322 Professor Buckland on Artesian Wells. 



ammonia and carbonic acid, all affording elements of nutrition 

 to the vegetable kingdom. The water thus supplied at inter- 

 vals by rain from the clouds, was disposed of in four different 

 ways. The flood- waters of stormy weather, and the sudden 

 meltings of snow, were rapidly restored by rivers to the sea. 

 Another portion of the rain-water that fell upon dry land, was 

 evaporated from the surface of the soil, and so again taken 

 into the atmosphere, to mix with the vapour exhaled from- 

 rivers, lakes, and seas. A third portion supplied the drink- 

 and fluid nutriment of all animal and vegetable nature ; and 

 a fourth was disposed of to maintain the perennial supplies of 

 wells, and springs, and rivers. M. Arago states, that it has 

 been ascertained by an apparatus placed across the river at 

 Paris, that not one-third of the rain that falls on the district 

 that is drained by the basin of the Seine, returns directly by 

 that river to the sea, — the remaining two-thirds being applied 

 to the other purposes just mentioned. This most distinguished 

 astronomer had directed special attention to the investigation 

 of the economy of water in the natural world, and had illus- 

 trated it by the phenomena of the great Artesian well at Gre- 

 nelle, near Paris. He had not only foretold that water would 

 be found in this well, at an enormous depth below the chalk, 

 but that it would rise and overflow the surface ; accordingly, 

 it has risen in a large column 30 feet above the highest part 

 of Paris. M. Arago predicted also, that the temperature of 

 this water would become gradually higher, increasing about 

 one degree at every 45 feet below the surface. It now rises 

 from the depth of near 1800 feet, at the temperature of 91° 

 (Fahrenheit), warm enough to be applied to the heating of 

 green-houses and hospitals. 



In ancient days the difiicult scientific problem of the origin 

 of subterraneous water had occupied the attention of Aristotle 

 and Seneca, and their opinion was, that water was supplied 

 to springs by the action of central heat, causing it to ascend 

 towards the surface of the earth. This theory cannot be true 

 in the case of that large part of the earth's surface which is 

 formed of stratified beds of porous stone, permeable by water, 

 and alternating with impermeable beds of clay, through which 

 no water can ascend or descend. The condition of a water- 



