Selfmate in 40 by Petroff

[Alexander George]

In a recent article on chess.com, you can find a selfmate in 40 by Alexander Petroff, the great Russian player. It's dedicated to Paul Morphy and the pieces form the letter "M" (sort of). Anyone know if it's sound? (And does anyone know anything about Morphy's reaction?) The problem appears below, but I urge you to read the article as it contains much interesting information about, and recollections of, Petroff.

Alexander Petroff, s≠40, dedicated to Paul Morphy

[Added later: I see that Gary Kevin Ware has also mentioned this problem in his Gary's Gems.]