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valleys in the neighbourhood of Kissingen are composed, on the left 

 bank of the river Saal, whose course is marked for many miles by 

 the occurrence of mineral springs, and by the discharge of carbonic 

 acid gas. The author supposes its direction to be connected with 

 a line of fissure, and the gas to have its origin in the neighbouring 

 extinct volcanic focus of the Rhongebirge. 



The present spring was bored for in 1822, and the 4-inch shaft 

 was carried to a depth of 323 Bavarian feet from the surface ; but 

 at the top it expands into a well eight feet in diameter. At a 

 depth of 156 feet, the water ebbed for the first time, and it has 

 done so since with more or less regularity; but what is particularly 

 strange is, that this regularity appears to depend in a, not very con- 

 ceivable way upon the action of the pumps which are employed to 

 raise the brine from the shaft for the purpose of evaporation. 

 Whilst the pumping machinery works, the ebb and flow of the 

 spring are very regular ; when it stops, the regularity nearly ceases. 

 When the spring is in full flow, its appearance is very striking. 

 The great shaft of eight feet in diameter is filled with water, agi- 

 tated in the most violent manner by the torrents of gas which it 

 discharges. Whilst its turbulence is at a maximum, the gas abrupt- 

 ly ceases to flow, and in a few seconds the surface of the water in 

 the shaft is perfectly tranquil. The-water descends, and continues 

 to do so, at first rapidly, then more slowly, until it has subsided 

 nine or ten feet, which occurs in about fifteen minutes. This 

 point has been but just reached, or for a very short time, when 

 a sudden swelling up of the water first, and then of the gas, is 

 observed in the bottom ; the shaft fills very slowly, — the flow of 

 water and of gas continue for a long time progressively to increase, 

 not apparently attaining their maximum until the water is at its 

 full height, which requires from thirty to forty minutes after the 

 first return of the stream. It remains in a state of violent agita- 

 tion for two hours, or somewhat more, when the preceding cycle 

 of phenomena is repeated. This description applies to the ordinary 

 state of tlie spring, when five or six pumps are in action; if these 

 are fewer the periods are longer ; if more, the reverse. This Mr 

 Forbes clearly made out, from registers of observations frequently 

 verified by himself. Of the natural state of the spring, when no 

 pumps work, he had not the same means of satisfying himself. 

 There can be no doubt, however, that, in that case, the periods are 

 longer and more uncertain, those of flow amounting to three, four, 

 or five hours, and of ebb to one, two, or three. Several of the 



