The drinker’s thermometer measures the temperature - the degree, the intensity - of your drunkenness. In the old and ancient Republic of Greece it was thus known:
For sensible men, only three kraters: One for health, which they drink first; the second for love and pleasure, and the third for sleep. After the third one is drained, wise men go home to lie down.
The fourth belongs to bad behavior; the fifth is for shouting; the sixth is for rudeness, jest and insults; the seventh is for fights and produces black eyes; the eighth is for breaking furniture; the ninth for depression and bile; the tenth is for madness/mania and unconsciousness. It is this one that causes stumbling and collapse.
In consideration of villagers who would like to regulate or quit drinking.