8 

 PRACTICE 3 



Effects of Drainage on Temperature of a Soil.* 



Two wooden trays 3 by 4 feet and six inches deep, one lined with 

 zinc to prevent the loss of water and the other made so as to allow 

 drainage, are filled with the same kind of soil. Water is added to each 

 till drainage begins in the latter. After three or four days the tem- 

 perature of each at 1, 2, and 4 inches in depth is determined hourly 

 on a clear day. 



Explain differences in temperature. 



Why is clay land liable to be cold? 



"This and the following Practice logically come later in the course, but the season 

 here makes it necessary to give it early in either semester. Better results may be ob- 

 tained by conducting these experiments before the weather gets too cold in the fall or too 

 hot in the spring. 



