ajid Spuutwg Fountains. 281 



of a projecting fountain, except in so far as it may dirlate the 

 bulk of the water ; and in this dilatation, the air would gradually 

 lose a portion of its compressing power, and by this the velocity 

 of the flow of the fountains would be diminished. The sup- 

 porters of this hypothesis assert indeed, that there is always 

 running into these subterranean reservoirs, a quantity of water 

 sufficient to maintain matters just as they were, and in such a 

 condition, that this compressing air is never allowed to dilate 

 itself to an extent that will be apparent ; but we may inquire 

 if they have ever remarked that these fancied columns of com- 

 pressed water could not play the part attributed them, except 

 at the moment when the pressure they should exercise would 

 overcome the elasticity of the confined air ? and at this moment 

 would it not be the overflowing liquid column which would in 

 reality propel the water in the ascending pipe ? We may also 

 inquire why a power which can produce such an effect at one 

 moment, cannot do it for a continuance ? 



It is true that, in many machines, and in gasometers, and 

 likewise in those wheels which are known under the name of 

 fly-wheels, there are means devised for regulating irregular ve- 

 locities; but were these considered as isolating moving powers, 

 they would never exhibit any thing like the regularity that is 

 observed in the flow of these wells and fountains. 



We shall at present pass by other objections not less serious, 

 which might be made against this theory, grounded upon the 

 action of compressed air in these watery deposits, to examine, in 

 a very few words, another very odd hypothesis, which has ne-^ 

 vertheless been very popular for some time. 



It being conceded, that the sheet of water into which the pit 

 is sunk, is always included between two impermeable strata, it 

 has been maintained that the upper of these strata, being cbarged 

 with the weight of all the superincumbent beds, must thereby be 

 bent downwards, and so must press the fluid on which it rests 

 in the same direction, which would consequently dispose the 

 water to rise, and be the true cause of its ascension. 



Let this pretended pressure and bending be, for a moment 

 admitted ; then three distinct contingencies will present them- 

 selves for consideration; either the yielding stratum will be 

 steadily moving from above downwards, till it come in contact 



