THE SUN AND SUNSPOTS MAUNDER 



173 



This fact has a bearing on the rotation periods of the sun given 

 by magnetic storms. It implies that it is not possible to determine 

 with any degree of certainty the particular zone of solar latitude, 

 from whence a pair of magnetic storms have arisen, merely by notic- 

 ing the interval in time that has occurred between them. Thus 

 Table II gives for 190 pairs of storms occurring between 1848 and 

 1913, and for spots from 1879 to 1901, the degrees of favor shown 

 for the various synodic periods. 



Table II 



It is evident that both spots and magnetic storms concentrate 

 sharply upon a synodic period of 27.1 days. 



The representations of the corona, shown in Plates 1-7, are draw- 

 ings made from photographs taken by Mrs. Maunder in 1898 in 

 India, and in 1901 in Mauritius. A drawing of the former was 

 made by the late Mr. W. H. Wesley ; the drawings from the Mauritius 

 eclipse were made by Miss Beatrice Handler. In the latter it will be 

 seen that there are two leaflike formations, each covering a very 

 disturbed arc of about 60°. In the complete corona of longer ex- 

 posure, the apex of each leaf is shown, but while that of the more 

 northern is prolonged radially out into a beam, the apex of the more 

 southern is directed somewhat toward the equator, so that the beam 

 as a whole is inclined to the normal. In the small-scale photo- 

 graph, that taken in India in 1898, we see one of the beams pro- 

 longed into a straight rodlike ray; straight to as great a distance 

 as it can be distinguished upon the photograph. A recent paper by 

 Mr. E. A. Milne on " The average life of an excited calcium atom " 

 (Monthly Notices, 84, March, 1924) gives some idea of the way 

 in which such rays arise in the disturbed sun-spot zones and how 

 their particles escape outward from the sun. 



