Technique for making coins since the 8th century B.C., superseded in the 17th and 18th centuries by the screw press. A coiner or moneyer held the upper die atop the blank which rested on the lower die, while a workman (originally a slave) struck the upper die's flat end with a sledgehammer. If the first blow did not bring up the design clearly enough, a second or third blow might be necessary. The method was fast but hazardous to the coiner's fingers.
Source: Breen Encyclopedia