Palm to Starhemberg and Visconti, 1727

Summary. The catalogue listed two ciphertexts of Palm, the Emperor Charles VI’s resident in London, to Visconti and Starhemberg, 1727. DECODE R7927 (ff. 16–17) is a German letter fragment to Starhemberg, written mostly in clear. Fourteen passages are in a cipher that uses numbers 2–79 for letters, about two per letter, and three-figure groups for words and syllables. The Deciphering Branch glossed only a handful of the groups. R7930 (f. 41) holds only the cover of a Palm–Visconti letter and, on its verso, a codebreaker’s 1–500 grid for a French or Italian nomenclator. The letter itself is not on DECODE. The key filed between them, R7928, belongs to Windischgrätz and Starhemberg and contradicts the glosses. A solver (simulated annealing with a German 5-gram language model), with the gloss values fixed, did not converge on 162 letter tokens. The passages were not deciphered; Palm’s key or the contemporary clear copy is needed.

Add MS 32270 f. 16v: clear German lines and a ciphered line with interlinear glosses — f. 16v (DECODE R7927, image 2): the clear text “So sehen sie doch den ihrer Meinung nach bevorstehenden Krieg …”, then the first ciphered passage with the decipherer’s glosses. Image: British Library, Add MS 32270 f. 16v, via DECODE R7927 (image 2).

01 The four records

Record	Folios	What it is
R7927	ff. 16–17	Docket “Palm & Staremberg / German”. A letter fragment in German with 14 ciphered passages. Images 1 and 4 show only the other side of the leaf through the paper.
R7928	f. 18	“Count Windischgrätz & C^t Staremberg”: a letter key 1–50 with about 30 values filled in (2 b, 5 n, 8 u, 9 c, 10 i, 20 o, 40 r …).
R7929	ff. 19–40	The Emperor to Starhemberg, 42 pp., marked “Decrypted”. No images on DECODE.
R7930	f. 41	Cover “Palm to Visconti 1727 … Visconti to Palm”. On the verso is a decipherer’s tally grid, 1–500 (Addresse 21, Hollande 109, Italie 120, Traité 215, syllables in the 300s and 400s, several nulls). This is a different system, and no ciphertext is imaged.

02 The cipher of R7927

162 letter tokens across 47 values (2–79) and 23 code tokens across 10 values: 124, 138, 170 (five times), 210 (three), 230 = der (six), 380, 423, 432, 474 and 799. The glosses, in German Kurrent script, give 33 = e, 23 = n, 10 = d, 15 = t, 40 = ſ, and probably 9 = u and 4 = z. The clear text concerns how England saw the war then coming over Gibraltar and the Hanover alliance, and the rumours that a rupture would bring (“dass im Fall es zu einer Ruptur kommen solte, man …”). One passage ends in … d ſ ? e t z e n zu bringen.

03 What was tried

The R7928 key applied to the passages: it gives 40 = r and 23 = u where the glosses have ſ and n. Ruled out.
Simulated annealing on the letter values (the project’s de-modern 5-gram model), with the codes drawn from a list of German words and syllables and the clear context kept for scoring. With and without the gloss values fixed, the output was not German.
A control on synthetic German of the same shape (162 letter tokens over 47 values), with the true values of the six commonest symbols fixed, recovered only 44–50% of the tokens. At that rate the text cannot be made out, so a text of this length cannot be deciphered without the key.
A web search for a printed decipherment of Palm’s 1727 intercepts found nothing.

04 What remains

None of the fourteen passages was deciphered. With about two homophones per letter and only 162 letter tokens, a ciphertext-only attack has too little to work on. What is needed: Palm’s Imperial cipher (Vienna, HHStA, England, Berichte 1727), the Deciphering Branch’s clear copy (other Willes volumes, SP 107), or images of R7929.

05 Sources

British Library, Add MS 32270 ff. 16–18, 41: DECODE R7927, R7928, R7929, R7930 (login required).

Transcription, glosses and solver scripts: palm1727/.