[pRoc. Roy. Soc. Victoria 29 (N.S.), Part II., 1916J. 

 Ai;T. IX. — The Wet-Bulh and Kata Thermometers. 



By W. a. OSBORNE, M.B., D.Sc. 



(Professor of Physiology iu Melbourne University). 



[Read 22nd September, 1916.] 



The ordinary thermometer which records the temperature of its 

 immediate environment, is, as is now well known, an unreliable 

 guide to those air conditions that influence the animal body. " 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."l Of the three 

 air factors for which the body has to make adjustments in order to 

 keep thermostatic — namely, the temperature, water content and 

 velocity, the thermometer records one only. The great superiority 

 of the wet-bulb reading over the dry-bulb reading consists in this 

 that the wet-bulb does respond to all these three variables. Though 

 Harrington pointed out the importance of wet-bulb records, naming 

 their indications " sensible temperatures," and actually mapped 

 out the United States of America in wet-bulb isotherms for the 

 month of July ,2 yet it is to Haldane^ that we are chiefly indebted 

 for pointing out the importance of this instrument. Haldane made 

 some interesting recommendations concerning wet-bulb standards 

 of temperature in mines and factories. He also pointed out that 

 there is for the human being a critical wet-bulb temperature where 

 the conditions are such that the body, even at rest, cannot lose its 

 heat quick enough, and cumulative fever results. This has been 

 confirmed by other investigators, and I may add that I have had 

 opportunity to put the matter to the test with results that agree 

 with Haldane's conclusions. The first great extension of the use 

 of the wet-bulb in climatology occurred here in Australia when the 

 Commonwealth Bureau of Meteorology, under Mr. H. A. Hunt, pub- 

 lished maps giving wet-bulb isotherms in Australia for each month 

 of the year 1910. After this a systematised series of wet-bulb ob- 

 servations was undertaken giving records of temperature in homes, 

 offices, etc., as well as outside shade in Northern Territory, and the 

 tropical parts of Queensland. I have had access to these records 



1 Leonard Hill, O. W. Griffith and Martin Flack, The Measurement of the Rate of Heat Loss, 

 etc. Phil. Trans. B , vol. 207, p. 1S4. 



2 Quoted in Hann's Handbuch der IvlimatoloRie, 1908, vol. i., p. 57. 



3 J. S. Haldane. Journal of Hygiene, 1905, vol. f), p. 494. 



