Magical Rope Ties and Escapes was originally published in the UK by Will Goldston in 1921. It was never released in the U.S. The only other reprint I'm aware of was a paperback by Houdini's Magic Shop in 2011. Of all Houdini's books, this is the one that contains the most photos of him.
You can purchase this new limited edition of Magical Rope Ties and Escapes at CollectingMagicBooks.com.
Thank you, Philip!
UPDATE: Excited to have my copy in hand. It's every bit as good as advertised. The quality of the illustrations and photos match the original exactly. (This is certainly not the case with the 2011 reprint.) Originals are scarce and expensive, so if you don't have this book or want a reading copy, this is the one to get!