from The Century Dictionary and Cyclopedia
- n. In pianoforte-making, a lever mechanism intermediate between the jack and the hammer proper.
Sorry, no etymologies found.
The first action gave the blow with more direct force than the second, which had the notch upon what is called the underhammer, but was defective in the absence of any means to regulate the distance of the "go-off," or
Another of his guns, Humpal said, was a rare harmonic rifle, one of the first repeating reflex rifles, also called underhammer rifles, made in Windsor by Nicanor Kindall (who reportedly paid inmate labor 32 cents a day to make the guns) in the 1800s.