Hello, This was the find of the day on a dollar table!!!!!!  Didn't know what it was until I got home. This rusty crusty beauty  has a stamped Patent Date of July 26 1910. Patent Number 965716. Champion Dearment Farrier's Nail Driving Hammer. Regards, Lou

Neat!  Is the screw holding the head on the handle original, or a later field solution?

Hello, Bill. I believe the screw is original to the hammer. The screw holds the spring clip described in the Patent. I am still not sure I understand the function.

Here is an excerpt from the Patent Claims. Patent holder William J. Kelly states;

My invention relates to improvements in farriers nail driving hammers, my object being to provide a tool of this character which shall be adapted to automatically expel the nail point from the claw of the hammer, after the protruding portion of the nail has been twisted off by the hammer, as is customary in shoeing horses. Regards, Lou

Ah.  I hadn't noticed that flat spring.  Interesting idea.