A Hoax?

The photograph shows a horse tied to a lever on the Mission bridge in 1907. Allegedly the horse was used to open and close the bridge as for instance described as follows: 

The swing span opened and closed by horsepower, and the horse's name was "Charlie." The animal was harnessed to the mechanism in the centre of the swing span and walked around in circles, opening or closing the bridge as required. Charlie was stabled in a shed attached to the side of the swing span in winter and in a field on the south bank of the river in summer. Whenever a sternwheeler whistled, Charlie went to work. 

This quote is from Postcards from the Past: Edwardian Images of Greater Vancouver etc. The authors did not show this picture. It is evident that there was no space for a horse to walk around in circles. The story is repeated by other authors but, frankly, I think it was a well-staged hoax.