UNDERGROUND WATERS AS SOCIAL FACTORS. 615 



bottom not far from the shore. The limestone around Mont Ventoux 

 is riddled in a zone of seventy kilometres by natural wells and unfathom- 

 able pits, many of which bear names well known in the local legends. 

 The waters which these rocks have stored up are poured out at their 

 lowest point, and give rise, in a picturesque grotto, to the copious 

 fountain of Vaucluse, which was formerly regarded as a beneficent 

 divinity. Compared with the depth of the rains at different stations 

 in the basin, the mean outflow of the fountain indicates a volume 

 of infiltration equal to about six tenths of the quantity of rain-water. 

 The limestone under the valley of the Loire, at Orleans, is plowed 

 by interior currents from which the water-supply of the city is directly 

 taken. The waters begin to be lost at a point some forty kilo- 

 metres above the city, and return to the river about thirty kilometres 

 below. The Iton, in the department of the Eure, fails to flow over 

 the surface for several kilometres, and is called the Sec-Iton, or dry 

 Iton ; but its waters are reached in their subterranean course by exca- 

 vations of twenty metres. Similar facts may be observed in all parts 

 of the globe. By a similar kind of drainage the cavernous limestone 

 of the Apennines gives rise to the Aqua Martia, which was brought to 

 Rome B, c. 608 by the consul Quintus Marcius, and which still con- 

 tinues to be of prime importance to the city ; " the most celebrated 

 water in the universe," enthusiastically says Pliny, "a franchise of 

 salubrity, one of the benefits granted to Rome by the favor of the 

 gods." 



A grain of truth sometimes lies at the bottom of the ancient 

 fictions. Was not the observation of water-courses which are ingulfed 

 and appear again the origin of the fable of the fountain of Arethusa, 

 which the Greeks regarded as the reappearance of the river Alpheus? 

 After a pursuit from Peloponnesus across the Ionian Sea, it was sup- 

 posed to overtake the nymph personified in this fountain at the moment 

 when it gushed out near Syracuse. 



Besides moving through the interstices, fissures, and cavities of the 

 crust of the globe, water exists everywhere in another state, in which, 

 although quite invisible, it is of hardly less importance. All rocks, 

 including the most compact ones, inclose water within their pores, 

 however minute they may be, where it is held by capillary attraction, 

 and is not apparent to our instruments of highest magnifying power. 

 But it may be disengaged by desiccation, when the rock will be found 

 to have lost a sensible fraction, some ten thousandths at least, of its 

 weight. At the same time some of the qualities of the rock are modi- 

 fied ; for workers in slate, sandstone, and other rocks find it a matter of 

 great difference, in the facility of their tasks, whether these stones still 

 hold their quarry-water or have been dried in the air. The Romans 

 availed themselves of the porosity of the onyx to soak it in certain 

 liquids which would enliven the color of the stones that they used in 

 their cameos. Under this form of intimate latent impregnation, 



