Tapper

noun

1. One that taps.
2. One who or that which operates a screw-cutting tap for threading holes.
3. A hammer for striking a bell or chime.
4. A device for restoring a coherer to its normal resistance, after this has been affected by electric oscillations, by means of a series of slight mechanical shocks.
5. One who taps or draws liquor; a tapster; specifically, an innkeeper.