TEMPERATURE AND HUMIDITY 



71 



proximity of the skin, and possibly of the nasal cavity, and therefore in warm 

 air this difference frequently does not exist. In India Crombie found in 

 fifteen carefully taken observations that the mouth temperature was 0'22° F. 

 below that of the rectum, whereas Pembrey found it as much as 4-5° F. — 

 i.e., 2*5° C. — ^below that of the rectum in cold weather in England. It is 

 possible, therefore, that it is a better site for thermometric observations in the 

 tropics than in Europe. 



Rectal temperatures under ordinary conditions give the highest readings 

 and are the truest indicators of the internal temperature of the body; but this 

 is not a method open to clinical use, except in children and instates of coma. 



The conclusion is that if care be taken that neither hot nor cold articles 

 have been recently placed in the mouth, and particularly if the mouth has been 

 kept closed for a short time, the temperature from the thermometer placed 

 under the tongue is, without doubt, the most accurate for ordinary clinical 

 work in the tropics, for in that position the thermometer is as completely 

 as possible protected from the influence of the nose and the skin. 



A thermometer, however quickly it reacts to its surroundings, must be left 

 a reasonable time in the mouth, by which is meant two or three minutes, so 

 that the temperature of the closed mouth may approach that of the rest of 

 the body. Crombie gives the time for the accurate recording of the tempera- 

 ture in India as : — 



Ten minutes in the well-closed and dry axilla. 



Eight minutes in the mouth. 



Three to four minutes in the rectum. 



The mean daily temperature of man for the hours 8 a.m. to 12 midnight in 

 ^ the Temperate Zone is as follows : — 



98-45° F. (36-90° C.) in the axilla. 

 98-36° F. (36-87° C.) in the mouth. 

 98-96° F. (37-20° C.) in the rectum. 



The so-called normal temperature of man in the mouth may be placed at 

 98-40° F. (36-90° C.) or 98-6° F. (37° C), and was determined as the mean 

 temperature from 8 a.m. to 12 midnight by John Davy in 1837, and by some 

 mistake it has been interpreted into the mean temperature for the twenty- 

 four hours, which is different, being probably lower. 



Crombie gives the following as the means of the observations of Ogle, 

 Allbutt, Casey, and Rattray: — 



Mean Morning 



Mean Afternoon 



Mean Twenty-four 



Maximum Daily 



Temperature. 



Temperature. 



Hours' Temperature. 



Range. 



97-763° F. 



98-341° F. 



98-084° F. 



1-41° F. 



But at present there are insufficient data upon which to base a definite 

 conclusion as to the mean temperature of human beings for the whole twenty- 

 four hours. 



The average temperature in the mouth varies from between 96° F. and 97° F. 

 to a little under 99° F., and the rectal temperature from 97-2° F. (36-28° C.) 

 between 2 to 5 a.m. to 99-4° F. (37-45° C.) between 4 to 7 p.m. 



Pembrey gives the mean daily temperature as being 98-6° F. (37° C), the 

 maximum 99-5° F. (37-5° C), and the minimum 96-8° F. (36° C.) 



Effect on Temperature. — Having now defined what we mean by a 

 normal temperature in man, it is necessary to inquire into the effects 

 of high atmospheric temperatures and varying humidity upon man. 



The experiments of Lining (1738), Ellis (1758), Blagden and Fordyce (1775)' 

 established the fact that a normal man, suitably clothed, can regulf^^e his 



