206 proceedings: philosophical society 



amount of heat energy received at the surface of the earth. The dim- 

 inution in insolation has had a coohng effect on the temperature of 

 the northern hemisphere as a whole, but in regions where storms are 

 frequent and atmospheric circulation vigorous, this circulation has de- 

 termined the character of the local temperature and, in some cases, has 

 brought it above the normal rather than below. The paper was dis- 

 cussed by Messrs. Abbot and Bowie. 



Mr. F. E. FowLE then presented an illustrated paper on Atmospheric 

 transparency for radiation. The transparency of the atmosphere on 

 clear days is dependent on scattering due to three obstructions: the 

 molecules of the air itself (dry air), the hindrances associated with water 

 vapor (wet haze), and ordinary dust (dry haze). It is due to the change 

 in these last two factors with the altitude that the quality of the trans- 

 parency of the air, even with homogeneous rays, changes and that 

 Bouguer's formula for atmospheric transmission may not be used in 

 passing from one altitude to another. Above an altitude of 1000 meters 

 on clear days the dry haze may become a negligible factor and the for- 

 mula developed by the speaker can be used to compute the transparency 

 to within 1 per cent. Above Mount Whitney (4420 meters) the wet 

 haze on clear days may also become negligible. The paper was dis- 

 cussed by Mr. Abbot. 



Mr. W. W. CoBLENTZ then presented a paper on The exudition of ice 

 from plants. Lantern slides were shoAvn illustrating some beautiful 

 forms. Messrs. Abbot, Wright, and Waite discussed the paper, partic- 

 ularly as regards' the cause of the phenomenon noted. 



J. A. Fleiviing, Secretary. 



