One thing this image immediately reveals is that the photo was not taken moments before Houdini made his leap into the river, as one might suppose. It was taken either before or after the stunt as Houdini (and Bess) are not even on the actual bridge from where the jump was made. No doubt having the bridge in the background made for a better photo op.
Below is a shot of Houdini's jump from the bridge itself.
|Color of Houdini's bathing suit.|
Houdini's leap from the Harvard Bridge is one of his more well-known bridge jumps, not only because of the excellent photos taken that day, but there is also a plaque commemorating the escape placed on the Boston side of the bridge by the Boston chapter of the Society of American Magicians in 1994.
Unfortunately, this plaque incorrectly dates the escape as May 1, 1908. The escape actually took place on April 30. But at the time the plaque was made, Milbourne Christopher's Houdini The Untold Story was still the most authoritative biography on Houdini, at that book misdates it as May 1 (the date on which most papers reported the event). The first book I found to contain the correct date is 2010's Houdini Art and Magic by Brooke Rapaport.
Plaque photo from The Cambridge Historical Society.