Sounds like the Chronophage clock in Cambridge: https://en.wikipedia.org/wiki/Corpus_Clock https://en.wikipedia.org/wiki/Corpus_Clock. It it's purely mechanical

Sounds like the Chronophage clock in Cambridge: https://en.wikipedia.org/wiki/Corpus_Clock https://en.wikipedia.org/wiki/Corpus_Clock. It it's purely mechanical but has odd pauses in the ticks etc