Classic brass porthole hygromometer.
The hygrometer: the ship's captain or meteorologist can use these to determine changes and patterns in % relative humidity, to aid in weather forecasting and prime varnish drying weather!
Wall mount and ready to use. Heavy glass and heavy solid brass casing and hardware. This matches our 5-1/2" Porthole Clock, barometer and thermometer.
Porthole hygrometers only available in 5-1/2" size and the face measures 3-1/2".