MAGNETIC OR ELECTRIC CAUSE OP CYCLONIC STORMS 525 



part of America, in about latitude 50°, across tliat continent to Europe 

 and as far as the confines of Asia, where it gradually dies out. Here, 

 just as in the southern hemisphere, the average path of the storm does 

 not follow an arc concentric with the pole of rotation, but one much more 

 nearly concentric with the magnetic pole. Finally, in Siberia, there is a 

 minor magnetic pole. Corresponding to this there is a third stormy area 

 which centers in Japan. Another fact which Kullmer points out as per- 

 haps of importance in this connection is that in the Atlantic Ocean the 

 lines of equal total intensity of magnetic force follow the same direction 

 as the main storm tracks. The relation between the location of storms 

 and the magnetic pole is brought out in most of the storm maps. Heavy 

 solid lines have been drawn with the magnetic pole as a center. In North 

 America the more northern line is drawn at a distance of approximately 

 25° from the magnetic pole. It does not run exactly parallel to the belt 

 of maximum storminess or to the belt where storminess increases most 

 rapidly during times of sun-spot maximum. N"evertheless there is a cer- 

 tain degree of correspondence. In figure 6 a southern line has been drawn 

 about 38° from the magnetic pole. It does not agree with the so-uthern 

 storm belt to anything like so great a degree as does the other line with 

 the northern storm belt, perhaps because the central protuberance of the 

 northern belt pushes the storms unduly far to the south. Its continuation, 

 however, is the more northerly line in the European maps. This, as may 

 be seen in figure 4, lies not far from the main northern area of abundant 

 storms. 



How significant this possible agreement of magnetic and cyclonic phe- 

 nomena may be can not yet be determined, but it is certainly worth in- 

 vestigating. The earth's magnetic field is closely connected with that of 

 the sun. It is well known that among all the phenomena of the earth 

 magnetism is the one which shows the most unequivocal connection with 

 the solar changes which manifest themselves as sun-spots, protuberances, 

 and other variations in the solar atmosphere. Hence, if cyclonic storms 

 are in part a magnetic phenomenon, we should expect to find that they 

 vary in harmony with the spots of the sun. Such variations would prob- 

 ably be also in harmony with changes in the amount of solar radiation, 

 but they would not be due to it primarily, and might be of considerable 

 magnitude when the temperature changes were slight. Although physi- 

 cists are slow to believe that solar temperature can change rapidly, they 

 all agree that electrical and magnetic changes may take place with great 

 speed. These considerations are highly speculative and they are not 

 essential to our main conclusions. They are of value, however, as sug- 

 gesting some of the lines along which investigation may prove fruitful. 



XXXVTTT— Bull. Gkol. Soc. Am., Vol. 25, 1913 



