Nevu application of the Syphon. 547 



III. 



New Application of the Syphon it raift Water above the Surface of the Refertrolr. In a Letter 



from Mr, William Close. 



To Mr. NICHOLSON. 

 SIR, 



J. HE fyphon will raifc a ftream of water through an extenfive fpace in every fituation 

 where a little defcent can be procured, but while the operation continues, no water can be 

 taken diredly out of the ftream above the loweft part of the tube. When, however, the 

 two open ends of a fyphon are clofed, a quantity of water may be let out of the higheft 

 part, and its place fupplied by introducing a like quantity of no ufe : all the avenues for 

 the purpofe being then clofed, and the ftream fuffered to flow through the tube; the 

 ufelefs water will be difplaced, and a frcfli quantity niay be foon after drawn off. This 

 mode of exchange may be ufeful in furnifliing a fupply for waftiing, and fome other pur- 

 pofes, but there are fevetal domeftic ufes for which the water drawn off will not be thought 

 fufficiently pure. A method of taking water out of the fyphon at any height within the 

 limits of the elevation, without retarding the ftream, or introducing another quantity, has 

 often appeared to me very defirable, and fome months ago, I made a number of experi- 

 ments to determine the pra£licability of the projeft. 



My hopes of fuccefs were founded upon the following obfervatlons : 



When water flows through a fyphon that has an elbow or dilatation containing air, the 

 ftream moves much flower, and is fmaller on entering into the external air, than when the 

 part is completely filled with water. When the current moves with a certain velocity, its 

 lateral aftion extrafts the air, and carries it down t^e defcending column. As the part 

 fills with water, the ftream becomes fuller, and its velocity encreafes. 



Among a variety of projects for extrafting the air out of a veflel fixed to the fide of a 

 fyphon, and filling it with water,- by the afllftance of the lateral aftion of the ftream, the 

 following feemed the moft likely : 



If the connexion between the veffel and fyphon be made by two tubes, the end of one 

 turned againft the current, and the end of the other turned from it, the ftream after ftriking 

 the end of the firft tube, will be contracted until it has pafled by the end of the fecond. 

 "After this it will begin to expand ; the air will be drawn out of the velTel through the tube 

 turned from the current, and water will enter by the other, until the vefTel is filled; the 

 ftream beyond the contraction occafioned by the two tubes will then receive a fupply 

 through the veflel. 



The refult of an experiment founded upon this theory was very fatisfaCtory. In place, 

 however, of a particular account of the firft experiment, I fliall give a detail of fome 

 others, in which a ftill more eafy expedient was adopted, to produce the fame efl"e6t : 



4A2 Two 



