SPRINGS, RIVERS, CANALS, LAKES, 



from the siphon, which grows gradually weaker, the surface of the 

 well will cease to rise so soon as these opposite powers are equal in 

 their effects; and the flow will be at the full in this instant. 4th. 

 The well cannot remain stationary, for any length of time, at its 

 highest elevation ; because the vigor of the sip'ion being perpetu- 

 ally on the decline, all the water discharged by it will run off 

 through the outlet, together with part of that, which had been pre- 

 viously accumulated in the visible fountain, during the time of the 

 flow. 5th. Hence it is evident that the well will begin to subside, 

 the moment it becomes stationary; after which it will persevere in 

 a retrograde motion, until the siphon shall have emptied the sub. 

 terranean reservoir. 6th. If no veins of water discharge themselves 

 into the visible basin, besides the siphon which runs periodically, 

 the spring is called an intermitting fountain. The Bolderborn is of 

 this kind, for it remains dry while the secret reservoir is filling, and 

 flows while the siphon is in action. 7th. But if the spring receives 

 other supplies in addition to the intermitting current, it is called a 

 reciprocating fountain ; because the stream that issues from the 

 outlet of the visible basin is permanent, though it varies in quantity; 

 on this account the well ebbs and flows alternately, but never runs 

 itself dry. All the fountains, which will b<> mentioned in the sequel 

 are of this kind ; and Pliny's well, near Coma, appears to possess 

 the same character from his description of it. 8th. The fluctuations 

 of an ebbing and flowing well, which is fed by a siphon, will remain 

 invariable, so long as the stream, that falls into the subterranean 

 reservoir continues to be uniform. But these external and visible 

 operations of the well, are so far under the influence of the current 

 last mentioned, that they will evidently suffer a temporary suspen- 

 sion, so often as the influx into the concealed cistern, amounts to a 

 certain quantity in a certain time; for the siphon is but a second. 

 ary agent in producing the phenomena of reciprocation, its business 

 being to empty the subterranean basin, so often as it is replenished. 

 JSIow the time of filling this magazine of water will be the shortest, 

 when the influx into it is most abundant, and the contrary ; conse- 

 quently an increased discharge into the subterranean reservoir, will 

 diminish the intervals of the siphon's inactivity, and prolong the 

 periods of its action. It follows, from these premises, that when 

 the influx becomes equal to the feeblest effort of the siphon, the 

 quantity of water thrown into the concealed basin, will exactly 



