52 



Our Surroundings 



Experiment to Show the Principle of One Type of Water 

 Supply System by a Model Apparatus. Set on an iron ring 



stand a can having an outlet 

 in one side near the bottom. 

 Attach one end of a piece of 

 rubber tubing several feet long 

 to the outlet, allowing the tub- 

 ing to extend gradually down- 

 ward. Insert several thistle 

 tubes at intervals in the upper 

 side of the tubing at different 

 heights from the floor. Then, 



EXPLAIN How THIS ILLUSTRATES 

 A WATER SUPPLY SYSTEM 



from a jar below, pump water into the can. What becomes of 

 the water after it reaches the can ? What do each of the following 

 represent in a water system : the can, the jar, the pump, the tubing, 

 the thistle tubes? 



A LIFT PUMP 



When the piston is drawn up it removes most of the air from the tube. Atmospheric 



pressure forces up water to replace the air. Succeeding strokes continue to raise the 



water past the two valves until it flows out of the spout. 



Dangers From Faucet Filters. A faucet is a device fitted 

 with a valve in such a way as to control the outlet of a pipe carry- 

 ing a liquid. A filter is a device used for straining any undesir- 



