Original ball & chain

[Spencer]

Edit: in fact identical to Tower handcuff mechanism.
http://www.handcuffs.org/tower/

There is some probability that the one in the previous link is bits cobbled together, and not original?

Thanks for the photo...I am very familiar with that one and it represents one of the better jobs of "cobbling" that I've seen but it is NOT a factory job. By going to Handcuffs.org you can see what the real thing looks like.