For a distance above New Orleans Mr. Bixby had volunteered information about the river, naming the points and crossings, in what seemed a casual way, all through his watch of four hours.  Their next watch began in the middle of the night, and Mark Twain tells how surprised and disgusted he was to learn that pilots must get up in the night to run their boats, and his amazement to find Mr. Bixby plunging into the blackness ahead as if it had been daylight.  Very likely this is mainly fiction, but hardly the following: 

   Presently he turned to me and said:  “What’s the name of the first
   point above New Orleans?”

   I was gratified to be able to answer promptly, and I did.  I said I
   didn’t know.

   “Don’t know!”

   His manner jolted me.  I was down at the foot again, in a moment. 
   But I had to say just what I had said before.

   “Well, you’re a smart one,” said Mr. Bixby.  “What’s the name of the
   next point?”

   Once more I didn’t know.

   “Well, this beats anything!  Tell me the name of any point or place
   I told you.”

   I studied awhile and decided that I couldn’t.

   “Look here!  What do you start from, above Twelve Mile Point, to
   cross over?”

   “I—­I—­don’t know.”

   “‘You—­you don’t know,"’ mimicking my drawling manner of speech. 
   “What do you know?”

   “I—­I—­Nothing, for certain.”

   Bixby was a small, nervous man, hot and quick-firing.  He went off
   now, and said a number of severe things.  Then: 

   “Look here, what do you suppose I told you the names of those points
   for?”

   I tremblingly considered a moment—­then the devil of temptation
   provoked me to say:  “Well—­to—­to—­be entertaining, I thought.”

This was a red flag to the bull.  He raged and stormed so (he was crossing the river at the time) that I judged it made him blind, because he ran over the steering-oar of a trading-scow.  Of course the traders sent up a volley of red-hot profanity.  Never was a man so grateful as Mr. Bixby was, because he was brimful, and here were subjects who would talk back.  He threw open a window, thrust his head out, and such an irruption followed as I had never heard before . . . .  When he closed the window he was empty.  Presently he said to me, in the gentlest way: 

“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 A-B-C.”

The little memorandum-book which Sam Clemens bought, probably at the next daylight landing, still exists—­the same that he says “fairly bristled with the names of towns, points, bars, islands, bends, reaches, etc.”; but it made his heart ache to think he had only half the river set down, for, as the watches were four hours off and four hours on, there were the long gaps where he had slept.