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

Friday, March 22, 2019

March 2019 report to the Computer Conservation Society

This was presented on March 21, 2019 to the Computer Conservation Society by Doron Swade.

The sheet-by sheet inspection of Babbage’s vast technical archive is now in the end game after some three years.  The last progress update reported that Tim Robinson, in the US, working from the digitised images of the manuscripts, was close to completing a review of the known catalogued material in the Science Museum archive and that one of the final tasks was a scrape of a relatively small but potentially critical set of drawings that had not been catalogued or scanned the contents of which are largely unknown.  Tim is currently in London spending a week going through this material.  This material evaded the Science Museum’s scanning operation in 2011 largely because it was not listed in the catalogue prepared by the late Allan Bromley who compiled the first near-comprehensive record, published in 1991, of the Babbage technical archive.

There have already been significant finds.  The Notations for Difference Engine 1, dating from 1834, thought to exist, had never come to light.  These have now been found and represent a crucial piece in the puzzle of the developmental trajectory of the symbolic language Babbage developed as a design aid, to describe and specify his engine, and used extensively in the development of the Analytical Engine.

Equally significant is the discovery of what is thought to be the legendary Plan 28a, part of the most advanced design for the Analytical Engine.  There have been references to Plan 28 and Plan 28a designs peppered through the late manuscripts and some design drawings, but the existence of this plan has never been confirmed.  Bromley told me in the late 1990s that he questioned whether it had existed as a separate entity in the first place in which event ‘Plan 28’ may have been a federation of improvements added to previous designs.

The survey so far has identified mis-titled drawings, single drawings that have two unrelated catalogue entries, and drawings known to exist from earlier scholarly work but not located.  These findings are openly shared with the Science Museum archivists in what has become a model collaboration between content specialists and archivists. We await the completion of this week’s inspection in the hope and expectation of more surprises.

Doron Swade

Saturday, January 5, 2019

Autumn 2018 report to the Computer Conservation Society

This was presented on November 15, 2018 to the Computer Conservation Society by Doron Swade.

The end is in sight creating the cross-referenced database for the set of some 20 Scribbling Books, the manuscript notebooks in which Babbage recorded his workings and thoughts on his engine designs. Tim Robinson, who has been compiling the database is up to the last year of Babbage’s life (1871) and is within striking distance of completion. The process has taken coming up for three years.

The motive for this undertaking was that before we could commit to building anything we needed to be sure that we had reviewed everything Babbage had to say on a particular topic. The situation is confounded by Babbage’s practice of returning to the same design issues time and time again over periods of decades as a consequence of which related material is unsystematically scattered through the archive of some 7,000 manuscript sheets.

While Tim Robinson’s emphasis so far has been data capture rather than interpretation there are several general preliminary findings that are already invaluable to the overall enterprise of constructing an Analytical Engine. One such is the confirmation that not only are the designs incomplete with respect to details of control and overall systems integration (this was anticipated) but that there are several critical features for which there are worked viable alternatives the final selection of which Babbage left open (method of multiplication, digit precision, method of carriage, for example). Also, that Babbage remained creatively active till the end with at least one instance of his most sophisticated design being modelled in the period immediately before his death in 1871.

The completion of the database will be a landmark in the developmental trajectory of this project. Next steps are, firstly, a scrape of a relatively small but potentially critical set of ‘mystery’ drawings that have not been catalogued or scanned. This is a manageable clean-up job undertaken for completeness and in the hope that some final gaps might be filled and some remaining blind references traced. Secondly, to model and build a mechanism (the advanced anticipating carriage mechanism) to assess logical and physical feasibility, and to use this to develop generic modelling and evaluation techniques to be extended to each of the core functions. 

Doron Swade

Friday, May 18, 2018

Spring 2018 report to the Computer Conservation Society

This was presented on May 17, 2018 to the Computer Conservation Society by Doron Swade.

