THE MODERN BATHROOM 



149 



Snr\ /*' SETS 



adds much pleasure to the daily life. A little knowledge of 

 a few scientific principles underlying the operation of these 

 fixtures will be useful for us to have and may save much ex- 

 pense and trouble. We have already studied different types 

 of faucets, and know how to make simple repairs on them. 



Experiment. To see how the siphon works. 



Materials: Battery jar. Glass beaker. Rubber tube. Glass tube. 



Pulley with little friction. Cord or rope to go over the pulley. 

 Method: (A) Hang a short heavy cord or small rope over the easily 



running pulley with the two ends at the same level. See figure (a). 



Result ? Change the cord 



so that one end hangs 6 



inches or more lower than 



the other side. See figure 



(b). Result? (B) Con- 

 nect a six-inch length of 



glass tubing to one end of 



the rubber tube. Fill the 



entire glass and rubber 



tube with water. Hold 



the finger over the end of 



the glass and put the end 



of the rubber tube into a 



jar of water. Hold the 



end of the glass tube just 



below the level of the 



water in the jar, and open 



it. Carefully raise the 



tube until the end is just 



level with the water sur- 

 face in the jar. See figure (c). Does water run out? Does it run 



back? Give reason. Lower the end of the glass tube so that it is 



several inches below the level of the water in the jar to (d) in figure. 



Result ? Explain. What will happen if it is raised above the level of 



water in the jar? Try it. 

 Conclusion: The tube is used in this experiment as a siphon. Explain 



how much of the action of the siphon depends on the pressure of the 



atmosphere. How does the analogy with the rope help to explain a 



part of the action of the siphon ? 



