SPRINGS. 263 



of the oxygen and hydrogen gases, which decompose each other, and produce water ; and 

 to the filtering of water from the sea into internal cavities and reservoirs prepared by 

 nature, from whence they make their way to the surface. Some writers contend for the 

 former cause exclusively. Marriotte has examined the point, whether the quantity of 

 rain water is sufficient to feed all the springs and rivers, and so far from finding a defi- 

 ciency, he concludes upon the amount being so great as to render it difficult to conceive 

 how it is expended. According to experiments which have been made, there falls 

 annually upon the surface of the earth about 19 inches of water, but to render his 

 calculation still more convincing, Marriotte supposes only 15, which makes 45 cubic feet 

 per square toise, and 238,050,000 cubic feet per square league of 2300 toises in each 

 direction. Now the rivers and springs which feed the Seine, before it arrives at the 

 Font-Royal at Paris, comprehend an extent of territory, about 60 leagues in length, and 

 50 in breadth, which makes 3000 leagues of superficial area ; by which, if 238,050,000 

 be multiplied, we have for the product 714,150,000,000, for the cubic feet of water 

 which falls, at the lowest estimate, on the above extent of territory. Let us now examine 

 the quantity of water annually furnished by the Seine. The river, above the Pont-Royal, 

 when at its mean height, is 400 feet broad, and 5 deep. When the river is in this state, 

 the velocity of the water is estimated at 100 feet per minute, taking a mean between the 

 velocity at the surface, and that at the bottom. If the product of 400 feet in breadth, 

 by 5 in depth, or 2000 square feet, be multiplied by 100 feet, we- shall have 200,000 cubic 

 feet for the quantity of water which passes in a minute through that section of the 

 Seine above the Pont-Royal. The quantity in an hour will be 12,000,000; in a day 

 288,000,000 ; and in a year 105,120,000,000 cubic feet. This is not the seventh part of 

 the water which, as previously stated, falls on the extent of country that supplies the 

 Seine, the large remainder, not received by the river, being taken up by evaporation, 

 besides a prodigious quantity employed for the nutrition of plants. A further calculation 

 has been made by the same writer, of the water which ought to be furnished naturally 

 by a spring that issues a little below the summit of Montmartre, and which is fed by an 

 extent of ground 300 toises in length, and 100 in breadth ; making a surface of 30,000 

 square toises. At the rate of 18 inches for the annual quantity of rain, there will fall on 

 that extent an amount equal to 1,620,000 cubic feet. A considerable part of this water, 

 perhaps three-fourths, immediately runs off, so that no more than 405,000 forces its way 

 through the earth and sandy soil, till it meets with a bed of clay at the depth of two or 

 three feet, from which it flows to the mouth of the fountain, and feeds it. If 405,000 

 therefore be divided by 365, the quotient will be 1 100 cubic feet of water, which it ought 

 to furnish daily, or about 38,500 French pints. This makes about twenty-seven pints 

 per minute, which is nearly the produce of the spring. 



It appears from this and other calculations, that the rain which falls in particular 

 districts is more than sufficient to account for all their springs and rivers ; and some very 

 obvious circumstances show that the origin of springs is almost, if not entirely, owing to 

 the rains which continually moisten the surface of the globe. In seasons of long drought, 

 the greater part decrease in a considerable degree, and some absolutely fail, while they 

 are renewed in the same progression as the descending showers are abundant. It is 

 possibly the case, indeed, that the ocean filtering through pores of the earth the salt 

 particles being lost in the passage may give rise to many springs ; but as the preceding 

 cause is amply sufficient to explain their formation, we need not recur to any other. The 

 rains and melted snow which the earth absorbs, percolate through crannies, or ooze 

 through the strata, and collect in vast internal reservoirs in mountainous regions, from 

 which the superabundant water finds its way again to the surface, breaking out through 

 fissures in the side and at the bottom of the hills. Copious springs thus issue from the 



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