Work continues on the cross-referenced database for Babbage’s Scribbling Books, the set of manuscript notebooks Babbage used to record his daily deliberations. The database marathon has been undertaken by Tim Robinson in the US and the most recent work takes us to the mid-1860s (Babbage died in 1871). Tim reports that this later content is fragmented and not as systematically referenced by Babbage to the mechanical drawings as is his earlier work. This kicks the interpretative can down the road somewhat as once the transcriptions are complete this content will need to be revisited to integrate it into the larger picture. Page-by-page inspection, while exacting, has the rewards of close reading one of which is revealing new content in the cracks. Here is one such: in the context of manufacturing methods Babbage calculates that the total number of teeth to be formed for a store with 1,000 registers would be 1,800,000.

The Science Museum’s small store at Blythe House has been cleared and a missing Scribbling Book has come to light. A microfiche from the 1970s, illegible in places, was all that was thought to have survived. The Museum generously made the re-found volume available at its excellent viewing facilities in the Dana Centre, South Kensington, and we have photographed the volume using a copying rostrum as an interim measure to resolve by comparison unclear material in the microfiche. The Museum intends to digitise the volume in due course and add it to the online digital archive.

A new development comes in the form of Pip Meadway, a volunteer who has generously been transcribing manuscripts. Using captured digital images of the sources he has transcribed material from the Cambridge Scribbling Book. He is currently working on images of the essays on the Analytical Engine Babbage wrote while travelling in Italy after his memorable visit to a convention in Turin in 1841 where he gave his one and only lecture on the AE designs. The manuscripts are in the Buxton archive in Oxford and the archivists kindly allowed image capture for the transcription work.


Doron Swade

Monday, March 19, 2018

March 2018 report to the Computer Conservation Society

This was presented on March 15, 2018 to the Computer Conservation Society by Doron Swade.

Work continues on the cross-referenced database for Babbage’s Scribbling Books, the set of manuscript notebooks Babbage used to record his daily deliberations.

Our original intention in supporting the wider release by the Science Museum of the Babbage technical archive was to enlist, in due course, the support of a wider community of interested volunteers. Until recently we have not taken up generous offers of help largely because it was not evident how our limited resources could stretch to manage an extended programme of work and to give the new input appropriate attention. A new development has been to make available for transcription by an enthusiastic volunteer images taken of the Scribbling Book held in the Cambridge Library. This trial programme has prompted us to address a number of issues: access to material that is on conditional release to the project by institutional archives; usage rights and access to the database; rights to edit, amend or add material; issues of attribution and checking to maintain the integrity of the content; and the formalisation of editorial conventions for database entries. The experiment has provided a valuable opportunity to address these and related issues in preparation for enlisting wider participation when we return to the task of interpreting the new indexed material to make a final assessment of the designs and the extent to which the material supports a consistent description of a complete machine.

The Cambridge manuscript belongs to Babbage’s later period (1850s and early 1860s) when he returned to refine and develop his earlier work. The most substantial single section consists of some 65 manuscript pages the transcription of which is now complete. Tim Robinson has vetted the transcriptions and incorporated them into the database. Preliminary review of this new material suggests that while cryptic in parts it is more coherent than previously thought and contains some potentially dramatic simplifications of implementation. This material will be the focus of close study in due course.

Doron Swade

Monday, January 22, 2018

Winter 2017 report to the Computer Conservation Society

This was presented on January 18, 2018 to the Computer Conservation Society by Doron Swade.

Work continues compiling the searchable database for Babbage's manuscript Notebooks. This work is being done by Tim Robinson in the US. It has till now been impossible for Babbage scholars to come to definitive conclusions about aspects of the Analytical Engine design because of uncertainty as to what the Notebooks contained: we could not know whether what had already been researched was all that Babbage had to say on any particular topic, nor could we assess the degree of completeness of the designs in ignorance of what else there might be in the some two dozen volumes of his manuscript Notebooks. Digging in the final cracks has been rewarding though we have resisted spending too much time interpreting the content given that the major immediate priority is data capture and cross-indexing. 


