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

8 comments:

  1. I'm curious to know if there is a sense of possible future direction in the case that it is found there is no complete design. If, after all the documents are scanned and analysed, it is found that critical systems were not designed, or their design is untenable, will the project attempt to fill those gaps, or simply publish the results and stop?

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    1. We would fill the gaps. There are cases of straight omission - where Babbage went far enough to establish a viable design but omitted detail of drive and control. These are gaps that would be filled by best-case adherence to techniques Babbage had used elsewhere or, where there are no cues, to design mechanisms ourselves informed by practices of the day where these exist. This was the approach used successfully in the construction Difference Engine No. 2 though the scale of what is needed in the AE is many times larger. These cases of underspecification were anticipated. There are other categories requiring interpretative: there are designs that are complete or near complete that are not always consistent. Babbage would make changes or develop aspects of the designs not necessarily compatible with what had gone before but not go back to update the whole ensemble. Here we would have to modify designs to harmonise the original elements. Finally, there instances of multiple specified designs for the same function but with no final choice. Here we would have to make informed selections, mixing and matching. 'Untenable' designs we would modify to correct or produce designs that are functionally equivalent. We have not yet encountered a missing 'critical system' that Babbage did not in some way address that invalidates the prospect of an historically meaningful construction.

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  2. Thank you for the update.
    Do you have any pencilled-in timeline for the next steps?
    Glenn

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    1. We have a workplan for the next three years which includes publication and experimental modelling. The timing depends what we find in the final stages of the review of sources.

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    1. Yes, but we will need to decide what to model, and how. The late-period carriage as embodied in the 1871 piece is a strong candidate. There are multiple versions, not least for both whole zero and half zero. We need first to complete the survey of uncatalogued material as there is relevant material there. So, definitely yes, but not quite yet.

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  4. Once completed, will the database be made available to the public?

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  5. The database was developed as a research tool to support Babbage studies. The spirit of the project is educational and historical so the intention is to share in the service of these aims. But not necessarily through unconditional open access. There would need to be tiered privileges for alteration, new content would need to be moderated, and protocols in place for attribution and acknowledgement. We are addressing these issues in anticipation of putting the effort into technical understanding once the review of sources is complete.

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