I would like to thank Michael Marleau for his research and resulting 
article in the latest Mark Twain Journal.  He fills what I have always 
felt was a gap in Sam's riverboat history.  It had seemed strange to me 
that, considering Sam's adventurous spirit, he didn't explore the 
Missouri River when Bixby decided to learn it.  He may not have wanted 
to "learn it" but I would be surprised if he did not want to see it. 
Life on the Mississippi leaves one with the feeling that most of Sam's 
training to be a pilot was under the tutelage of Horace Bixby, when in 
fact only his introduction to steering and his final graduation to 
piloting were with Bixby. Starting with the John J. Roe, Sam's boats 
each had different pilots that Sam would steer for.

I've edited my page on the D.A. January to reflect this new research.