2. A device consisting of two thermometers, one a dry bulb and the other a wet bulb.
Both are heated to 110°F (43.3°C) and the time required for each thermometer to fall from 100° to 90°F (37.8° to 32.2°C) is noted. The dry bulb gives the cooling power by radiation and convection, the wet bulb by radiation, convection, and evaporation.
From this, the temperature as it affects the body can be deduced; or it is a measure of the heat content of the environment that takes into account air movement as well as temperature.
The bulb may be silvered to minimize radiation effects or blackened to maximize them.