Check the listing for details. Wet-Dry Bulb Hygrometer, Wall Mounted Thermometers - Eisco Labs. Condition: New. Listed at 22.99 USD. Wet-Dry Bulb Hygrometer, Wall Mounted Thermometers - Eisco Labs Comprised of two identical dual-scale thermometers.Water cistern fitted to the lower case is connected to the "wet bulb", providing the contrasting "Dry" and "Wet" bulb readings.Can be used to determine the water vapor content, or relative humidity, of the air at a given temperature.Wall mounted. Measures 11.5" long, 3" wide, and 0.5" thick.Great for students and weather enthusiasts. The Mason's Hydrometer, also known as a Wet/Dry Thermometer, is comprised of two identical dual scale thermometers. One thermometer has a dry bulb, while the other bulb is kept wet via connection to a water reservoir. Relative humidity is calculated from the difference in readings of the thermometers. Dual scale ranges: -10 to 50°C; 20 to 120°F. Wall mounted. Measures 11.5" long, 3" wide, and 0.5" thick. Great for any school or home laboratory. Product Details Brand Eisco Product Type Hygrometers MPN PH0232B Check out my other items.