Percival Lowell only postulated that a "planet X" might exist. Tombaugh
actually discovered Pluto in 1930. At the time Twain wrote the piece it was
not certain that the planet really existed, which explains the tone of his
writing and also explains why he expressed hope it might eventually be named
after him when it was proven.

It must have perturbated the folks on Pluto to have their planet named after
a Disney character, but at least it wasn't named Goofy. And thank God Uranus
was already taken.

Lowell also predicted that life would be found on Mars...

Kevin Mac Donnell
Austin TX