DISTRIBUTION OF EARTHQUAKES IN TIME. 251 



and moon, any coincidence between the phases of these 

 bodies and the occurrence of earthquakes more or less 

 involves a time relationship with the other phenomena 

 resultant on lunar and solar influences. 



Earthquakes and the position of the moon. — Many 

 earthquake investigators have attempted to show the 

 connection between earthquakes and the phases of the 

 moon. 



The first and most successful worker in this branch of 

 seismology was Professor Alexis Perrey, of Dijon, who, after 

 many years of arduous labour in tabulating and examining 

 catalogues of earthquakes, showed that earthquakes were 

 more likely to occur at the following periods than at 

 others. 



1. They are more frequent at new or full moon (syzy- 

 gies) than at half moon (quadratures). 



2. They are more frequent when the moon is nearest 

 the earth (perigee) than when she is farthest off (apo- 

 gee). 



3. They are more frequent when the moon is on the 

 meridian than when she is on the horizon. 



These results were obtained by Perrey after analysing 

 his catalogues by three different and independent methods, 

 and they were confirmed by the report of a committee 

 appointed by the Academy of Sciences. It must, how- 

 ever, be remarked that in several instances anomalies 

 occur, and also that the difference between the number of 

 earthquakes at any two periods is not a very large one. 

 Thus, for instance, the annual catalogues compiled by 

 Perrey from 1844 to 1847, the earthquakes in perigee are 

 to those in apogee as 47 : 39. Between the years 1843 

 and 1872 Perrey finds that 3,290 shocks occurred at the 

 moon's perigee, and 3,015 at the apogee.^ 



» Compte Rendus, 1875, p. 690. 



