STUDY OF THE EFFECT OF TROPICAL SUNLIGHT. 95 



away from the spot the temperature of which was desired; and, so soon 

 as the maximum deviation of the ^'alvanometer was reached, the thermo- 

 couple was very ([uickly moved a centimeter or two nearer the desired 

 spot and when the galvanometer was apain at rest, the operation was 

 repeated until no fluctuation was noted on moving the couple. Care must 

 be observed to avoid throwing shadows upon the spot finally to be meas- 

 ured. It is clear that in proceeding: by this method the thermocouple is 

 heated e.xactly to the skin temperature. The contact with the skin at the 

 final point of measurement will be only of two or three seconds' duration. 



The .series of measurements recorded in Table II, while j^ivinj^ fairly 

 accurate comparisons, are not the true temperatures. I believe the results 

 in Tables I and II to be too low for the reason that the above described 

 technique was not adopted until later. Measurements recorded in Tables 

 III and IV are far more accurate. The higher skin temperatures which 

 I obtained in Bajruio over those obtained by Aron in Manila may be 

 accounted for, to some extent, by the difference in the method of measure- 

 ment. 



Aron records data obtained by exposing? 9 subjects: '.i Americans, 5 

 Filipinos, and 1 mestizo, to the sun's rays. His statement:' "In the sun, 

 the white skin is always slightly hotter than the brown * * *" is 

 entirely borne out neither by the data he records in Table VIII nor by 

 my experimental work in Baguio, but on the whole, except in a few 

 instances, his measurements showed higher temperatures for the white 

 skin than the brown. In the first part of his table on page 124, data 

 obtained on January 9, 1911, two cases are shown where the temperature 

 of the forehead and arm are higher for the brown skin than for the white, 

 and in the second part, data obtained on January 17, 1911, the temperatures 

 of the brown skin on the arm are recorded as equal to or higher than 

 those of the white. These records were obtained from 2 subjects, Gz. 

 a Spanish mestizo with white skin and dark brown hair, and Cs. a 

 Filipino with dark skin and black hair. 



In the continuation of the same table, on page 125, the compai'ative 

 measurements recorded for B. American, brown hair, and Or. Filipino, 

 dense black hair, show considerably lower temperatures for the American 

 on the arm, cheek, and forehead up to about twenty-five minutes' e.xposure 

 to the sun; the final measurements recorded after thirty-five minutes 

 show higher temperatures for the American. The final higher tem- 

 perature, I believe, can be explained on perfectly rational grounds to be 

 brought out later. 



Aron's statements on page 127: "The results obtained so far indicate 

 that the temperature of the human skin increases in the sun, but does 

 not reach the normal body temperature,'' and on page 129: "An increase, 

 even to the normal body temperature is prevented by evaporation of 

 sweat" are not in accord with the results I obtained in Baguio. 



I continually observed skin temperatures l"" to 1"\5 higher 

 than Aron's maxima and 2° higher than blood temperature. The 



' Loc. cit., 125. 



