Samuel Clemens was not the first writer to use the name Mark Twain, which meant two fathoms, a safe depth for a riverboat. It originally belonged to an old, highly respected river pilot named Captain Sellers, who used to like to show off his knowledge just a bit too much:
The old gentleman was not of literary turn or capacity, but he used to jot down brief paragraphs of plain, practical information about the river, and sign them MARK TWAIN, and give them to the New Orleans Picayune. They related to the stage and condition of the river, and were accurate and valuable; and thus far, they contained no poison. But in speaking of the stage of the river to-day, at a given point, the captain was pretty apt to drop in a little remark about this being the first time he had seen the water so high or so low at that particular point for forty-nine years; and now and then he would mention Island so and so, and follow it, in parentheses, with some such observation as disappeared in 1807, if I remember rightly. In these antique interjections lay poison and bitterness for the other old pilots, and they used to chaff the Mark Twain paragraphs with unsparing mockery.
It so chanced that one of these paragraphs became the text for my first newspaper article. I burlesqued it broadly, very broadly, stringing my fantastics out to the extent of eight hundred or a thousand words. I was a cub at the time. I showed my performance to some pilots, and they eagerly rushed it into print in the New Orleans True Delta. It was a great pity; for it did nobody any worthy service, and it sent a pang deep into a good mans heart. There was no malice in my rubbish; but it laughed at the captain. It laughed at a man to whom such a thing was new and strange and dreadful. I did not know then, though I do now, that there is no suffering comparable with that which a private person feels when he is for the first time pilloried in print.
Captain Sellers did me the honor to profoundly detest me from that day forth. When I say he did me the honor, I am not using empty words. It was a very real honor to be in the thoughts of so great a man as Captain Sellers, and I had wit enough to appreciate it and be proud of it. It was distinction to be loved by such a man; but it was a much greater distinction to be hated by him, because he loved scores of people; but he didnt sit up nights to hate anybody but me. Mark Twain, Old Times on the Mississippi, 1875. Later reprinted in Life on the Mississippi, 1883