On Wed, 23 Jan 2019, Greg Newby wrote:
For Project Gutenberg to determine this is in the public domain in the US (via https://copy.pglaf.org) we would want title page and verso, and also some sort of assurance that the scanned book matches the 1923 print edition. For example, we would leave out modern artwork, index, footnotes, intro, etc. if the rest is in the public domain.
The title page and verso are available in the excerpt that Google Books shows. They show copyright in 1923. The publisher seems to be one that reprints a lot of public domain works, far too many to add original content to each one. I doubt there is any new material except the cover, although since Google Books won't show all the pages it's impossible to tell for sure. There's also an oddity: When I go to the publisher's web site and look for works by Maurice LeBlanc, I see a bunch of other books, but all from prior to 1923. This particular book is missing from the publisher's site, even though it obviously did come from that publisher (having a similar style cover). My guess is that the publisher at some point reprinted the book in the belief that it was public domain, then realized that it wasn't, and took the book off their site. Now that we are in 2019, it's public domain for real.