Open AccessV. The measurement of the rate of heat-loss at body temperature by convection, radiation, and evaporation
Author(s) -
Leonard Hill,
O. W. Griffith,
Martin Flack
Publication year - 1916
Publication title -
philosophical transactions of the royal society of london. series b, containing papers of a biological character
Language(s) - English
Resource type - Journals
eISSN - 2053-9266
pISSN - 0264-3960
DOI - 10.1098/rstb.1916.0005
Subject(s) - anemometer , thermocouple , evaporation , thermometer , convection , lapse rate , atmospheric sciences , wind speed , atmospheric pressure , mechanics , meteorology , apparent temperature , radiation , environmental science , thermodynamics , chemistry , relative humidity , materials science , optics , physics , composite material
The purpose of the research detailed in the following pages has been:— (1) To investigate rate of cooling of (1) a dry and (2) a wet surface at body temperature under varying atmospheric conditions, using the kata-thermo-meter—an instrument contrived by one of us (L. H.) for this purpose; (2) To calibrate this instrument so that the rate of cooling can be expressed in millicalories per second at body temperature; (3) To separate and measure the cooling produced in still air by (a ) convection, (b ) radiation, (c ) evaporation; (4) To measure the cooling effect of wind of varying known velocity, and to calibrate the kata-thermometer as an anemometer—an observation of value since this instrument is sensitive not only to a uni-directional stream, but to every eddy, such as cannot be estimated by any vane anemometer; (5) To measure the effect on the rate of cooling of variations in the barometric pressure; (6) To deduce from the readings of the wet and dry kata-thermometer, taken in still air, the rate of evaporation from a wet surface at body temperature, and to establish the relation of this rate of evaporation to (a ) vapour pressure, (b ) barometric pressure, and (c ) temperature of the atmosphere; (7) To determine how this rate of evaporation is affected by wind of varying known velocity; (8) By these means to arrive at a method of measuring the relative rates of heat-loss to which the skin is exposed by convection, radiation and evaporation, under varying atmospheric conditions. For purposes of controlling the heating and ventilation of rooms the thermometer has been used and has acquired an authority which it does not deserve. The dry bulb thermometer indicates the average temperature of the piece of wood to which it is attached, influenced, as it is, by the temperature of all the objects around it and the atmosphere in which it is suspended. It affords no measure of the rate of cooling of the human body, and is, therefore, a very indifferent instrument for indicating atmospheric conditions which are comfortable and healthy to man.