326 



REPORTS ON THE STATE OP SCIENCE. 1920. 



Again, the changing declination of the moon introduces the principal variation in 

 daily mean level, in the form of a constituent of speed 



2(r, 



which with the first order elliptic inequality gives two more of speeds 



2(r ± (<r — tir). 



The amplitudes of all the constituents depending on the inclination of the moon's 

 orbit to the equator vary with tlie position of the node on the ecliptic. As the 

 monthly mean level also depends on the inclination of the moon's orbit to the 

 equator, we have a small constituent with a speed N equal to that of revolution of 

 the moon's nodes. 



The speeds of the constituents of solar origin may be similarly determined, but 

 only the declinational and tirst order elliptic effects on the primary constituent need 

 be considered. 



4. On collecting the results we have the following tables. The constituents of 

 the same species have similar geographical distributions of generating potential ; 

 they are arranged in decreasing order of magnitude. The symbols are the same as 

 those in general use, with the exception of ir,, which is now introduced for the first 

 time. The corresponding amplitude in the generating potential is larger than that 

 of some constituents given in the other species. All the constituents given in the 

 tables have, according to Darwin, larger amplitudes in the generating potential than 

 any omitted. 



Semi-diurnal Species. 



