114 On Artesian or Ovcrjlowing Wells. 



work of Garnier, it only requires to be mentioned that, among 

 the many streams of water which issue forth with much vio- 

 lence from the fissures in the limestone rock of the steep decli- 

 vity of Cap-blanc-nez, and which are constantly undermining 

 it, also another proof of the existence of more extensive ex- 

 cavations in this district, and which are continually becoming 

 larger, is in the sinking of the ground, — for example, in the 

 arrondissement of S. Paul, being a not unfrequcnt occurrence. 

 If we now reflect, the limestone strata have a position inclined 

 to the horizon, and that their outgoing often forms the highest 

 point of the district, there can be no doubt that the Artesian 

 wells are only supplied by the atmospheric water, which falls 

 on the upper part of the limestone strata, and sinks down 

 through the various canals which they contain : in a word, that 

 they represent the shorter legs of a syphon, the longer of which 



subterranean canals in limestone mountains, is certainly that described by 

 Saussure ( Voyages dans les Alpes, ed. 4. t. i. p. 309), at the Lac de Joux. 

 This little lake, in the Jura, receives the water of the larger lake of Rouss, 

 and of several rivulets, without its having any other outlet, on account of 

 its being situate in a valley surrounded by heights, than by the numerous 

 crevices between the nearly vertical strata of limestone. On the north-west 

 side, tlie lake has made for itself a way to them, and has formed a deep hol- 

 low, by the bottom of which the water is soon absorbed- The inhabitants of 

 the valley have also formed similar outlets. As it is very important for 

 them that the water maintain a nearly uniform level, they lead the lake, 

 when it overflows, into little reservoirs, which they have dug down to the 

 limestone rock, and are eight or ten feet broad, by fifteen to twenty deep, 

 and which they carefully clear from the mud which collects in it. One could 

 hardly have believed that these reservoirs, or, as they are called there, fun- 

 nels {entonnoirs), both natural and artificial, gave rise to the springs of Orbe, 

 lying 680 feet lower, and three-fourths of a league from the north end of the 

 lake, if an accidental occurrence, in the year ITTfi, had not set it beyond a 

 doubt. At that time, the inhabitants, in order to lay dry the little lake, and 

 to clear out its outlets by the entoimoirs, dammed up the lake of Rouss, 

 which empties into it ; but this lake became at one time so much swollen, that 

 it burst the embankment, and rushed downwards with great violence into 

 the lesser one, which by that means became very turbid. The consequence 

 of this was, that the usually pure spring of Orbe became shortly after dirty 

 and impure. Yet the connexion of the lake of Joux with the springs of 

 Orbe seems to have been suspected from a very early period, as the stream 

 which connects the two lakes above has also the name of Orbe; therefore it 

 has been clearly marked for a portion of the river which discharges itself into 

 the lake of Neufchatel. 



