The Collaborative International Dictionary of English v.0.48:

Gauger \Gau"ger\, n.
   One who gauges; an officer whose business it is to ascertain
   the contents of casks.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

GAUGER. An officer appointed to examine all tuns, pipes, hogsheads, barrels,
and tierces of wine, oil, and other liquids, and to give them a mark of
allowance, as containing lawful measure.