12 Fowler, Chemical Action of Tropical Sunlight. 



isolated record made by the author last September at 

 York Place gave 18, appreciably higher than Dr. Bailey's 

 maximum, but such a result is evidently exceptional. 

 These great differences in the amount of actinic light 

 must, one would think, correspondingly affect the human 

 organism. One of the most depressing features of life in 

 Manchester and other large towns is the absence of light. 



One result from Pontresina is actually higher than 

 any obtained in Calcutta, Dr. Bailey suggests that the 

 high results here may be due to the high temperature, but 

 the highest shade temperature he gives for Pontresina 

 is 86° Fahr., while in April in Calcutta it was seldom 

 below 98° Fahr. and often over 100°. Moreover it has 

 already been shown that the effect is practically in- 

 dependent of temperature. It is quite likely, however, as 

 Dr. Bailey also suggests, that the great height of the 

 station, viz., lo.oco feet, will be of influence, owing to the 

 diminished atmospheric absorption. In fact the two 

 results, taken respectively at 6,000 and 10,000 feet, would 

 bear this out. 



Possible Relation betweeii Photo-chemical Activity and 

 Sufistroke. 



It has been held that the sunstroke effect is due to 

 the actinic rays, and it is stated by Colonel Maude* that 

 by protecting the head and neck with a red screen, on 

 the analogy of the photographer's red lamp, he has been 

 able completely to withstand the effect of sun, even in 

 the hottest parts of India. 



The Pontresina results are specially interesting in 

 reference to the possible relation between the chemical 

 intensity of the light and its power to cause sunstroke. 

 It is universally considered unsafe to be out in the sun 

 during the day in India, without a properly constructed 

 * " War and the World's Life," p. 364. 



