In Life on the Mississippi, what does young Twain jot down in his notebook?

When it becomes clear to Mr. Bixby that Twain is not
"learning the river," he gives his cub pilot some good
advice:

My
boy, you must get a little memorandum book, and every time I tell you a thing, put it
down right away. There's only one way to be a pilot and that is to get this entire river
by heart. You have to know it just like ABC . . .
.

Twain takes Bixby's advice
and soon his notebook "fairly bristled" with information. Twain says he recorded in his
notebook "the names of towns, "points," bars, islands, bends, reaches, etc." It bothers
him tremendously that his book is incomplete since he misses much of the river every
time he sleeps.