740 C. R. VAN HISE 



upon the motion of groundwaters showed me that this was an 

 entirely unnecessary assumption, and gave me the additional data 

 needed upon this point. This chart (Fig. I ) is a horizontal dia- 

 gram. A represents one well and B another well, separated by a 

 homogenous porous medium. Into the well B, I pour water. In 

 the well A there is no water at the outset ; and the water flows 

 from the well B to the well A through the medium. What 

 is the path of the water ? Its flowage is represented by the 

 curved lines. Some of the water goes in a nearly direct course. 

 Another part takes a somewhat curved course. Still other parts 

 of the water follows a very indirect course, represented by the 

 longer curved lines. All of the available cross section is 

 utilized. If for instance this room were filled with water, and 

 water were running in at one place in the front end of the room 

 and were escaping at one place in the rear end of the room with 

 equal speed, would the water simply follow the direct line 

 between the two ? You know perfectly well it would not. The 

 entire available cross section of the room would be utilized, 

 although the more direct course would be utilized to a greater 

 extent than the more indirect course. This is intended to be 

 illustrated on the chart (Fig. i) by the lines representing the 

 nearly direct courses being close together, and the lines repre- 

 senting the indirect courses being farther apart. 



This chart (Fig. i) then represents the horizontal circula- 

 tion. If we pass to the vertical circulation the flowage is repre- 

 sented by this chart (Fig. 2). The water is being poured into 

 the well B and passes to the well A. The water follows the 

 course of the curved lines, so that with a difference in head 

 equal to the difference in the level of the water in the two wells, 

 a considerable part of the water being poured into B and passing 

 through the homogenous porous medium to A penetrates a con- 

 siderable depth, from which it rises and enters the well A. Now 

 what will be the limit in nature of the downward search of 

 underground water ? We have already given it. Manifestly 

 the lowest limit of effective circulation at any place is the bot- 

 tom of the zone of fracture at that place. The zone of flowage 



