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If we wished to tag the respective roles of Babbage, Lovelace, and Turing, it would be fair to
say that Babbage’s interests were essentially hardware-led, Lovelace’s interests application-led,
and Turing’s, at least initially, theory-led, devising as he did a formal description of a computing
engine in logically rigorous terms.
Did Babbage and/or lovelace influence Turing?
Ideas explicitly articulated in the 19th century pre-echo with startling familiarity those of the
20th century, and this raises the inevitable question of influence. Did pioneers of the electronic
computer age reinvent core principles largely in ignorance of what had gone before, or was
there direct influence of some kind?
Babbage’s engines were a false dawn. With Lovelace’s early death automatic computation lost
a formidable advocate, and when Babbage died some twenty years later the movement lost its
most energetic practitioner. There were a few short-lived followers, but no heirs. Developmental
continuity was broken, and except for a few isolated twitches, interest was revived in earnest
only in the 1940s with the start of the electronic era.^27 Leslie Comrie referred to the gap between
Babbage and electronic computing as a ‘dark age of computing machinery that lasted 100
y e a r s ’.^28 There was no chain of intermediaries to the modern era through which to track influ-
ence: the baton was dropped and lay where it fell for a hundred years.
Studies show that most of the pioneers of the modern age knew of Babbage.^29 A few did not;
and at least one appears to have claimed to know more than he did.^30 The legend of Babbage
did not die, and what he had attempted was common knowledge to the small cadre of those
involved with automatic computation. So just what was known of Babbage and Lovelace’s works
by those who knew of them at all?
We know that Turing discussed Babbage with Donald Bayley at Hanslope Park after Bayley
was posted there in 1944, but too little is known about the content of these discussions to pro-
vide us with any conclusive view of the extent of Turing’s knowledge.^31 Similarly, there were
accounts of ‘lively mealtime discussion’^32 about Babbage at the Government Code and Cypher
School at Bletchley Park, which would not have pre-dated September 1939 when Turing
reported there at the start of the war. ‘Babbage was a household word and very much a topic of
conversation . . . very, very early on’ attested J. H. Wilkinson, Turing’s assistant at the National
Physical Laboratory during the design of the ACE computer in the 1940s.^33
What sources might Turing have had access to? There were several published descriptions of
Babbage’s his work in the public domain that went beyond general accounts of his work of the
kind found in encyclopaedias, or indeed in his own autobiographical outing, Passages from the
Life of a Philosopher, published in 1864. One was Lovelace’s Sketch,^34 which included specific
mention of the machine halting automatically at the detection of the all-zero state or a sign
change, and of course the idea of symbolic representation. A second was a large collection of
articles, book extracts, and a selection of design drawings collated by Babbage’s son, Henry, and
published in 1889.^35 A third was Dionysius Lardner’s article, published in 1834, which gave an
extensive account of Babbage’s Difference Engine No. 1, and in which there was explicit men-
tion of the machine being cycled to produce successive values of a formula, the detection of the
roots, and a bell ringing automatically to signal a solution.^36 Lardner’s article was both cited and
referred to in Lovelace’s Sketch. There was the comprehensive technical archive of Babbage’s
designs and notebooks held by the Science Museum in London.^37 No more than a handful of the