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Popular Science MontJih/ 



Experimenting with the Siphon 



ASlMPLY-constructcd siphon offers 

 a most fertile field for amateur ex- 

 perimentation. In some cases water can 

 be made to How straight up twenty feet 

 into the air until it passes the curve in 



Two tumblers, one higher than 

 the other, joined by glass tub- 

 ing, can be used to demon- 

 strate the siphon principle 



The water will easily flow to a 

 height of six feet with the 

 apparatus shown at the right 



the siphon and Hows down 

 again. 



To carry on a series of ex- 

 periments all the apparatus 

 needed is a piece of glass- 

 tubing and a connected piece 

 of rubber-tubing. The glass 

 tube may be bent in an 

 alcohol flame, and a siphon so 

 constructed that it will take 

 water upward for six feet or 

 more, and then downward in 

 the other arm. If the joints are made 

 tight the water will How even higher. 

 VVhen the water has passed from one 

 vessel into the other, the lower vessel 

 may be raised, and back the water will 

 flow, thus running uphill and down- 

 hill. The only difficulty in this experi- 

 ment, aside from making the joints 

 light, is to fill the pipe at the start. 

 This may be done by filling the entire 

 pi|)e when the parts arc all on the same 

 level. The ends may then be stoppetl 

 and the one end raised into a perpcn- 

 dii ular position. 



Hill with all siphons of this kind the 

 tr()ui)le is to establish a permanent con- 

 duit between the two receptacles, since 

 the siphon will exhaust itself unless the 



higher vessel is always kept filled. A 

 siphon will not wait for a fresh supply of 

 water, but will empty itself and cease 

 to act. 



Recently one experimenter was 

 obliged to devise a means whereby the 

 siphon would hold its contents and wait 

 for a fresh supply. This was accom- 

 plished by turning up one or both ends of 

 the siphon. By this method a series of 

 aquaria was connected so that water 

 would run through the tubing and wait 

 for a supply ; that is, a tiny stream would 

 keep the supply to the siphon running 

 continuously, and the siphon would hold 

 the water running at a permanent height. 

 Theoretically it is the push and not 

 the pull that causes the water to run. 

 The pressure of the air on the surface of 

 the water in the upper vessel 

 pushes the water up to take 

 the place of what would be a 

 vacuum. The action is simi- 

 lar to the pull on the part of 

 two pulleys, in which one is 

 heavier than the other. It is 

 evident that the hea\ier 

 weight pulls up the lighter. 

 So it is with the siphon. The 

 curved angle of the siphon 

 takes the place of the pulley, 

 and the long arm full of water 

 takes the place of the heavier 

 weight. Once the long arm 

 full of water starts it "pulls" 

 the contents of the shorter 

 arm. 



How the glass tubing is arranged when 

 two largo jars of water arc to be siphoned. 

 The test may be carried on indefinitely 

 by reversing the position of the tubes 



