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soils of the prairies, it stands for some time in pools. such as those called "hog wallows" in Texas.

The capacity of rocks for the transmission of water is entirely different from their capacity for imbibition. If one could construct of sand, clay, slate, granite, chalk, and close textured limestone filtering vessels of equal capacity, and then fill them with water, one would find diverse results, illustrating the capacity of these rocks for transmission of water. Water would pass so slowly through the close textured limestone, slate, and granite that the quantity filtered would be practically imperceptible. At first the sand and chalk would drink in the water equally fast, but after complete saturation it would require longer time for the water to percolate through the chalk than through the sand.

The distribution of underground water is dependent upon the arrangement of rocks in sheets or strata. By a simple arrangement of the porous sands between impervious materials, nature has constructed reservoirs and conduits for the retention and distribution of water, and it is by the character of the arrangement of the rock sheets that the negative or positive conditions for the procurement of artesian waters are determined.

A stratum usually consists of two related parts the outcrop and the embed. That portion exposed at the surface of the earth is the outcrop, and that portion which is concealed underground beneath and between the other rocks may be termed the embed. The outcrop of a water bearing stratum constitutes its main catchment or receiving area, and the embed constitutes the storage reservoir.

If the water bearing rock sheet is inclosed between impervious beds, and inclines beneath the surface, the water will be conducted to a lower level than the outcrop and will remain stored in the earth under hydrostatic pressure until an outlet is provided for it. A water impregnated stratum embedded in this manner is an artesian reservoir. The water bearing strata, together with the impervious strata beneath and above them, constitute an artesian system.

When water is conducted downward to a lower level by an embedded stratum, it acquires a tendency, due to hydrostatic pressure, to rise higher than the overlying retaining bed. When the beds overlying such a water bearing stratum are penetrated by an opening, artificial or natural, the contained water will rise through the overlying bed. Such earth waters which rise under the influence of hydrostatic pressure through an opening to a higher level are known as artesian waters. Hence an artesian well may be defined as one in which the water rises by means of hydrostatic pressure above the top of the embed. If artesian waters rise to the surface, they are known as flowing artesian wells; if the water fails to rise to the surface in a well, such a well is known as a nonflowing artesian well. The height to which the water will rise depends upon several conditions. If the water bearing stratum is embedded and incised at only one place down the dip from its surface outcrop, the water at the place of incision will rise to the same level as