132 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 63 



find a site at some elevation on the hillside or in the mountain val- 

 leys beyond the reach of the morning fog and the excessive humidity 

 at the shore/ The records of the Weather Bureau show that these 

 places on the coast or within reach of the fogs which penetrate 

 inland have a greater humidity than Boston or New York, the mean 

 annual absolute humidity for Santa Barbara, Los Angeles, and San 

 Diego being given at 4.20, 4.42 and 4.34 grains, more than one-third 

 more than that of New York and Boston, 3.19 grains and 2.84 grains. 

 The mean annual relative humidity of all these places mentioned is 

 from "JT. to 73 per cent. But the advantage of places like Santa Bar- 

 bara, San Diego, Redlands, and Riverside, lies in the fact that the 

 mean annual humidity shows a remarkable variation during the 

 twenty-four hours compared with places like Boston, New York, or 

 Philadelphia, where the daily range is much less. At Redlands, fifty 

 miles inland from the Pacific Ocean, one of the best known stations, 

 the hygrometer has been known to indicate in fair weather 55 per cent 

 at 4.30 p. m., and 80 per cent at 6.00 p. m. The relative humidity 

 is sometimes as low as 30 per cent for a limited time during the 

 day, and 70 to 80 per cent at night when the temperature is from 

 44° to 60° F. 



It may as well be stated that the government records of humidity 

 are quite misleading when we use them to judge of the climate of 

 any given place. The observations are made at 8 a. m. and 8 p. m., 

 but in the invalid's day, made up of the intervening hours, the rela- 

 tive humidity reaches a much lower mark than the records show. 

 I often observe a relative humidity in Virginia of 25 or 30 per cent 

 at 2 p. m., and 95 or 98 per cent at night or in the early morning, 

 especially when dew falls after a bright, invigorating day. I think 

 that people, whether sick or well, adjust themselves to these natural 

 changes of humidity if properly clothed and constantly in the open 

 air ; but when subject to rapid changes in humidity, as in going back 

 and forth from the excessively dry air of a house in winter to the 

 damp air outside, the demands upon the mucous membranes are 

 very great and such frequent and violent changes certainly do harm 

 to susceptible people. Such rapid variations or alterations of the 

 humidity of the inspired air I think are as bad as would be rapid 

 alternations of altitude involving variations of several thousand feet. 



Some patients, however, seem to do better with a humidity greater 

 than that chosen for others. If we have a low relative humidity 



^ See W. Jarvis Barlow, M. D. : Climate in the Treatment of Pulmonary 

 Tuberculosis (Journ. Amer. Medical Association, October 28, 1911). 



