CAPILLAR Y MOVEMENT OF SOIL MOISTURE. 13 



having a screw thread and nut for tightening. The joint between 

 the glass and the-box --is made with a strip of maltoid roofing. The 

 present box gives good satisfaction and is sufficiently rigid to admit 

 of considerable handling without danger of cracking the soil column. 



SOIL SAMPLING EQUIPMENT. 



The soil samples are taken with a carpenter's bit, the shank of 

 which has been lengthened to 16 inches. The soil samples are placed 

 in 4-ounce glass bottles fitted with aluminum screw caps. They are 

 dried in the usual double- walled water- jacketed oven. The oven used 

 is of local make and of galvanized iron. The inner oven is 12 by 12 

 inches, fitted with one shelf. 



EVAPORATION TANK. 



The evaporation tank is made of galvanized iron, and is 18 inches 

 square and 12 inches deep. The tank is set in a wooden box 2 inches 

 larger all around than the tank. This space is filled with soil, thus 

 insulating the tank upon the bottom and sides. 



AIR TEMPERATURES. 



The air temperatures are taken with a self-recording thermograph. 

 The instrument is set up immediately adjacent to the flumes and is 

 shaded and protected from storm. 



ADDITIONAL EQUIPMENT. 



A variety of special equipment has been used, and this will be de- 

 scribed with the presentation of the data obtained by its use. 



KATE AND EXTENT OF MOVEMENT OF SOIL MOISTURE BY 



CAPILLARITY. 



There are so many factors controlling the rate and extent of move- 

 ment of capillary moisture (4) (11) that it is very difficult to apply 

 the data obtained from one soil to a different soil even of the same 

 type. Without knowing more of the effects of those different factors 

 upon the movement of soil moisture it is not possible to make such 

 comparison and expect accurate quantitative results, even though we 

 have a complete chemical and mechanical analysis of the two soils 

 (8) (15). Within each soil are those influencing factors, such as 

 soluble mineral salts, the organic material, the colloids, and many 

 others, which influence in various and irregular ways the movement 

 of soil moisture by capillarity. Certain other factors, such as the 

 meteorological conditions that may be controlled to a large extent, 

 exert a material influence upon the movement of soil moisture by 

 capillarity. 



