• Botsball thermometer

Botsball thermometer

  • H08 - H09

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The Botsball thermometer, formely called the wet globe thermometer, combines air temperature, humidity, wind and thermal radiation into a single reading that is closely related to human responses.

The Botsball thermometer consists of a 2-3/8 in. hollow copper sphere that is painted black and covered with a double layer of black cloth. The cloth covering is continuously moistened by water seeping from the aluminium reservoir tube attached. The stem of a dial thermometer passes along the center-line of the water reservoir tube and into the globe to sense its temperature.


When the Botsball thermometer is placed in a hot area, the globe is warmed by the surrounding air and by heat radiated from hot surfaces. It is also cooled by evaporation according to the wind and humidity. After about 5 minutes, the Botsball thermometer reaches an equilibrium temperature which provides a direct physical measure of the thermal environment.


Any change in air temperature, humidity, wind or thermal radiation that causes the Botsball temperature to rise will increase human discomfort or stress. Conversely, any change in these conditions that lowers the Botsball temperature will alleviate discomfort or stress. Thus, the Botsball temperature provides an excellent index of human response to heat.

Occupational heat exposure limits have been proposed by the American Conference of Governmental Industrial Safety and Health. The US Department of Labor will issue heat exposure regulations under the provisions of the Occupational Safety and Health Act. The Botsball thermometer can be used to determine quickly which work environments may exceed these limits.

If the Botsball thermometer is to be used in magnetic fields strong enough to attract a steel tool held in the hand with notoceable force, a slight error in the indication of the dial thermometer might result. For such applications, the Botsball thermometers with magnetic shielding should be used.

The Botsball thermometer is supplied in a kit containing the wet globe assembly with attached water reservoir, an 8 ounce squeeze bottle for filling the water resevoir, a special dial thermometer inserted into the globe and operating instructions. Order by number from the following list:

HO80-00000 Botsball thermometer kit, fahrenheit scale
HO85-00000Botsball thermometer kit with magnetic shielding fahrenheit scale
HO90-00000 Botsball thermometer kit, centigrade scale