Arctoxoski — Pleionian Cycle of Climatic Fluctuations. 33 



occurrence ot" the horme-pleion and the greatest development 

 of thermo-pleionian conditions in so many countries in different 

 parts of the world. 



The American anti-pleion is of particular interest, because 

 of the pleions observed in the Northwestern states, Alaska, 

 Canada and Greenland, as well as in the Southeastern states, 

 the West Indies and Mexico. In North America temperature 

 conditions were evidently in conformity with the horme-pleion, 

 except in the greatest part of the central portion of the conti- 

 nent. Moreover, it was precisely at the time of occurrence of 

 the horme-pleionian maximum, or soon afterwards, that the 

 greatest lowering of temperature was observed in the Middle 

 West from North Dakota down to Texas. 



Evidently the supposition that these abnormally low tem- 

 peratures were due to the veil of volcanic dust produced by the 

 Katmai eruption of June 6th, 1912, is completely out of the 

 question. If that had been the case, temperature would have 

 decreased from that date on, whereas it was decreasing for 

 more than a year before that date in order to reach the mini- 

 mum at the time of the occurrence of the horme-pleionian 

 maximum and accidentally at the time of the Katmai eruption. 

 The conclusion to be drawn from these facts is that the Ameri- 

 can anti-pleion of 1911-1912, corresponding in time with prac- 

 tically universally observed pleionian conditions, must have 

 been mechanically produced by abnormal pressure distribution 

 and the resulting abnormal winds. In other words, it seems 

 most probable to me that the anti-pleion observed in the United 

 States was simply due to changes of atmospheric circulation 

 clue to the exceptionally well-developed pleionian conditions in 

 the North as well as in the South of the States. The same 

 must have been the case of the other anti-pleions in New Zea- 

 land and in Russia, and perhaps in some other countries. But 

 precisely because these anti-pleions are to be considered as an 

 effect of dynamical reaction against the predominant pleionian 

 conditions, it is evident that they could not compensate the 

 action of the horme-pleion. 



The direct effect of fluctuations of solar activity upon atmos- 

 pheric temperature can also be observed in some of the details 

 of the horme-pleionian crest. The steps of the ascending 

 branch, corresponding to the means 1910:4 and 1910: 11, as 

 well as the minimum of 1912:3, may easily be distinguished 

 on many of the overlapping temperature curves. But even in 

 more minute details some of the curves present such similari- 

 ties with the solar curve, that a simple chance circumstance 

 can hardly be presumed, and that forcibly, wa must admit that 

 the cause of these temperature fluctuations is really a question 

 of ratio between solar faculse and umbrae. 



Hastings-on-Hudson, December, 1915. 



Am. Jour. Sci.— Fourth Series, Vol. XLII, No. 247.— July, 1916. 

 3 



