Skin in the Dark Paces of Mankind. 379 



posod, the thermometer in the sun's rays being considerably 

 above 100°, and though my face was scorched, nothing like the 

 effect described by Sir Evcrard took place. 



Sir Everard next attempted to compare the inflaming and 

 blistering power of the sun'*s rays with that of hot water. He 

 says, that water at the temperature of 120° was painful to the 

 body, and became unbearable when still further heated. From 

 this experiment and the preceding, he wishes us to infer a power 

 of vesicating in the sun's rays not in proportion to their tem- 

 perature. 



In a third experiment, he exposed the backs of his hands to 

 the sun with a thermometer on each, the one hand being un- 

 covered, while the other had a covering of black cloth under 

 which the thermometer was placed. After ten minutes, the 

 degree of heat on each was marked, and the state of the sur- 

 face examined, and this was repeated three times. During the 

 last trial, the thermometer which had its ball covered by the 

 cloth stood at 106°, while the other was at 98°. The exposed 

 hand was scorched, that covered was unaffected in all the trials. 

 ' I have not repeated this experiment because it is subject to 

 an obvious fallacy, for the ball of the thermometer being be- 

 tween the cloth and the part, a space intervened, and across 

 this space the heat from the cloth could only pass by radia- 

 tion or by transmission through the thermometer, but not di- 

 rectly from the cloth to the hand, so that the heat might not 

 accumulate on the skin. 



In a fourth experiment, a Negro bore the sun''s rays on his 

 hand when a thermometer on the part indicated 100° without 

 any scorching being the result. As the scorching of which Sir 

 Everard speaks could be only a slight blush, it might not be 

 observed on a sable skin. However, I do not question the re- 

 sult of this experiment. 



Sir Everard observed in his next experiment, during the 

 course of an eclipse, as the darkness on the sun's disk dimi- 

 nished, the scorching power of the rays, concentrated by a lens, 

 increased in a ratio which is assumed to be greater than could 

 be accounted for by the mere rise of temperature during the 

 time of the experiment. Whence it is to be inferred that the 

 excess of effect is due to the increased quantity of light pre- 



