Friday, March 17, 2023

Spring 2023 report to the Computer Conservation Society

Project Report to Computer Conservation Society Committee for 16 March 2023

It has been a while. So, a brief recap on where we are and what we propose to do.


The mission of the project is to build a Babbage Analytical Engine for historical and educational purposes. Babbage left no single definitive design for an Analytical Engine. Instead there are drawings (called Plans) Babbage drafted to record developmental staging posts as his ideas evolved over a period of some 40 years. We regard an understanding of these Plans, and the design trajectory they represent, as a prerequisite of what could meaningfully be built i.e. which signature features of which design we should combine to create a machine that would best convey Babbage’s conception of an automatic digital general purpose computing machine in the 19th century. 

In November 2021 I reported that Tim Robinson in the US had had completed the most comprehensive description yet of the Analytical Engine. The work is a product of five years research founded on a detailed review of the entire Babbage technical archive. The work analyses the workings, design and development of the machine, with a running evaluation of levels of conception, completeness, and of mechanical detail. The account runs to some 120,000 words and describes six phases of development from 1832 till Babbage’s death in 1871. 

Since then, Tim has extended the analysis with a description of the Selecting Apparatus, a key feature of how Babbage implemented division using the selection of multiples of the divisor to be subtracted from the dividend to determine each next digit of the quotient. The description of the designs and their development, adds some 6,300 words to the earlier account. With the addition of this description, the whole account positions us to finally advance the project to the next stage – specifying what to build.

Way Forward

We need to expand the team to include expertise we currently do not have: animation and modelling skills for simulating mechanisms, and that of mechanical engineers. In February 2022 we sought to grow the team by inviting a promising party to engage and collaborate with Tim to develop and refine the account so that it could serve as an induction and briefing document for new team members, and as the foundational reference source for design and construction. By October 2022 it was evident that this first recruiting attempt had not ignited. 

Putting in the time and effort into preparing Tim’s account for release into the public domain would have the significant benefit of capturing and preserving the substantial advances in understanding, allowing it to serve as a launching pad for subsequent implementation. Preparing the treatise for publication for use by others would well serve both history and Babbage studies but would delay implementation by several years. The loss of momentum this would entail is a significant concern.

We need to attract new people committed to the mission of building a Babbage Analytical Engine and motivated to engage in the technical design challenges. We then need to attract resources to fund the project. There is currently no organisational body or institutional structure in whose name we can do this, or that can host the project or its future team. 

So we propose to release, in piecemeal form, summary findings of Tim’s account. We propose to do this through this Website (which has carried progress reports of the project, and is the main platform of communication with the community of people who have so far expressed interest in, and support for, the venture). Tim will post installments each month summarising his descriptions of the design, insights into Babbage’s thinking, challenges, difficulties, and analysis. We hope that by sharing exposure to Babbage’s thinking in this way, an appreciation of this remarkable unbuilt machine will spread and reach those motivated to participate in its physical realisation.

Doron Swade