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This is a rare photograph of a field communications center showing
a soldier using a wooden slide rule transposition cipher device.
A number of EE-8 telephones can be seen lashed to the uprights of the truck,
as well as a lineman's safety belt and other paraphernalia of field communications.
(Photo by Bernard Hoffman. Originally published by Acme and Cleveland Press
News, Official Life Magazine Photograph).
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This is an enlargement of the slide rule device. (Above text and photos courtesy of Snyder's Treasures < snyderstr@aol.com> . This item was put up for sale on E-bay).
Stephen A Kallis, Jr. offers some background
information. "The generic name for such gadgets is the St. Cyr Slide (or
Sliderule). It's a useful tool for beginning cryptanalysts.
It can be used for polyalphabetic systems such as Vigenere messages as
well as for simple substitution".
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| These units were about 8 - 10 inches long,
and came two-and-a-handbook per set. The Lawrence units were called "Secret Code Makers," and were popular in the 1930's and 1940's. (Photo courtesy Stephen A Kallis, Jr.) |
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| The entire device. (Photo courtesy Stephen A Kallis, Jr.) |