28 



ATMOSPHERIC ACTINOMETRY 



observations made by Mr. Elfving. or as it may come to us after a warm day or a 

 period of great heat, wliicli may have increased tiie invisil)le ch)ud of terebinthine 

 vapors or other odoi-oiis essences. But, I repeat, all these points must be investi- 

 gated directly, and this preliminary study, although it has continued for many 

 years, has no other claim than that of suggesting new subjects for the study of the 

 atmosphere. 



Let us now return tn the comparison of the effects which ciiual periods of 

 exposure have in Fiance and in Fiidand. The following are '.he results obtained 

 by Mr. Klfviiiii at llelsingfors, during the same period of the same year: 



HELSINGFORS, 1 888. 



The regularity is here greater than in France, and what is especially remark- 

 able is the close resemblance in an actinometiic sense of the days which ai'e marked 

 as "similar," in the colmiin of "Remarks" (Aug. 29th and 30th, Sept. 2d and 3d, 

 14th, 15th, IGth, and ITtli). But what is perhaps most striking in this table, when 

 compared with that on page 26 is that the figures of solar combustion are notably 

 higher than they were in France at Mont Doie, at the same time of the year. 

 Still, Finland is very I'ich in resinous woods, and even if the station were less sur- 

 rounded by them than at Mont Dore, the altitude is lower, which to some extent 



