While parsing through the Day By Day pages I came across a note about 
Clemens and Bixby on board the RUFUS J. LACKLAND from 11 July to 3 
August 1857, going up the Missouri River.  Fears notes mention of this 
on twainquotes ( http://www.twainquotes.com/Steamboats/CubPilot.html) .  
I'm curious about any confirmations about this and possible schedules.