ARCrOWSKI, VOLCANIC DUST VEILS 



167 



as a standard. Moreover, in my previous publications I have shown that 

 the consecutive means observed at Arequipa express very well the normal 

 pleionian variation and may serve as a standard in all cases of comparison. 



In the accompanying diagram (Fig. 6) the consecutive temperature 

 curves along the Pacific coast are represented, together with the ^Mauritius 

 and Arequipa curves. The latitudes 

 of Fort Liscum, Sitka, Loring and 

 Victoria are: 61° 2', 56° 50', 55° 

 32' and 48° 26' K 



The occurrence of the eruption 

 coincided with the pleionian crest of 

 Arequipa. For Arequipa the con- 

 secutive mean of July, 1911, to 

 June, 1912, is the highest. From 

 then on the temperature decreases 

 until the consecutive mean of Octo- 

 ber, 1912,-September, 1913. The 

 same is true at Mauritius ; but there 

 the pleionian crest is very different 

 from what it is at Arequipa — it is 

 flat. Since the same may be ob- 

 served ^on the curve of Victoria, the 

 apparent depression of the crest of 

 this station cannot be ascribed with- 

 out hesitation to the effect of the 

 Katmai haze. 



The other curves — the Fort Lis- 

 cum curve in particular — resemble 

 the Arequipa curve so very much 

 that we may admit that at least the 

 depression of the values from the 

 mean of August, 19 11, -July, 1912, 

 to the mean of December, 1911,-No- 



vember, 1912, is due to the effect of volcanic dust. The dotted lines 

 indicate the portions of the pleionian crests which may have been de- 

 pressed. 



The cun'es of the stations at Xome, Tanana and Fairbanks, situated 

 north of the Alaskan range, do not seem to have been affected, and that 

 of Eagle but slightly. Tn the case of Edmonton, it is difficult to decide. 



Fig. 6. 



-Arequipa pleion of 1911-1912 

 otserved in Alasl'a 



