93 



to require the agency of a siphon to account for its operations. The 

 characters as ascribed to Pliny's Well, and the well iu Dodona, are 

 very ambiguous and unsatisfactory; but the operations of the three 

 remaining springs, and more especially the register of Giggleswick 

 Well, perplex the hypothesis of a siphon with insuperable difficul- 

 ties j which a superficial inspection of the table will discover to the 

 reader. 



The theory, which I shall now propose for the explanation of 

 irregular reciprocating springs, was suggested by an accidental ob. 

 servation; which occurred to Mr. Swainston, whom I have men- 

 tioned above. Tiii.s gentleman, who is a manufacturer of Morocco- 

 leather, has a contrivance in his works, for the purpose of filling a 

 boiler of a particular construction with water. This apparatus 

 consists of a tub, which is considerably elevated above the boiler. 

 The water is conveyed from a pump along a trough into this vessel ; 

 from which it runs immediately into the upper extremity of an in- 

 verted siphon, which is cemented into a hole in the bottom. This 

 compound tube consists of three branches or legs $ the first 

 descends perpendicularly beneath the tub, and is the longest of the 

 three ; the second ascends again artd carries the water, which comes 

 into it from the first, to a convenient heilit above the brim of the 

 boiler; the third is a descending leg, which performs the office of 

 uozle, that is, it discharges the water from this crooked canal into tiie 

 boiler. Mr. Swainston observe i by accident, that when the work- 

 men were filling the vessel last-mentioned, the water reciprocated in 

 the tub, the surface of it rising and falling alternately in a manner 

 which he could not explain, by supposing some slight irregularity in 

 the management of the pump. When the appearance was more 

 carefully examined, he found a corresponding variation in the etflux 

 at the nozle; for when the water was rising in the tub, the stream 

 was perceptibly wraker at this outlet, than it was during the ebb or 

 fall of the water in the vessel last-mentioned. He farther observed, 

 that when the water in the boiler rose high enough to cover the end 

 or nozle of the siphon, bubbles of air were seen ascending from this 

 orifice, during the ebb in the tub, or at least duri:^ the former part 

 of it; but that they did not appear during the flow, or whilst the 

 water was accumulating in the tub. The fluctuations here described,, 

 were far from being regular, either in magnitude or duration; for the 

 water rose much higher in the tub at one time, than it did at 



