In my view Twain is drawing on Dante's "Inferno" in these last chapters to
a vision of Hell.  There's no indication that he had read D's poem that I
know of,
but he did own a detailed prose synopsis (see Gribben).  "The Inferno"
contains a
detailed description of a sand belt that exists near the very pit of hell
and bears
some similarity to the one created by Twain.  MT was always interested in
Satan as a
master of technological wizardry as well as a bringer of forbidden truths
THE MYSTERIOUS STRANGER).  If Hank Morgan is a type of Satan, his last stand
the book might well be construed as occuring on Satan's own ground.  Pay
lar attention to the concentric structure of the Yankee's
fortifications--not far
removed from the descending rings of Hell in D.

Yours,  Bob Champ