ATMOSPHERIC ACTINOJIETRY 



ST. PIERRE 1.E PORT, 1 887. 



Here again the solar combustion iiicfeases with the fine weather anil diminishes 

 when the .sky is overcast or rain falls. Although the weather was on an average 

 less fine than during the corresponding series of exi)eriinents cited before, the latter 

 gives, on the average, higher results, a fact which confirms what we have already 

 said concerning the actinometric differences of different years at the same epoch. 

 Here are now the expei'iments made by Mr. Elfving at the same time in 1887 : 

 Helsingfors, latitude 60° 10'. Length of day, 14 hours. Height of the suu 

 above the hoiizon at noon, about 38°. 



.Solar Combustion. 



" The difference between the first three days and the two othei'S is quite great ; 

 it arises, no doubt from the fact that the atmospheic had I)C('n purified by heavy 

 rains on Augu.st 30th and September Istand 3d. In March, I had already observed 

 this effect of rain." (M. Elfving.) 



The figures in the first column are on an average higher than those Avhicli coi'- 

 respond to them in the preceding rejioi-t, and this superiority must be all the more 



