HYRDROLOGY. 151 



S- Those from the St. Peters sandstone. This is by far the most 

 widely available, and, except locally, the most important source of Ar- 

 tesian wells in eastern Wisconsin. The lower layers of the Trentou 

 limestone, resting upon it, form an efficient confining sheet above, 

 and the formations below are saturated by water having a higher 

 source than that of the St. Peters sandstone, so that there can be no 

 loss, but may be gain from beneath. Aside from the porous charac- 

 ter of the sandstone, it is much fissured in vertical, oblique and ir- 

 regular directions, enabling the water to readily traverse it. From 

 this horizon arise the deeper seated fountains at Watertown, Wild's 

 well and several more recently sunk at Pond du Lac, the " oil well " 

 at Palmyra, the exceptionally saline well at Sheboygan, and those at 

 Milwaukee, Racine aibd Western Union Junction. 



6. Those from the primordial zone. The well at the Northern 

 Hospital for the Insane, at Oshkosh, represents this class. The pub- 

 lic well on Algoma street, Oshkosh, the water of which, though it does 

 not flow at the surface, rises within a few inches of it, may be also 

 classed here. So also the well on the Fair Grounds at Janesville, 

 which flows through the aid of hydraulic appliances. A portion of the 

 flow of the Kacine well is from this horizon. 



These six classes, it may again be remarked, furnish the most sys- 

 tematic grouping for study and description, but it will doubtless be 

 most convenient and interesting to the people of the state for whose 

 beneflt the survey was instituted, to describe these wells by the local- 

 ities in which we flnd them situated. 



In number and variety of source, the flowing wells of Pond duLac 

 stand preeminent. They represent four of the six systems above 

 mentioned. The accompanying profiles represent much more clearly 

 and satisfactorily the conditions under which these fountains are se- 

 cured than an elaborate description, and will only need to be sup- 

 plemented by some additional and explanatory statements. And I 

 desire here to express my special indebtedness for many facts, other- 

 wise beyond my reach, to Mr. C. O'Connor, who has sunk many of 

 these wells. From his statements it appears that there are three 

 classes of comparatively shallow wells that derive their flow from 

 within twenty feet of the surface of the rock, either above or below 

 it, it being from two to nearly one hundred feet beneath the soil. In 

 the first, flowing water is found in the blue clay which underlies the 

 superficial red clay. The water is usually reached in a stratum of 

 quicksand, from six inches to six feet in thickness. In the second, 

 the flow is obtained between what is locally known as the "concrete" 

 and the rock. This concrete, which varies from two to twenty feet 



