The Tide-generating Forces 



271 



localities during two months. The decrease in amplitude as compared to the 

 theoretical value is approximately identical at both localities, except that 

 Marburg lags behind the moon by 1 h, whereas Berchtesgaden precedes it by 



O -I 



Lunar hours, T 



Fig. 116. Variation in the force of gravity for the lunar tide M 2 at Marburg a. L. (— o— o— ) 



and Berchtesgaden (—•—•—) compared with the values computed for a rigid earth ( for 



Marburg, for Berchtesgaden). Passage of the moon through the meridian at 9 h. 



approximately 1 h. Hence, it is proven that there are also variations of the 

 vertical components of the tidal forces. 



In connection with the results of the measurements with horizontal pen- 

 dulums, it has become possible to get an idea of the elastic tides of the solid 

 earth, which is of great importance for geophysics. 



For further details we refer to the textbooks on geophysics. 



