||"Mark 2" & Mark Twain
[from Clemens's 1857 piloting notebook]
The cub pilot Sam Clemens, learning his trade in 1857, filled his notebook with detailed technical notations about the river, written in a tiny hand. Occasionally, as shown here, he noted soundings of "mark 2," that is, "mark twain," a water depth of two fathoms. In 1863, as a young reporter in Nevada Territory, he would appropriate the term for his pseudonym.