I've had this old screw jack for ages.
The patent date cast into it is June 8, 1875. This patent was granted to Lewis O'Hara of Oswego, New York. His improvement consisted of building a lever actuating a rod within the screw of the jack so that the pad could be screwed up to the bottom of the item you wanted to lift, which would be then lifted off of the ground by the action of the lever. Very clever design. It's weakness is the cast iron socket for the handle: I managed to crack this lifting something heavy. Nickle brazing made it good again. So cool to be using something designed well over a century ago. I doff my hat to you, Mr. O'Hara!