Probably a 1830-1875 M&H Armitage MouseHole weighing 2.1.2 . Nearly ruptured myself picking it up from the trunk of my kid's Mustang, thought it was a 100lb'er. The trunk lift over height kept rising as the suspension unloaded while the anvil was raised.
There is a I N stamped between the feet , under the horn. Sorry I did not have the dirt brushed off prior to taking the images, not knowing they were there. Any idea what it could indicate. There is some Roman number reference to either 1 or 1000 and 90 ?