REVIEWS 89 
Principles and Conditions of the Movement of Ground Water. By 
FRANKLIN Hrram Kino, with a theoretical Investigation of 
the Motion of Ground Waters, by CHARLES SUMNER 
SUICHMER. | Lxt. Nineteenth Anna wep, US: Geol: Survey, 
Pare 1) 1809) pp. Ixi-- 3384) 
This important paper bears throughout evidences of the painstak- 
ing industry that marks all of Professor King’s work. It deals first 
with general considerations relative to the amount of water stored in 
the ground in different kinds of rock. For the Dakota sandstone he 
assigns 15 to 38 feet of water for every 100 feet in thickness of the 
rock. The water in the Potsdam sandstone of Wisconsin and 
adjoining states he makes equivalent to an inland submerged sea 
having a mean depth of 50 to 190 feet of water for the area occupied. 
In regard to the’superficial soils and sands, Professor King gives more 
detailed data, as this lies in his special field of investigation. A saturated 
sand carries from 20 to 22 per cent. of its dry weight of water, while the 
soils and clays range from these values all the way up to 40 and even 
50 per cent. of their dry weights. “‘Since a cubic foot of dry sand 
weighs from 102 to 110 pounds, while soils, clays and gravels range 
between this and 79 pounds, we have a ready means of expressing 
quantitatively the water which is continually stored in this mantle of 
loose material when it lies below the plane of saturation.” Ina table 
of actual determinations where loamy clays and very fine sandy soils 
are involved, 2 feet of water in 5 feet of soil below the horizon of sat- 
uration are shown. When soil does not lie below the plane of satura- 
tion it usually contains 75 per cent. of the amount required for full sat- 
uration, except during dry times when a surface layer of one to five feet 
thick falls below this. Even where the plane of saturation lies below 
a large thickness of soil there is still a large storage capacity for 
water. 
In rocks other than sandstones and soils the percentage is usually 
very much smaller. Its cumulative magnitude is indicated by the state- 
ment that so small an amount of water as 0.0023 of the weight for 5000 
feet of the earth’s crust is large enough to form a continuous sheet 
about the globe 30 feet deep. It is believed that water penetrates the 
crust to depths even exceeding 10,000 feet. Reckoned at 1 per cent., 
with a specific gravity of rock of 2.65, the amount contained would be 
a layer 265 feet thick. Of course the amount in the upper horizons is 
