p. 254 ‘something about a diving bell…’; the satory of Charles Spalding’s exploits is at wikipedia here;
Erasmus Darwin’s poem, The Botanic Garden Part 1 The Economy of Vegetation is here
“Shrin’d in the Deep shall Day and Spalding mourn
Each in his treacherous bell- sepulchral urn!”
p. 254-255 The events mentioned on these pages are elaborated from the descriptions in Dr Bentley’ Diary
p. 256 ‘…that absurd Geography’; Jeannie is referring here to the last work that Tytler is known to have been working on, in collaboration with the Salem bookseller Barnard Macanulty and Joseph Nancrede, a Boston bookseller. A proposal was published but the work never appeared:
Proposals for Publishing by Subscription a New System of Geography, Ancient and Modern, by J. Tytler: A New System of Geography, Ancient and Modern
By Joseph Nancrede, James Tytler, Barnard Brian Macanulty
the proposal is online here
‘…Tommy Russell’s execution’; the only letter of any length that survives in Tytler’s hand is to Thomas Russell; Russell’s own diary records their friendship during the years Tytler stayed in Dublin; they were clearly of one mind both politically and philosophically, and Tytler, being the older, seems to have had a marked influence on Russell. Russell was eventually hanged for his part in the uprisings in Ireland at the end of the century. His last words, uttered at the hanging, are said to have been ‘Is this the place?’.
p. 258-259 This passage, as with all those described as being written in purple ink, is wholly fiction, inspired only by the imagined state of mind of tytler at this time, and the mention made by Bentley that Tytler had called at the house of one Oliver the night he died, asking for a candle.