874 ANNUAL OF SCIENTIFIC DISCOVERY. 



barnyard, affirmed that we should soon have rain, as the water was 

 flowing in the aqueduct the spring having risen several inches. The 

 prediction was verified, for within two or three days, rain fell to a 

 considerable depth. In a short time the spring again sank low, and 

 ceased to supply the aqueduct ; but one cloudless morning, when 

 there were no visible indications of rain, its waters once more rose 

 flowing through the entire length of the aqueduct and, ere twenty- 

 four hours had elapsed, another rain was pouring down upon the 

 hills. On inquiry, it was ascertained from the residents in the vicin- 

 ity that the phenomenon was one of ordinary occurrence, and that, 

 for the last twenty years, the approach of rain was expected to be indi- 

 cated by the rising of the spring. 



Interested by these facts, I sought for others of the like nature, and 

 requested through the public prints information upon this subject 

 from all who happened to possess it, and also upon collateral points 

 which were conceived to have important relation to this phenomenon. 

 I was rewarded by the knowledge of only one additional instance, 

 existing in Concord, Massachusetts, where a spring that supplies a 

 certain brook, is said to rise perceptibly before a storm. 



The cause of this phenomenon has been attributed, by some, to the 

 fall of rain at the distant sources of the spring, a short time previous 

 to its descent in the vicinity of the spring itself; but this view is 

 doubtless erroneous, since it is altogether improbable that rain should 

 fall at two distant localities, year after year, with the same constant 

 period of time between them, and that this interval should be such as 

 to ensure that water falling at the first locality, should always arrive 

 through subterraneous channels at the second, before the rain there 

 commenced. 



I have not been able to ascertain the state of the barometer, either 

 at Rutland or at Concord, at the times when the phenomenon in ques- 

 tion occurs ; nevertheless, I believe the true solution will be found in 

 the diminished atmospheric pressure, which exists before a rain. 



The waters of a spring remain at any given level, because the at- 

 mospheric and hydrostatic pressure combined, exactly counterbalance 

 the upward force of the jet. The spring will, therefore, rise either 

 when the force of the jet is increased, while the atmospheric pressure 

 continues the same, or when the latter is diminished, while the former 

 remains constant ; and the elevation is greatest of all when the decrease 

 in the density of the atmosphere occurs simultaneously with an in- 

 crease in the strength of the jet. 



The rising of the water in the instances related, cannot, I think, 

 in view of the facts detailed, be fairly attributed to any sudden aug- 

 mentation of force in the current of the springs, but is to be regarded 

 as the result of diminished atmospheric pressure occurring at the par- 

 ticular times, in perfect accordance with known meteorological laws. 

 I am not aware that it has yet been ascertained whether this phenom- 

 enon is local or general. If the latter should be found true, and the 

 explanation given correct, we arrive at the curious discoveries that 

 the springs and fountains of the earth are natural barometers, whose 



