The reason why I’m asking is quite an exciting one: This bookplate belonged to the man some scholars believe to be S.W. Erdnase: Edward Gallaway. In his library, a copy of The Expert at the Card Table was found, with this very bookplate inside. Gallaway owned other books on gambling, maybe also on magic. Each bookplate found can help in identifying Erdnase. So if you have ever seen this bookplate before in a book or two, or have some old libraries of magic and gambling books (most likely from the 1850s to the 1920s) to haunt, please give it a try and give a shout to Chris Wasshuber over at Lybrary, the main researcher who favors Gallaway as the man who was Erdnase!