A direct-reading mercury thermometer for the wet bulb globe temperature index

Abstract

An instrument for direct measurement of the wet bulb globe temperature index (WBGT index) is described and tested. The instrument is a fluid analogue computer based on the mercury-in-glass thermometer and has no electronics. A linear correspondence was obtained between the readings of the instrument and the WBGT index calculated by the conventional method from the readings of individual wet bulb, dry bulb, and globe thermometers. The instrument provides a simple and valid method for measuring the WBGT index.