LE SPHINX was a pocket cryptographic device, developed around 1930 by Société des Codes Télégraphiques Georges Lugagne in Paris (France). The device consists of 10 sliding bars with two scrambled alphabets each, and should therefore be classed as an alphabet transposition cipher. At the time, it was advertised as a method for secret writing when sending (radio) telegrams.

Albert Gentet of Paris received U.S. Patent 1956384 for the device on 24 April 1934. An image of the device, formerly posted to the United States Patent Office web page, describes it as a "Pocket Cryptographic Apparatus". The patent application was dated December 1, 1931.  It is not known what brand name the unit was sold under.

The device is made up of 20 alphabet slides that the operator can scramble in any set of 10 pairs. One end is clear text and the other is the encrypted text. In the aluminum Sphinx, the pairs lock together at the ends.  In the wood version, they just push against one another.

The "white" device which resembles a double-cursor slide rule is believed to be an early version of the Sphinx. It has no gears or rack and the material is ivory on boxwood type of construction but it does have Lugagne's name attached to it. Both devices work the same way; the 20 rules can be scrambled and interchanged at will although the alphabets are not identical on the two devices.

This example of the Sphinx is owned by Robert E. Welsh. It is the earlier version made from wood and ivory. This earlier version is called ‘Transpositeur’. Le Sphinx was released in 1930 and the earlier version (Transpositeur) in 1912. (All photos in this table by Robert Welsh)

This Sphinx, less the carrying case, was up for auction on E-bay. Here is the copy provided by the seller. "Type Saint-Cyr made by the “SOCIETY DES CODES TELEGRAPHICQUES GEORGE LUGAGNE” PARIS, MARSELLA (George Lugagne Telegraphic Codes Company, Paris & Marseille, France). This machine was made in 1930 [1]. This Slide-Cipher have the “tableau” and the “strips” made of an metallic alloy  with 10 rules (Actually each one composed by two rules, numbered from the 1st. to the 20th.) with the 26 letters of the alphabet. The machine operator was supposed to arrange the rules in the order he wants (random), and then encode his message, the recipient will have the combination of the rules, in that way he can read the transmitted message. it has 10 tumble wheels to arrange the rules in any possible combination.

Slides in stowed position. (E-bay photo)	Slides in "operating" position. (E-bay photo)

Rear view and partial underside of unit. (E-bay photo)

Front view and partial underside of unit. (E-bay photo)

Derived from the original patent application, this is a detailed view of slider #15 in the apparatus. (The entire drawing was submitted by Gerry E. Sulger-Buel)

FOOTNOTES:

[1] It's likely that the aluminum Sphinx dates about 1930 or so and the boxwood model was likely to have been made some years earlier.

Contributors:
1) Robert E. Welsh <welsh@www-hep.physics.wm.edu>
2)  Gerry E. Sulger-Buel Switzerland. <gsb(at)hispeed.ch >

Dec 17/1817