Sling psychrometer and Carry Case
c. 1950A hand held swivel thermometer tool with two glass thermometers in a wooden frame and a black bake lite handle. At the bottom of the wooden frame is a black plastic shield with a screw which can be unscrewed. It has a brown hard leather carry case.
It was used to gauge the weather to determine if the area was a fire hazard zone. It was used by volunteers of the Bush Fire Brigade. It is known as a sling psychrometer, which has a dry thermometer and a wet thermometer. The dry thermometer measures the current ambient air temperature, whilst the wet bulb has a saturated cotton sleeve. When the bottom plastic knob is unscrewed, the end is then filled with water which then saturates the cotton sleeve. When you swing or "sling" the device rapidly through the air for about a minute, the airflow accelerates evaporation from the wet cloth sleeve. This evaporation cools the wet bulb. By comparing the temperature drop on the wet bulb against the dry bulb, you can use a companion psychrometric chart or slide rule to determine exact relative humidity and dew points.
Details
Details
Copyright and Reference
Copyright and Reference
Courtesy of Katanning Historical Society.
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