In 1818 the compositor, evidently reading this as one in a series of journal entries,
surmised that it could not follow "September 12th" and added an integer to make it
"September 19th." But, of course, what the text intends us to understand by its idiom
is, "On September 9th the ice began to move." Since this is the date in the manuscript
and it is restored in 1831, the text has been emended here.