Fourth part of a file of photocopies of correspondence between Ernest Lenaerts and his managers at Lyons - John Simmons, W.J. Edwards and T.R. Thompson, during Lenaerts' secondment to the Cambridge University Mathematical Laboratory, working as part of the EDSAC team under Maurice Wilkes. 

Many of Lenaerts' original letters were written enclosing reports on the progress of the EDSAC team, but photocopies of the reports themselves were not included in this file of photocopies.  Presumably the original reports are included in the archive copy held at Manchester, ref. GB 133 EHL/2 EDSAC.

Comprises:
- 92-93. Photocopy of a draft/file copy letter from Ernest Lenaerts to John Simmons, 8th June 1948;
- 94-95. To Ernest Lenaerts from John Simmons,  11th June 1948;
- 96-97A. Ernest Lenaerts to John Simmons, 13th July 1948. [final page found in pile of unidentified fragments at the end of the file, now marked 97A];
- 98. To Ernest Lenaerts from John Simmons,  14th June 1948;
- 99-100. Ernest Lenaerts to W.J. Edwards (Engineers' Dept, Lyons), 16th June 1948;
- 101-102. Ernest Lenaerts to John Simmons, 18th June 1948.[The original photocopy is very faint];
- 103. To Ernest Lenaerts from T.R. Thompson (Chief Assistant Comptroller, Lyons), 14th July 1948;
- 104-105. Draft paper/notes by Ernest Lenaerts: Test Equipment for Electronic Workshop, 15th July 1948;
- 106-107. Ernest Lenaerts to John Simmons, 19th July 1948;
- 108. To Ernest Lenaerts from John Simmons,  19th July 1948;
- 109. To Ernest Lenaerts from John Simmons,  22nd July 1948;
- 110-111. (incomplete - first two pages only) Ernest Lenaerts to W.J. Edwards (Engineers' Dept, Lyons), 3rd August 1948;
- 112. To Ernest Lenaerts from G.J. Mills (Lyons),  5th August 1948;
- 113-114. To Ernest Lenaerts from W.J. Edwards (Electrical Dept, Lyons), 6th Aug 1948;
- 115-116. Ernest Lenaerts to G.J. Mills  (Lyons), 9th August 1948;
- 117-118. Ernest Lenaerts to W.J. Edwards (Engineers' Dept, Lyons), 10th Aug 1948;
- 119-120. To Ernest Lenaerts from T.R. Thompson (Chief Assistant Comptroller, Lyons), 12th August 1948.

Page numbers in red were added by Peter Bird.

Research comments: In Lenaerts' letter to Mr Edwards, who worked with John Simmons, on page 3 of this set of documents (dated 16th June 1948), Lenaerts refers to the need to "equip a suitable workshop for the job" of building a machine like EDSAC at Cadby Hall. At this point in time EDSAC is not yet working, and indeed Lenaerts reports "rather slow progress" although he does also say that of all the "machines being built here in this country, and also in America, that EDSAC is the only one showing signs of completion". That perhaps explains why Lyons already have every intention of building one of their own. 

Lenaerts reports that "in America in particular considerable difficulty is being experienced with the Mercury Delay Lines, whereas in our [the Cambridge lab] use the only "non workers" have been two short tubes" that sustained damage "on the journey from Cambridge to London and back for the Royal Society Exhibition" (page 9) [likely to have been the Royal Society’s Summer Science Exhibition, at which memory for an 'Electronic Digital Computing Machine’ was exhibited by the Cambridge Mathematical Laboratory in 1948]. This shows how advanced the Cambridge team felt themselves to be and also how interrelated all the computing developments were at this point in time, both in this country and in America.

That interrelated nature is continued in this set of letters on page 11, where Lenaerts reports that Professor Hartree is currently in America and is of the opinion that "progress in work on Electronic Computors in the U.S. is very much behind our work".

Page 14 and 15 of this set shows Lenaerts' thoughts on how the workshop at Cadby Hall should be equipped and staffed. Page 23 is a reply to this, which highlights the availability of government surplus equipment that the team can make use of and which Lenaerts embraces enthusiastically on page 28 in terms of purchasing specific valves for constructing LEO.

Page 16, dated 19th July 1948, records the visit to Cambridge by Dr Julian Bigelow from Princeton University who updated the team on the development of EDVAC, in particular "a new [wire] recording apparatus which seems to be the ideal form of intermediate memory for a commercial computor". Lenaerts reports that EDVAC is expected to be completed by the end of 1948, though to achieve that "they will probably have to discard the idea of using the Selectron form of memory" that clearly isn't working. Lenaerts' letter ends with optimism in that "The feeling here is that another milestone as been passed towards completing the computor [EDSAC]".

Page 22 is a letter from Geoffrey Mills of Cadby Hall to Lenaerts informing him of the developments being made at the Telecommunications Research Establishment (TRE) at Malvern under the guidance of Dr Uttley. Uttley's team were developing TREAC, one of the first parallel machines being developed in the country, which Lenaerts says he is aware of. On page 26 Lenaerts makes reference to "quite a bit of friendly rivalry" between the Cambridge and TRE labs " on the subject of electronic computors" as a result of Maurice Wilkes' work at TRE during the war. Lenaerts indicates that there are considerable differences between Cambridge's approach and TRE's, concluding that it would be "unwise to approach TRE on the subject of electronic computors unless at some future date we decide that the EDSAC model is unsuitable for our purposes".(LM)

Provenance :
The photocopies were originally requested by Peter Bird, as part of his research for LEO - The First Business Computer, and later donated to the NAHC, then transferred to CCH at the request of the LEO Computers Society for inclusion in their archive.