ATD 97-118
Page 99
Hamilton had experienced at Brougham Bridge
William Rowan Hamilton (1805-1865)was an Irish mathematician, physicist, and astronomer who made important contributions to the development of optics, dynamics, and algebra. His discovery of quaternions is perhaps his best known investigation.
The discovery of quaternions reportedly occurred during a walk with his wife by the Royal Canal in Dublin. Upon having the inspiration for the formula, he promptly carved it into the bricks on the side of the canal. Wikipedia entry
Page 109
blindness at the heart of a diamond
This enigmatic imagery is reflected (no pun intended) in a few references:
"where the light came down sifted through so many emerald screens that it was as flawless as the heart of a diamond. " (Anne of Green Gables, Chapt. 15, by Lucy Maud Montgomery)
"It was a singularly sharp night, and clear as the heart of a diamond." A Story that is Untrue by Ambrose Bierce
Page 117
my harmless little intraterrestrial scherzo
Once again, the unseen narrator appears. By inference, the narrator is also the author of the various Chums of Chance... books referenced in ATD.