The uniquely compact Bacharach Sling Psychrometer accurately determines percent relative humidity without the necessity of consulting complex tables. There is no need to wet the wick each time a reading is taken; the Sling Psychrometer contains a slide rule calculator which correlates wet and dry bulb thermometer indications for direct reading of relative humidity. When not in use, the thermometer case telescopes into the handle for protection.FEATURESThermometer, +25?F +120?F Red Spirit Filled.Designed for portability (7.5 inch long x 1 inch diameter).Slide rule construction quickly converts temperature to relative humidity.Built-in water reservoir holds sufficient water for several hours of testing.Thin bulb design gives fast thermal response.Thermometers constructed of shock-resistant glass; stems have deep-etched numerals and 1° scale divisions for easy readingAccurate to within ±5% R.H.APPLICATIONSMeasurement of comfort conditions in air conditioned environments, hospital operating rooms, storage areas and laboratories.Tests in industrial atmospheres where high or low humidity may be critical in manufacturing processes.School athletics - to determine safe conditions for practice.