Friday, February 18, 2022

January 2022 report to the Computer Conservation Society

Last November I reported on the successful completion of the first draft technical description, by Tim Robinson, of the Analytical Engine designs. Since then we have initiatives underway to increase the size of the team to take this work further. We have a separate initiative to view working papers donated by Anne Bromley, Allan Bromley’s widow. Allan Bromley, Australian computer scientist, died in 2002. His work was the first attempt to study of the detail of the Analytical Engine designs. Our study of the new Bromley papers will enable us to assess of the scope and depth of his researches and to key Tim Robinson’s findings into what was known before.

Doron Swade

Monday, December 6, 2021

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



Sunday, September 19, 2021

Autumn 2021 report to the Computer Conservation Society

Submitted by Doron Swade to the Computer Conservation Society.

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.

These are framed in an overview of the developmental timeline of the whole AE enterprise. There are also focussed pieces on central topics including the use of punched cards, the user view, methods of carriage of tens, and arithmetical process. This work represents the first comparative overview of each of the major designs ('Plans') and provides a new depth of understanding of the overall AE designs and of the developmental arc. The new findings vindicate the decision to take time out to process the material from the archive survey: the work will inform what can meaningful be built given that none of Babbage’s original designs describe a complete engine; secondly, the scholarly value of capturing and documenting a major advance in understanding since Bruce Collier’s work in the 1960s and Allan Bromley’s work in the 1970s and 80s. The immediate next step is to complete this analysis. The project will then move on to defining what version of the AE should be built.

Doron Swade

Thursday, March 25, 2021

Spring 2021 report to the Computer Conservation Society

Submitted by Doron Swade to the Computer Conservation Society.

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’. Tim reports that the hardware changes introduced for Plan 30 are ‘dramatic’. One remarkable feature is the extension of the Store to 1000 registers, and most intriguingly various methods of mechanically addressing the store contents. The broad-stroke writing has been paused temporarily while this rich seam is explored. It is not expected to take long and we look forward do the resumption of the interpretative account.

Doron Swade 

Tuesday, February 2, 2021

January 2021 report to the Computer Conservation Society

Presented by Doron Swade on Monday 21 January 2021 to the Computer Conservation Society.

With the first-pass inspection of the manuscript archive complete, attention has turned to analysis and interpretation, and organising the findings to aid navigation. Babbage shed versions of the design as it developed in the form of ‘Plans’ – large ‘systems drawings’ which serve as developmental staging posts – the main ones of which number Plan 1 through to Plan 28. The overall approach to analysing the accumulated data is that of a timeline that groups all material, from wherever in the archive (drawings, Notebooks, Notations), to each of the landmark Plans.

The significance of the design advances for each Plan is identified as each is reviewed and evaluated, whether, for example, a new Plan involves a major design reset or only incremental change. From this, the first fruits of the extensive study of the sources are now emerging and the overall developmental arc is now easier to identify. A major initial finding is that the designs are less disjointed than thought and there is more continuity in the inventive trajectory than we feared was the case, or that scholarship to date had indicated. As an example of a more specific finding: it is not until Plan 27 that there is the first evidence of user-level conditional operation. While the Analytical Engine is routinely portrayed as incorporating, from the start, defining features of a modern computer conditional operation included, this feature appears fairly late in the day and is barely mentioned again. How significant to Babbage was conditional operation as a defining feature, is now an enticing open question.

This work is being undertaken by Tim Robinson in the US. Progress was slowed in by climate crises in California not to mention political and pandemic disruption. The initial findings are a long-awaited reward after some four years examining primary sources.

Doron Swade

Monday, June 1, 2020

Spring 2020 report to the Computer Conservation Society

Presented by Doron Swade on Thursday 14 May 2020 to the Computer Conservation Society

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. This material is of particular interest not least because there are several essays Babbage wrote on the Analytical Engine while in Italy immediately after his visit to Turin in 1840 where he gave his first and only seminar-lecture on the Analytical Engine at a convention of mathematicians, surveyors and scientists. This rare engagement with others was a significant stimulus to Babbage so his writings immediately following this are of special interest. We have done two substantial photo shoots (2015, 2016 and 2018) of this manuscript material, so digitised images are to hand. Part of the difficulty with is that the manuscripts are unsympathetically bound (text lost in the binding gutters), some material is undated, and the manuscripts are not bound in chronological order. We are also currently planning on the best way to document the findings so far, for wider dissemination - this a lesson learned from the material left by the late Allan Bromley who regrettably published only a small part of his deep understanding of the AE design.

Doron Swade

Friday, September 20, 2019

Autumn 2019 report to the Computer Conservation Society

This was presented by Doron Swade on September 19, 2019 to the Computer Conservation Society

In a visit from the US in March Tim Robinson reviewed a collection of ‘mystery’ material consisting of content that had eluded listing or cataloguing in earlier programmes by the Science Museum, and by Allan Bromley who produced, in 1991, the first near-comprehensive listing of the Babbage technical archive.  Logging this last cache of material is now complete and it appears that only about a third of the original material survives. This estimate is based on references in the Sketchbooks to material that should be in this cache but were not found there, or elsewhere. Findings have been shared with Science Museum archivists accompanied by suggestions of how this material might fit into the structure of the new Babbage catalogue, available now online, created by the Science Museum. There is material in the Buxton archive in Oxford that awaits attention but the primary technical archive of Babbage papers held by the Science Museum has now been viewed and relevance to the AE design logged.

With the archive review essentially complete, a process that took over three years, Tim has shifted attention to developing a simulation environment to describe, explore, and verify the mechanical designs. So far this involves ‘logical’ simulation which features aspects of Babbage’s Mechanical Notation, the language of signs and symbols he devised to describe the machines and as a design aid, not unlike a later Hardware Description Language (HDL). Features of the Mechanical Notation that are reflected in the simulation tools include the notion of a ‘piece’ (an aggregation of parts that acts or is acted on as an ensemble), ‘working points’ (the points of influence and action between pieces), ‘assemblies’ and ‘connections’. It is hoped that this high-level simulation will be extended in due course to solid modelling and techniques for visualisation as a design aid, a manufacturing front-end, and for education.

Doron Swade