8o 



WATER IN THE HOME 



water is delivered directly to his home through pipes. The 

 problem of city water supply will be taken up later. It is 

 sometimes quite easy for the country house to have running 

 water simply because water is pulled down by gravity, or 

 " runs down hill." If the spring or source from which the 

 water is taken is above the height of the house, it can be 

 piped into the house easily ; if the well or spring is below 

 the house we have a different problem. 



If the country boy or girl acquires a little knowledge of 

 air pressure, it might enable him or her to plan how to 



make use of this knowledge to 

 deliver water into the house. 

 We have already seen that air 

 has weight. If you take a 

 tumbler of water, place a 

 smooth card over the tumbler 

 and then invert it carefully, 

 you can lift the glass upside 

 down with the water in it. 

 A moment's thought will tell 

 you that something is pressing 

 upward on the card, or that 

 the air pressing against the 

 card weighs more than the 

 water held in the glass. If you take a wide-mouthed bottle, 

 fill it with water, insert a cork containing a glass tube, and 

 then try to suck the water out you will be unable to do so. 

 Loosen the cork a little and then try, and you will find that 

 you can suck the water out. We may demonstrate this 

 same principle in another way. 



Experiment. To show how air pressure can lift water. 



Materials: A U-tube, piston, and stopper to fit, a glass tube. 



The water is held in the glass by the 

 upward pressure of the air. 



