Flow of Ground Water. 



267 



these relations being realized in experiment, in some cases 



the flow being systematically too fast and in others too slow. 



A series of observations by Welitsehkowsky and Wollny 



FIG. 97. Showing apparatus of Welitschkowsky and the relation of pres- 

 sure to flow of water observed by him. 



and the apparatus with which they were secured are repre- 

 sented in Fig. 97. It will be observed that where the col- 

 umns of sand used by Welitschkowsky were 25 c. m. and 



