Rudolf II’s Alchemical Handbell

Summary

Rudolf II of Habsburg (1552–1612) ran his court at Prague Castle as a centre for alchemical, astrological and occult enquiry. A small handbell made for him by Hans de Bull around 1600 — cast from electrum, an alloy of the seven planetary metals, and now in the Kunsthistorisches Museum in Vienna — shows the seven planetary deities on the outside, and carries a spiralling 163-letter Greek inscription inside the bell and a Hebrew inscription on its iron clapper. The Greek text is a cipher, and it remains unsolved. With Corinna Gannon and Sarah Lang, I investigated the inscription and what kind of cipher it could be.

Approach

Every letter of the inscription comes from the first ten letters of the Greek alphabet, so the text behaves like a cipher written in the digits 0–9. The paper corrects the first published transcription, works through the statistics — letter frequencies, repeated words, coincidence measures — and estimates the likely plaintext language (Latin ahead of Greek and German). Cipher types that postdate the bell are ruled out; the statistics point most plausibly to a polyphonic cipher, one in which a single ciphertext symbol can stand for several different plaintext letters, with a two-letters-per-symbol (digraphic) cipher not excluded. At 163 letters the ciphertext is short enough that, as the paper notes, a unique solution may not even be provable.

Publications and media

Bean, R., Gannon, C. and Lang, S. (2023). The cipher of Emperor Rudolf II’s ‘Alchemical Handbell’. In Proceedings of HistoCrypt 2023.

Conference talk: HistoCrypt 2023, Munich.

See also the full publications list and the presentations archive.