THE SKIN A REGULATOR OF ANIMAL HEAT. 49 



and to point out the analogy subsisting between this 

 process and that of the evaporation of water from 

 a rough porous surface, so constantly resorted to in 

 the East and West Indies, and other warm countries, 

 as an efficacious means of reducing the temperature 

 of the air in rooms, and of wine and other drinks, 

 much below that of the surrounding atmosphere. 

 The quantity of fluid evaporated from the skin during 

 profuse sweat so far exceeds that given out during 

 the highest insensible perspiration, that two pounds 

 in weight have been lost by this means in a couple 

 of hours, an amount evidently sufficient to carry 

 off the largest quantity of superfluous animal heat 

 which can ever be present. In the performance of 

 this function the skin is, indeed, assisted by the ex- 

 halation from the lungs ; but as both act on the same 

 principle, the explanation is not affected by this cir- 

 cumstance. 



Bearing in mind the preceding explanation of the 

 functions of the skin, the following remarks from 

 Dr. Thomson's work* will be read with interest. 

 u Dr. Davy, in his Travels in Ceylon, states, from 

 his personal observation, that, on first landing in a 

 tropical climate, the standRrd heat of the body of a 

 European is raised two or three degrees, and febrile 

 symptoms occur, which require temperance, the 

 avoiding every cause of excitement of the vascular 

 system, and the use of aperient medicines. All au- 

 thors, and indeed every observing person who has 

 visited the torrid zone, agree that with the languor and 

 exhaustion resulting from the high temperature of 

 the atmosphere, there is a greatly increased mobility 

 of the nervous system. The action of the cutaneous 

 vessels amounts to disease, and produces that ecze- 

 tnatous or vesicular eruption of the skin, known 

 by the name of prickly heat, which occurs in Eu- 

 ropeans who visit the West Indies, on their first 



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