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

Tuesday, May 23, 2017

Spring 2017 report to the Computer Conservation Society

Doron Swade gave an update on Plan 28 to the Computer Conservation Society on May 19 as follows:

Excellent progress to report on the database for the Babbage technical archive. Tim Robinson in the US has produced a searchable database of all catalogued material with related content fully cross-referenced. Each item links directly to the corresponding Science Museum catalogue entry and to the recently available (low resolution) online scans of the originals. This work covers all technical drawings and related Notations (there are some 2,200 Notations for the Analytical Engine). A small amount of material that is known to exist but that is not yet in the Science Museum catalogue remains yet to be done.

Back in London I have completed a review of the 26 volumes of Babbage’s Scribbling Books – Babbage’s scratchpad daybooks. The Scribbling Books comprise 8,100 folio sides each of which has been examined for relevant content. The specific purpose of this review was to identify all material specifically relating to the Mechanical Notation, Babbage’s language of signs and symbols that he used to describe and specify his engines. At the same time other content relating to known unresolved questions was logged. The logs are intended as a retrieval and navigation tool to support ongoing research into the notational language with a view to further decoding the Analytical Engine designs.
It is thought to be only the third time in history that the set of Scribbling Books has been gone through in their entirety. The only known precedents for this are the work of the late Bruce Collier, and the late Allan Bromley in the late 1960s and 70s.

The next step on the main database is to systematically go through the Scribbling Books and extract all cross references, tag subject content and transcribe significant material. This process is expected to be completed by the end of the year.

Doron Swade

Friday, January 20, 2017

Winter 2016 report to the Computer Conservation Society

This was presented on January 19 to the Computer Conservation Society by Doron Swade.

The main activities since last report focus on the original manuscript sources of the Babbage technical archive held by the Science Museum. Since the 19 th century there have been several generations of reference systems, and with the digitisation of the archive in 2011 by the Science Museum, a further layer was added. The reference system now used by the Science Museum will be the de facto standard for future scholarship.

What we are doing is reviewing image by image the entire archive holdings (some 7000 manuscript folios) which include all surviving drawings and notations for the Analytical Engine, to reconcile their filenames and titles with the three or four earlier reference systems, to identify anomalies, relate the descriptions to the physical sources for untraced or missing material, identify phantom entries and omissions, and resolve situations in which material is known to exist or have existed for which no physical source is evident. Not all of this is straight forward and in some instances unscrambling layered inconsistent reference systems dating back to Babbage’s time has proved to be nightmarishly difficult. Several visits to the physical archive at Wroughton have been made. More will be required.

The outcome of this process will be a searchable data base, annotated and cross-referenced, that identifies all known sources, and records the status of each source including issues of provenance, anomalous reference history, with a record of links and citations to other material in the archive and elsewhere.

As reported in September, Tim Robinson in the US is going through all known material sheet by sheet to construct the searchable data base with estimated completion by the end of 2017. In London I am going through 20 volumes of Babbage’s ‘Scribbling Books’ page by page, transcribing AE-relevant material, to produce a searchable quick index, estimated for completion by July 2017.

We are in close collaboration with the Science Museum archivists, and our findings are routinely supplied to them in support of their ongoing work to open-source this material. The main outcome to the Analytical Engine project will be a survey-knowledge of all known material relevant to the AE design, consistent indexing, and a powerful software retrieval and reference tool.

While this activity is ongoing we have intermitted our efforts to reverse engineer a more complete understanding of the Analytical Engine design though, it must be said, pursuing the implications of critical new discoveries has proved, on occasions, irresistible.

Doron Swade