THE STUDY OF TROPICAL SUNLIGHT. 17 



by side, on the same day, after fifteen minutes' exposure was 

 as follows: American, 35°. 6 and 34°.0 on the arm and cheek; 

 Filipino, 34 .8 and 33°.9; the difference being -0°.8 and -OM 

 in favor of the Filipino. In another series of experiments, 

 there were compared a Spanish-Eurasian and a Filipino with 

 dark brown skin. After one-half hour in the sun, the records 

 were as follows: Spanish, 37''. 1, 36°. 5, and 35°. for the arm, 

 face, and the back of the neck; whereas for the Filipino they 

 were 36°.3, 36°.3, and 34°.6, differences of -0°.8, ~0°.2, and 

 — 0'.4 in favor of the latter; and in a second series, after ten 

 minutes, 36°.2, 35°.2, and 35°.4 as against 36°.2, 34M, and 

 34°.8; differences of -0^0, -l°.l, and -0°.6. These differences 

 are but slight as between the white and dark skin, the major- 

 ity of observations being somewhat in favor of a lower skin 

 temperature for the Filipino, but after fifteen minutes both the 

 American and Spanish-Eurasian were sweating slightly, whereas 

 this was not apparent with the Filipinos. Another series of re- 

 sults was obtained after longer exposures, when all of the sub- 

 jects were sweating freely and only slight differences were ob- 

 served, thus the Spanish-Eurasian after forty-five minutes in 

 the sun, having performed muscular work, showed tempera- 

 tures of 33°.2, 33^0, and 33°.2 as against 33°.4, 32°.6, and 

 32°.8, differences of — 0°.2, — 0°.4, and — 0°.4. At rest, lying on 

 a cot, after one hour's exposure, the skin temperatures were 

 34^6, 35°.2, and 35°.0 as against 34°.8, 34°.8, and 34°.4; dif- 

 ferences of +0°.2, — 0°.4, and — 0°.6. It will be seen that the 

 skin temperatures, at rest, do not fall as rapidly as when the 

 subject is doing muscular exercise, but yet, after one hour, 

 they are from 0° to 1°.6 lower than the earlier maximum, except 

 in one observation, when the rise was 0°.7. The fifty minutes 

 of exposure, therefore, have caused no practical rise over the 

 temperatures after the first ten minutes, and indeed a lowering 

 in all but one instance, the excessive heat received by radiation 

 being taken care of by the usual means and by evaporation 

 through perspiration, whereas in the case of the monkeys there 

 was a steady rise up to the lethal point. In a final series of 

 experiments, an American and a Filipino were exposed side by 

 side for thirty minutes. In this case the final temperatures 

 were as follows: American, 36°.9, 36°. 3, and 36°. 5 as against 

 36°. 1, 35°.4, and 35°.4 for the Filipino, differences of — 0°.8, 

 — 0°.9, and — l°.l in favor of the dark-skinned man. Therefore, 

 out of 14 observations, 12 showed a lower skin temperature 

 for the Malay race, so that the series results slightly in favor 



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