28 LABORATORY LESSONS IN GENERAL SCIENCE 



the well is on higher ground? What special dangers are 

 there in the use of well water in towns? 



4. Describe somewhat in detail the construction of 

 cisterns. What difficulties are experienced in providing for 

 a water supply by storage in cisterns? What advantages 

 are there in the use of cistern water rather than well water V 

 State objections to its use for drinking and cooking. Aside 

 from the possibility of disease germs in it, why may drink- 

 ing cistern water cause sickness? 



5. By use of a diagram show the construction of a 

 cistern having a filtering wall of porous brick, and indicate 

 suitable places of inlet and outlet for the water. What 

 precautions should be taken to keep cistern waters free 

 from dust and from organic matter? What difficulties 

 are there in filtering rainwater as it goes into the cistern? 

 What conditions in a city usually make the use of cisterns 

 impossible ? 



6. Describe the action of the "chain pump " as a means 

 for aerating cistern waters. Explain the nature of the 

 chemical change thus accomplished in the water. Account 

 for the odor and taste of cistern water. 



7. Tell something about an air-pressure system for 

 supplying water to all parts of a house from a cistern. 



8. State the source of the water supply of your city. 

 Describe the manner of its storage and distribution. What 

 is the cost of water to a consumer? What protection has 

 this water supply from contamination? What means are 

 employed, if any, for its purification? 



9. What danger is there in the use of water from streams ? 

 What advantages may there be ? What is generally true of 



