Figure 3. — The left tank has been filled with sand. 

 The small and large "voids" can be seen in the right 

 tank. Manometers are mounted on the front of each 

 tank. Plugs in the sides of tanks provide access for 

 obtaining density and moisture samples. 



Figure 4. — An "I" beam, supported by steel "A" 

 frames, serves as a track for a hoist used to lift tanks 

 for weighing. Each tank was weighed while dry, after 

 each change in water level, and at saturation. 



coarse sand, 99 percent passed a #16 Tyler 

 screen (1.00 mm.) and not more than 1.47 per- 

 cent passed a #32 Tyler screen (0.500 mm.). Of 

 the fine sand, 99 percent passed a #32 Tyler 

 screen and only 18.73 percent passed a #60 

 Tyler screen (0.250 mm.) Before the tanks 

 were filled vfith sand, the access tubes were cen- 

 tered in the tanks. Coarse sand was released 

 from an overhead hopper through a hose in 

 such a way that the particles had a constant fall 

 distance and constant initial velocity to assure a 

 constant bulk density.' When the level of sand 

 in the tank reached 18 inches above the bot- 

 tom, the large 6-inch-diameter void tube was 

 slipped down over the access tube and allowed 

 to rest on the sand. Pouring was resumed until 



' Unpublished data in files of the Forestry Sciences 

 Laboratory, Logan, Utah. 



there were 13-1/2 inches of sand over the top of 

 the large void. Then the small 3-inch diameter 

 void was slipped onto the access tube and filling 

 v\ath sand continued until there were 14 inches 

 of sand over the small void and the sand was 2 

 inches from the top of the tank. This procedure 

 was used to fill both tanks; however, in the 

 control tank the test voids were filled wdth sand 

 before the top of the void was attached. The 

 only difference between the two tanks was that 

 the test (sample) tank had empty voids and the 

 control tank had voids filled with sand. 



The tanks were positioned under the pipe 

 frame and weighed (fig. 4) to determine the dry 

 weight of sand in each tank. A hose was at- 

 tached to the drain on the bottom of each tank 

 and the tank was slowly filled with water from 

 the bottom. It was then drained and refilled to 

 remove all air from the sand. Each tank was 

 reweighed when filled so that the total weight 

 of water in the sand could be calculated. 



4 



