Hi Aaron,A very good question. Thanks to the Clinton administration extending copyright to what most would consider a ridiculous extent about a year and a half ago, a lot of what was considered public domain from the late 19th & early 20th c. has fallen into the protected catagory.
He may well be dealing with the new laws (covering material 75 yrs past the authors death, I believe - looks like anything written by Sam Clemens just squeaks into the public domain ! Think about it, until 1997 with the new law - if I interpret it correctly, Huck Finn & Tom Sawyers exploits - written well over 120 years ago, and in the public domain for over 50 years would suddenly be protected material).
As a result he would need permission from the authors estate to put the book back into print. He may well need permission from the original publisher - he may have neither. I will have to jump through similar hoops when I get Maj. Brustem's book on the Burgundian army translated - assuming I can find anybody who wants to publish a translation.
The complexities of modern life.... 
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Bob R.