The server on which the files of the Badminton Library are stored is located in The Netherlands. As such, governing law is the law of the European Union. Additionaly, Dutch law (Auteurswet 1912) is applicable.
These laws specify that 70 years after an author's death, his or her work becomes public domain. Additionaly, there is a specification of the "shorter term" which states that if copyright has expired in another country, this copyright is not extended. In this context, works published in the U.S.A before 1923 are in the public domain , as U.S. law states that copyright expired on any work published before 1923.
It has not been verified what the date of death of every author was. As the bokks were published over 100 years ago, it is very likely that this is the case. Should that not be the case, please contact the maintainer.