105 



If A B be taken sreater than one hundred, while A D remains ten, 

 or if we have any similar relation between the two, it will ))e more ad- 

 vantageous to use the Fourier's integral instead of the Fourier's series, 

 since for such a difference betAveen A li and A D the area ma}' he con- 

 sidered as an infinite strip. 



The results obtained are especially interesting in connection with the 

 motion of ground ^^ater, because of their bearing on the theory of ore 

 deposits, artesian wells and drainage flumes. The fact that sand through 

 which water is floAving, as before indicated, can be replaced by an ideal 

 liquid having a velocity-potential which is identical with the pressure 

 opens a new field of investigation in hydrodynamics from which many 

 important results Avill be obtained. 



Ti<^.-X 



