Scott,

The 1857 dates were first proposed by Edgar Branch. More recent research by
Michael Marleau indicates the year 1859 was the most likely dates of
service on that boat in the company of Capt. William B. Miller.  See this
online article for the RUFUS J. LACKLAND.

http://www.twainquotes.com/Steamboats/LicensedPilot.html

Fears’s compilation was evidently based on Branch’s older research and not
the updated research of Marleau.

Barb