634 PROCEEDINGS OF THE NEW YORK MEETING 



Essentials of Artesian Flows: 



I. An adequate source of water supply. 

 II. A retaining agent offering more resistance to the passage of water than 

 the well or other opening. 

 III. An adequate sovirce of pressure. 



The first requisite is not made specific as regards source, as artesian waters, 

 as has been pointed out, are not derived from a single but from a variety of 

 sources. In the case of the second requisite the retaining agent may be a 

 stratum, a vein or dike-wall, a joint, fault, or other fracture plane, a water 

 layer, or some one of a variety of other agents. The pressure, while primarily 

 due to differences in level in the different parts of the artesian system, may be 

 transmitted in such a variety of ways and is subject to so many modifying 

 factors that the specification of a definite source is impracticable. 



Modifying Factors 



It is believed that the three factors of the preceding paragraph are all that 

 can be considered as essential to artesian flows, all other postulated requisites 

 being in reality modifying or accessory rather than essential factors. These 

 secondary factors, which have been enumerated in the preceding pages, may be 

 classed as follows : 



Secondary Factors of Artesian Fi,ows 



I. Hydrostatic factors (relating to pressure and movement). 



1. Factors mainly affecting pressure. 



a. Barometric. 

 h. Temperature. 

 ,r. Density. 

 d. Rock pressure. 



2. Factors mainly affecting movement. 



a. Porosity. 



h. Size of pores or openings, 

 c. Temperature. 

 II. Geologic factors (relating to reservoir). 



1. Chai-acter of reservoir. 



2. Retaining agents. 



3. Structure of reservoir. 



4. Topographic conditions. 



5. Conditions relating to supplj\ 



a. Catchment conditions. 



7>. Conditions of underground feed. 



6. Co.nditions of leakage. 



No remarks on this paper. 



