Abstract: A housing is permanently connected to a water supply of a building and includes an evaporative water panel allowing water to flow downwardly and wick upwardly. A circulating device is provided for directing air from the building through the water panel. A reservoir is positioned in the housing for supporting the water panel and holding excess water deposited from the water panel. A water distributor is supplied for moving water from the water supply to a top of the water panel. A water control arrangement is responsive to the water level therein for automatically controlling the flow of water to the water panel to provide a desired humidity level in the building.

Abstract: Apparatus for measuring the surface tension of a liquid contained in a flow-through pressure vessel (60) includes a pair of tubes (50,51) having small and large orifices positioned below the surface of the liquid. A source (10) provides gas through a pressure regulator (15) and a flow regulator (30) to the tubes. The bubble rate from the orifices is controlled by needle valves (40,41) and is made independent of the pressure in the vessel by the flow regulator (30). Differential pressure transducer (70) measures the pressure in the tubes as an indication of surface tension. Check valves (72,73) protect the transducer, and a thermometer (65) measures liquid temperature.