50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 65 



the glacial period may have been produced by a temporary decrease 

 in the*amount of carbon dioxide in the air. Even if this hypothesis 

 was at first founded upon assumptions for the absorption of carbon 

 dioxide which are not strictly correct, it is still an open question 

 whether an examination of the " protecting- " influence of the higher 

 atmospheric layers upon lower ones may not show that a decrease 

 of the carbon dioxide will have important consequences, owing to the 

 resulting decrease in the radiation of the upper layers and the in- 

 creased temperature gradient at the earth's surface. The problem 

 is identical with that of finding the position of the effective layer in 

 regard to the earth's radiation out to space. I propose to investigate 

 this subject in a later paper, with the support of the laboratory 

 measurements which will then be available. 



C OBSERVATIONS AT INDIO AND LONE PINE 



Knowing the influence of temperature upon the radiation of the 

 atmosphere, I can reduce the radiation values obtained at different 

 places to a certain temperature. The function giving the relation 

 between radiation and water-vapor content ought to be the same 

 for every locality. Reducing the observations at Bassour, at Lone 

 Pine, and at Indio (see tables VII and VIII) to 20 C, and plotting 

 the mean values, we obtain a diagram of the aspect shown in figure 

 5. The values from Algeria are given by the smooth curve. The 

 observations from Lone Pine (crosses) and the observations from 

 Indio (circles) deviate more or less from the Algerian curve. Con- 

 sidering, however, that they are founded upon a very limited number 

 of nights (Lone Pine 8, Indio 3), and that the mean deviation for 

 all points is very inconsiderable, the result must be regarded as very 

 satisfactory. 



In regard to the general meteorological conditions at Lone Pine, 

 it must be said that this place proved to be far from ideal for this 

 kind of observation, the principal purpose here being, not to collect 

 meteorological data, but to test a general law. The rapid changes 

 in temperature and humidity during the nights must have had as a 

 result that the atmosphere was often under very unstable conditions, 

 widely differing from what may be regarded as the average. This 

 is obvious also from the balloon observations of the U. S. Weather 

 Bureau, made simultaneously with my observations during a couple 

 of evenings at Lone Pine. These observations, made up to about 

 2,000 meters above the place of ascent, showed that there were often 

 considerable deviations from the conditions defined by " the con- 



