The famous escapologist is being securely manacled before jumping into the water, in which he releases himself.
via Flickr http://flic.kr/p/vmjNcd
From Flickr: “Houdini being manacled. From “Maskelyne’s Book of Magic” by Jasper Maskelyne. David McKay Co., (1937). 1st American ed.” by lhboudreau