from The Century Dictionary.
- noun A machine-hammer in which the blow is partly or wholly made by a spring to which tension has been imparted by mechanism during the lift of the hammer-head.
Sorry, no etymologies found.
Down this intestine, their points sticking through the slot, moved the tacks in single file to a spring-hammer close to the floor.
The spring-hammer drew back, a little trap or mouth at the end of the slotted tin barrel opened for the tack, the tack jumped out, turned over, landed point downward upon the right spot in the carpet, the crouching hammer sprang, and --