Feedback Systems with Periodic Loop Closure: Case 37003; File 36690-2 MM-44-110-32 [Bell Laboratories Technical Memorandum]
Murray Hill, N. J. Bell Telephone Laboratories, Incorporated March 16, 1944. Later printing. One Memorandum group highlighting three different reproduction techniques, all 10 7/8 x 8 3/8 inches.
1) One leaf. Printed "Cover Sheet for Technical Memoranda" form on thin translucent typewriter paper (watermarked "Esleek Superior Manifold"). Names, subject, abstract, etc are a typescript carbon copy. Four holes punched at the spine.
2) -3 pages printed on verso only + one leaf ( containing 3 figures ). Ditto'd (spirit duplicated) with purple ink. An inked correction to MM number is present on page .
3) the last leaf is a Plate. Positive blueprint with sharp blue ink lines. The verso has a circular inked stamp with "Printed (?) | Sep 21 1944 | New York".
The five leaves are held together with a short square metal paperclip with associated creasing. Near Fine. Wraps. 
There were five examples of this paper in Shannon's files with a small penciled note clipped to them: "9/21 Miss Wiggins : Attached are 5 more copies as promised. M. K. C." This example (our stock #28974) includes a modern copy of that note.
"In the design of a system for automatic frequency control, the question of stability criteria for a feedback system whose loop is closed periodically for short intervals has arisen..." (first page).
Cover Sheet Abstract: "Conditions are derived analogous to the Nyquist criterion for stability in a feedback system which is closed periodically for short intervals of time." Eight Bell Lab scientists are on the distribution list.
PROVENANCE: The personal files of Claude E. Shannon (unmarked). Five copies were found in Shannon's files. One example with an original typed Memorandum cover and penciled note. The other four [as here] with typescript carbon of the Memorandum cover sheet.
Sloane and Wyner, "Claude Elwood Shannon Collected Papers," #18