123 



or so irregular, as not to be immediately referable to any 

 well-defined law. These points on the surface of the earth 

 may be regarded as nodal points in the general system of 

 circulation of the great currents of the atmosphere. 



Among the places at which it seemed to me likely that 

 the law of change in the relative amounts of rainfall under 

 different winds would be found to differ considerably from 

 that which prevails at Oxford is St. Petersburg. I there- 

 fore extracted from the volumes of the Annales de VOhser- 

 vatoire Physique Central de Russie the amounts of rain 

 which fell under different winds at St. Petersburg during 

 the eleven years 1854-64. The results are shown in the 

 following table : — 



Rainfall under different Winds, at St. Petersburg 

 DURING A Solar Spot Period. 



From the mean values in the last line of this table it 

 appears that there was a principal maximum of rainfall 

 under west winds, and a secondary maximum under south- 

 east winds ; a principal minimum under east winds, and a 

 secondary minimum under south winds. 



In the eleven years 185^-6 4 the number of groups of 



