I learnt today from Barbara Becker that Wm Huggins’ observing notebook 1 and notebook 2 have been scanned and are available online at Wellesley College, USA.
It looks a super resource.
Page 37 of notebook 2 is from 1866 May 16. He notes “Received at 5 o’ck a letter from John Birmingham Tuam, Millbrook announcing new star in Corona seen by him on May 12, 1866”.
This was T CrB in eruption. Further down the page is Huggins’ sketch of its spectrum.