It was published in 1924 so I think it's still under copyright in the US. According to Project Gutenberg, "Works published and copyrighted 1923-1977 retain copyright for 95 years. No such works will enter the public domain until 2019 unless one of the other rules applies."
Here's an inkmesh sort of options where to purchase the book.
http://www.inkmesh.com/ebooks/a-pass...ssage+to+india