ARTESIAN WELLS. 565 
Briickmann in Germany.* It appears that there 
are extensive districts in various parts of Europe, 
where, under certain conditions of geological 
structure, and at certain levels, artificial foun- 
tains will rise to the surface of strata which throw 
out no natural springs,! and will afford abundant 
supplies of water for agricultural and domestic 
through the London Clay, either into sandy beds of the Plastic 
Clay formation, or into the Chalk ; such as those represented at 
D. E. F. G. H. I. If the Perforation be made at G. or H. where 
the surface of the country is below the line A. B. the water will 
rise in a perpetually flowing Artesian fountain, as it does in the 
valley of the Thames between Brentford and London. 
* See Hericart de Thury's Considerations sur la cause du 
Jaillissement des Eaux des puits fores, 1829. 
Notices scientifiques par M. Arago. Annuaire, pour I'An. 1 835. 
Von Bruckmann iiber Artesische Brunnen. Heilbronn am 
Neckar, 1833. 
t The Diagrams in PI. 69, Figs. 1 and 2. are constructed to 
illustrate the causes of the rise of water in natural, or artificial 
springs, within basin-shaped strata that are intersected by the 
sides of Valleys, or traversed by Faults. 
Supposing a Basin (PI. 69, Fig. I.) composed of permeable 
strata, E. F. G. alternating with impermeable strata, H. L K. L. 
to have the margin of all these strata continuous in all direc- 
tions at one uniformly horizontal level A, B, the water which 
falls in rain upon the extremities of the strata E, F, G, would ac- 
cumulate within them, and fill all their interstices with water up 
to the line A, B ; and if a Pipe were passed down through the 
upper, into either of the lower strata, at any point within the 
circumference of this basin, the water would rise within it to the 
horizontal line A, B, which represents the general level of the 
margin of the Basin. A disposition so regular never exists in 
nature, the extremities or outcrops of each stratum are usually 
at different levels. Fig. 1. a. c. e. g.) In such cases the line a. b. 
