DISTKIBUTION OF EAKTHQUAKES IN TIME. 263 



Earthquakes and sun spots, — Of late years con- 

 siderable attention has been drawn to a coincidence 

 between the occurrence of sun spots, magnetic disturb- 

 ances, rainfall, and other natural phenomena. 



These periods of sun spots occur about every eleven 

 years, and appear to be coincident with the periodical 

 return of the planet Jupiter. In Japan, Dr. E. Naumann 

 sought for a coincidence between these periods of sun 

 spots and earthquakes, but without any marked results. 



Schmidt, who carefully compared his lists of earth- 

 quakes with the appearance of sun spots, came to the 

 conclusion that there was no marked coincidence. The 

 occurrence of earthquakes had sometimes synchronised 

 with sun spots, whilst at other times there had been a 

 maximum of sun spots and no earthquakes. 



M. R. Wolf ^ apparently considers that earthquakes, 

 like volcanic eruptions and the appearance of the aurora, 

 are coincident with sun spots. 



Kluge, however, came to the conclusion that when 

 there are few sun spots, earthquakes, like volcanic 

 eruptions and magnetic disturbances, have been at a 

 maximum. 



M. A. Poey, who examined a catalogue of the earth- 

 quakes of Mexico and the Antilles, extending from 1634 to 

 1870, shows by a table that earthquakes have come in 

 groups, first at the maxima and then at the minima period 

 of sun spots. Out of thirty-eight groups, seventeen being 

 at the maximum and seventeen at the minimum, the re- 

 maining four are exceptions to the rule, being between the 

 maximum and minimum. Phenomena which are depen- 

 dent upon heat occur with the minima of sun spots, and 

 those dependent upon cold with the maxima.^ 



^ Bern. Natwrf. Gesellschaft, 1852. 



"^ Com2)tes Rendus, 1874, Jan. to June, p. 51* 



