\Wa"ter ther*mom"e*ter\ (Physics)
A thermometer filled with water instead of mercury, for
ascertaining the precise temperature at which water attains
its maximum density. This is about 39[deg] Fahr., or 4[deg]
Centigrade; and from that point down to 32[deg] Fahr., or
0[deg] Centigrade, or the freezing point, it expands.