gauge (v.) Look up gauge at Dictionary.com
"ascertain by exact measurements," mid-15c., from Anglo-French gauge (mid-14c.), from Old North French gauger (Old French jauger), from gauge "gauging rod," perhaps from Frankish *galgo "rod, pole for measuring" or another Germanic source (compare Old Norse gelgja "pole, perch," Old High German galgo; see gallows). Related: Gauged; gauging. The figurative use is from 1580s. "The spelling variants gauge and gage have existed since the first recorded uses in Middle English, though in American English gage is found exclusively in technical uses" [Barnhart].
gauge (n.) Look up gauge at Dictionary.com
"fixed standard of measure," early 15c. (surname Gageman is early 14c.), from Old North French gauge "gauging rod" (see gauge (v.)). Meaning "instrument for measuring" is from 1680s.