Macadam Hammer...... AKA ...... Knapping Hammer

I found this hammer in the flea market at an auto show. It is known by the inventor's name, a Scottish Engineer by the name of John McAdam (circa early 1800's).
It was used to lay cobblestone streets by breaking uneven edges of street paving stones and to pack the stones tightly into paving called macadam.
The donut shaped wrought iron head is 2 1/2" in diameter and 1" thick. The hammer weighs about 1 1/2 lbs.
Every macadam hammer that I have seen has the same springy shaped handle, possibly to give the hammer strikes an a little more effort, like a engraving chaser hammer does.
They do sometimes have a donut shapes head with a conical edge around the circumference.