Hi,

     1)  "Mark Twain" basically means "safe water" since it indicates
two marks or twelve feet.  Right so far?

     2)  Another Mississippi riverboat pilot (or was it a captain?)
had used that name earlier, and Clemens knowingly appropriated it.
Correct?

     3)  And did I not read, in the last year or two, a second and
different explanation of the source of the name?  What was that?

     Thanks!

                                  Frank Henninger