PRACTICAL EXERCISES 245 



EXPERIMENT 17 



Influence of One Inch of Rainfall on Height of Ground 

 Water- Table 



1. See that faucets are closed and that water in gauges 

 stands not much over 6 inches above the level of faucets. 



2. Measure and record height of water in gauges. 



3. Determine the cross section of tank. It will ap- 

 proximate 60 inches by 15 inches. 



4. Introduce into the tank an amount of water that 

 equals one inch over the cross section of the tank. This 

 will be approximately 900 cubic inches of water. 



5. After water has come to constant height in all the 

 gauges, measure and record height of water in each gauge. 



6. With the data thus obtained, determine the influ- 

 ence of an inch of rainfall upon the height of ground water- 

 table in this particular soil. 



EXPERIMENT 18 

 Percentage of Pore Space 



With the data obtained in Experiment 17, determine the 

 percentage of pore space in the soil in the tank. 



PRACTICAL EXERCISES 



In addition to the laboratory exercises outlined above, 

 the student should be made familiar, by practice, with the 

 several operations involved in the use of the level, laying 

 out of drains, and, when possible, with the actual work of 

 digging drains and laying tile. These operations may be 

 grouped something as follows : 