The question of the levels of completeness of the various designs is critical to a prospective build and new clues have emerged from the recent work. A manuscript in the Cambridge University Library contains a disconcerting observation by Babbage: that 'when some great improvement arose I only worked out enough to satisfy myself of its truth. I reserved the enquiry into many of its consequences as a treat when I otherwise felt indisposed to work' (1860). This has bleak implications for a definitive detailed design. 

Tim Robinson’s mining of the Notebooks revealed an entry in which Babbage refers to Plan 13 as the 'most complete ever made' (1849). So we now have a datum set by Babbage himself by which to judge the best expectation of completeness and this promises to give us a first approximation of the size and nature of design gaps we might need to fill in the specification of a meaningfully buildable machine. 

Continuing mining the Notebooks for the searchable cross-referenced database remains the priority for the coming months.

Doron Swade

Thursday, November 16, 2017

Autumn 2017 report to the Computer Conservation Society

This was presented on November 16 to the Computer Conservation Society by Doron Swade.

Work has continued steadily going through Babbage’s manuscript Sketchbooks (his working notebooks) and building up the cross reference database. As reported previously the volume of material is substantial and its organisation is not conducive to systematic study: it not indexed or themed by topic, nor is it rigorously chronological. Time and time again Babbage revisits the same or related topics over a period of decades, and these entries, many of which are cryptic, are dispersed through the twenty-five volumes comprising some 7-8,000 manuscript sheets. The cross-referenced database is being developed by Tim Robinson as a key research tool to manage this distributed content. 

The focus for the last six months has been on the volumes most relevant to the Analytical Engine design started in 1834. Happily this main sequence of books is, for the most part, in chronological order. We have just completed Volume 5 which covers 1841–1844, and includes the most intense period of work by Babbage on Plan 28, the most advanced design for the Analytical Engine.

There are notable gaps corresponding to periods when Babbage was travelling. There is a separate "Travelling Scribbling Book", which has not yet been studied in detail, and we know of a significant body of manuscript material in the Buxton archive at Oxford which was written while Babbage was travelling in Europe in the early 1840s. The intention is to fill these gaps in due course. 

While focussing on building the database, we have resisted the temptation analyse the material as we go as such analysis will be substantially assisted once the full corpus is in searchable form. Having said which, there are already new findings. A landmark drawing is Plan 25, dated 5 August 1840, which depicts the "Great Engine". This Plan provides the most complete system overview of the state of play at that time and is the most well-known of Babbage’s technical drawings. The version of the machine in Plan 25 is that Babbage presented in Turin in 1840 and on which Menabrea based his published description, which in turn prompted Ada Lovelace's famous Notes. The new finding is that there is no evidence of "user level" conditional control in this defining version of the design, this despite provision for sophisticated multi-way conditional branching at the "microcode" level. Given that the 1840 version was incapable of user-programmable conditional branching, the machine described in Plan 25 should be regarded technically as a calculator rather than a computer in the modern sense.

The first evidence of user-programmable conditional branching appears in an entry dated 19 March 1842 in what Babbage called the "minor operations" – ascertaining if a variable is zero, and ascertaining if a variable is + or -. This was when Babbage was well into the design of the "Small Analytical Engine" – a reduced version described in Plans 26 and 27. Work on Plan 28 (yet another complete reset) started two months later, but these “minor operations”, essential to making a "universal" machine, were carried over unchanged. It is yet to be established what suddenly triggered the addition of these operations. Babbage himself gives no hint of the reason in the Sketchbooks studied so far. 

Some 2,100 pages have so far been cross referenced, indexed, and transcribed into the database. Though this represents only about a quarter of the total manuscript material, we are much further than a quarter of the way through the process: most of the remaining volumes are more fragmentary, contain material not related to the Analytical Engine, or contain rough drafts later transferred to the drawings and/or the notations (textual content already captured). All the remaining volumes will be worked through though these are not regarded as a priority at this time.


Doron Swade