What is it? Set 345

1986 Telegraph enconder/decoder. The front pair of discs has 30 positions for the plaintext, the rear pair has 30 positions for the cyphertext, and there are 30 ways to align the front pair with the rear pair. This would be used to encode commercial telegrams.

It may be a lettering style common with Leroy sets, but zooming in the ends of the strokes (e.g. the tops of the 'U' or the right ends of the 'E') do not have the rounded ends provided by the pens used in the Leroy sets -- which suggests that Leroy sets copied an earlier font to the best of the ability of the pens.

Agreed -- other than I am not sure that it is Telegraph related. Given that this was "No. 32" it suggests that there were other discs in a full set, which would make the number of possible mappings between plaintext and cyphertext much greater than your numbers would suggest. (Of course the "No. 32" could be for keeping track of all of the devices, so they could tell whether one was lost, and if so, whose. :-)

It is interesting, however, that the letters are all printed in a single orientation instead of all with their bottoms to the center, which would mean the as they are, they would be preferentially used in the shown relationship for the top pair of discs. You would have to keep rotating it to bring the letter involved upright at other settings.

Enjoy, DoN.

Let me guess... This is a slightly more complicated version of the device you reference, with a fail-safe mode. With the battery dead, or any wire broken, the needle is in the 'Blocked' position. This is the state of the device in the picture. When operative, enough current flows to produce an 'On Line' indication. A lot more current flow produces the 'Clear' indication.