Centre in South Kensington. The Science Museum has kindly permitted us to copy the material for research purposes. 

Bromley’s publications on the Analytical Engine are masterful, invaluable but regrettably sparse and the extent of his very considerable understanding of the designs is certainly underrepresented in his published output. The examination of these papers will, it is hoped, corroborate our new understanding as well as reveal just how far he had succeeded in decoding Babbage’s intentions.

Doron Swade