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Book: The Difference Engine

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The Difference Engine
Charles Babbage and the Quest to Build the First Computer
by Doron Swade

I found this book very interesting, because it balances to opposite goals: demonstrating the novelty of Babbage's ideas/vision, and showing that they had absolutely no effect on the emergence of computing. These opposing goals are laid out upon a modern day challenge: building the Babbage's previously unbuilt Difference Engine and proving that it was functional to Babbage's original design. As a computer scientist, the balance of historical background and engineering challenge made the book rewarding for me to read.

The extended entry contains outline and summary (massive spoilers).

Main Points:
1) Difference Engine was functional to Babbage's designs
- required 'mirroring' (reversal of components) and other minor fixes, but Babbage most likely would have caught these mistakes.
- High tolerences that Babbage specified were necessary
- thus, manufacturing technology was a bottleneck and barrier to the original engine's completion

2a) Babbage had no link to the modern computer
- Scheutz Difference Engine, which was inspired by Babbage, failed to be a success.
- Aiken (Harvard Mark I) claims influence of Babbage. It's unclear if Aiken's remarks were sincere, or if he was trying to link himself to Babbage's name and legacy.

2b) Babbage may have in fact delayed development and adoption of computers
- Swade is not the author of this thesis
- His failure made investment by the Treasury in similar projects taboo. IHMO, this is a British-centric support, and perhaps ignore effects in mainland Europe
- Designs for Analytical Engine were not publicized and were incomplete
- thus, Babbage's ideas of the Mill and Store could not have contributed to the scientific community.
- Corollary: Babbage had very little impact on mathematics, either, with no theories to his name

3) Ada Lovelace has been exaggerated by history
- Her only role was to publish report on the Engine
- Ada was not the 'first programmer.'
- Programs she publishes were contributed by Babbage and written long before she started her article
- Design of engine complete before she was involved
- Ada had only rudimentary mathematics background at the time she worked with Babbage
- Very narcissistic

4) Remarks on Babbage's personality

Habit of making direct, impolitic attacks that led to his exclusion
- yet, during the funding of the Difference Engine, was well supported by his friend's in the Royal Society
- attacked individuals directly in many of his writings, blaming them for Difference Engine failures

Very binary in his relationships
- Enemies of his were despised thorougly
- Friends could do no wrong

Felt Britain did not properly promote or reward scientific work, and that science in Britain was falling behind
- Felt under recognized
- Very popular in social circles. Frequent and sought-after dinner guest and held regular parties at his place where scientific inventions were displayed

Perfectionist
- Analytical Engine designs never finished

Opposed to patents
- shared his many inventions with the community

Airy
Babbage viewed him as his personal opponent

Recommended against Babbage's engines
- Babbage through there was a conspiracy by Airy against him because of Babbage's support of a friend in a defective telescope lens trial
- Airy felt that tables were not done frequently enough by the Astronomical Society to justify the cost. Human computers were more cost-effective.
- Airy felt that real value in an engine would be to detect errors using repeated subtraction, instead of generating new ones with repeated addition

Career
- Opposite of Babbage
- Career public servant
- Chief scientific advisor to the government
- Direct of the Royal Observatory at Greenwich
- Astronomer Royal
- Highly accomplished within the government

Later attacked for overlooking chance to discover Neptune

Doron Swade
- author
- Curator of Computing, Science Museum in London
- helped build first full working model of Difference Engine along with Allan Bromley, Reg Crick, Michael Wright, and Barrie Holloway

William Farr
- Chief statistician at General Register Office

Scheutz difference engine
1833: Georg Scheutz read descriptions of the principles of Babbage's engine.
- inspired to design engine of his own
- did not have any details of actual mechanical components
1837: Georg Scheutz's son, Edvard, offered to build the engine
- Edvard only 15 at the time.
1843: First prototype completed
- first machine completed in 1843
- included working printing mechanism
- only three orders of difference
- Prototype built with wooden frame using a lathe and hand tools, as opposed to the advanced techniques of Babbage's engine.
1851: King Oscar of Sweden approved funding of a engine
- 283 pounds
October 1853: Scheutz Difference Engine completed.
- four orders of difference to fifteen decimal places
- four times as slow as Babbage's
- more delicate than Babbage's
- By this time, Babbage had given up on building an engine of his own.
1855: Gold Medal at the Great Exposition in Paris
1857: Original Scheutz engine sold to Dudley Observatory in Albany, NY.
- unused
- now in the Smithsonian
1857: William Farr succeeded in having a copy of the Scheutz Engine built for the General Register Office.
- Intended for production of the English Life Table

1859: Copy finished, over budget and over deadline.
- Scheutz's engine had to be constantly monitored.
- didn't contain any of Babbage's safeguards
- not error-free

1864 English Life Table
- Of the 600 printed pages:
- 28 fully calculated and typeset by the engine
- 213 pages partially calculated and typeset
- the rest done by hand
- According to Her Majesty's Stationary Office, if the entire volume had been produced by the machine, it would have only resulted in ten percent savings.

Babbage helped promote Scheutz engine.

Georg Scheutz
Lived in Stockholm
Printer
Inventor
- advanced high-speed printing press
- steam turbine
- chemical dyes
- optical instrument for copying
- drawing apparatus
- brick-laying method

Unlike Babbage, Scheutz saw the engine, rather than the tables, as a marketable product.

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This page contains a single entry from kwc blog posted on December 16, 2002 12:22 PM.

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