SUBTERRANEAN WATERS. 455 



€artli drinks in moisture by direct absorption from the atmos- 

 phere, by the deposition of dew, by rain and snow, by percolation 

 from rivers and other superficial bodies of water, and sometimes 

 by currents flowing into caves or smaller visible apertures.* 



of this island continent is drained by streams emptying into a central depres- 

 sion of the surface where their waters are spread over a wide expanse. Here 

 they are partly evaporated, and partly absorbed by deserts of sand beneath 

 which they collect, and are ultimately conveyed to the sea by natural subter- 

 ranean conduits. 



Two large, underground rivers, flovring respectively east and west from the 

 centre of the island to the sea, are said to have been encountered by miners- 

 or detected by artesian borings. This furnishes an explanation of the fresh, 

 water currents which burst out from the bottom of the sea at a considerable 

 distance from the Australian coast. 



A somewhat analogous fact has been observed in Southeastern Africa. Here, 

 according to Cooley, Phys. Oeog. , p. — , considerable streams, anciently flow- 

 ing in argillaceous formations, have in comparatively recent times cut through 

 their beds of tough clay, diffused their waters through the inferior more per- 

 vious strata, and left their original superficial channels quite dry. 



For an interesting account of the flow of subterranean currents of water in 

 Texas, see Academy, November 20, 1881, p. 370. 



* The great limestone plateau of the Karst in Carniola is completely honey- 

 combed by caves through which the drainage of that region is conducted. 

 Rivers of considerable volume pour into some of these caves and can be traced 

 underground to their exit. Thus the Recca has been satisfactorily identified 

 with a stream flowing through the cave of Trebich, and with the Timavo — 

 the Timavus of Virgil and the ancient geographers — which empties through 

 several mouths into the Adriatic between Trieste and Aquileia. The city of 

 Trieste is very insufficiently supplied with fresh water. It has been thought 

 practicable to supply this want by tunnelling through the wall of the plateau, 

 which rises abruptly in the rear of the town, until some subterranean stream 

 is encountered, the current of which can be conducted to the city. More 

 visionary projectors have gone further, and imagined that advantage might 

 be taken of the natural tunnels under the Karst for the passage of roads, rail- 

 ways, and even navigable canals. But however chimerical these latter schemes 

 may seem, there is every reason to believe that art might avail itself of these 

 all eries for improving the imperfect drainage of the champaign country 

 bounded by the Karst, and that stopping or opening the natural channels 

 might very much modify the hydrography of an extensive region. See in 

 Aus der Natur, xx., pp. 250-254, 263-266, two interesting articles founded on 

 the researches of Schmidt. 



The cases are certainly not numerous where marine currents are known to 

 pour continuously into cavities beneath the surface of the earth, but there is 

 at least one well-authenticated instance of this sort — that of the mill-streams 

 at Argostoli in the island of Cephalonia. It had been long observed that the 

 sea-water flowed into several rifts and cavities in the limestone rocks of the 



