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SUPPLEMENT. 



in the channel Ee F: and when it rises to the top of 

 that channel at e, it will run down the parte.FG, and 

 make a swell in the spring G, which will continue till 

 all the water is drawn off from the cavern B, by the 

 natural syphon EeF, (which carries off the water faster 

 from B, than the channel D brings water to it) and then 

 the swell will stop, and only the small channel C C will 

 carry water to the spring G, till the cavern B is filled 

 to B again by the rill D ; and then the water being at 

 the top e of the channel EeF, that channel will act 

 again as a syphon, and carry off all the water from B to 

 the spring G, and so make a swelling flow of water at 

 G as before. 



To illustrate this by a machine : Let A be a large 



T 



wooden box, filled with water ; and let a small pipe C C 

 (the upper end of which is fixed into the bottom of the 

 box) carry water from the box to G, where it will run 

 off constantly, like a small spring. Let another small 

 pipe D carry water from the same box to the box or 

 well B, from which let a syphon EeF proceed, and 

 join with the pipe C C at /': the bore of the syphon 

 being larger than the bore of the feeding-pipe D. As 

 the water from this pipe rises in the well B, it will also 

 rise as high in the syphon Ee F: and when the syphon 



