Figures 9E and 9F show the continued in- 

 crease in the amount of negative error as the 

 water level is lowered within the small void. 

 When the void was empty, the maximum 

 measurement error was -3.0 percent by volume, 

 and the total measurement error was -0.25 

 inch, from 16 inches below the surface to 35 

 inches below the surface. 



Large Void-Fine Sand 



Fig\u-es lOA through lOF show the same 

 pattern of measurement-error change as the 



water level dropped within the large void. The 

 maximum positive error was +52.2 percent 

 moisture by volume with a maximum positive 

 total error for the large void of +4.27 inches of 

 water when the void was fully saturated. When 

 the void was empty, the maximum negative 

 error was -6.3 percent moisture by volume, and 

 a maximum negative total error for the void of 

 -0.50 inch of water. 



It is interesting to note that when the meas- 

 ured medium contained less than 1 percent 

 moisture, both curves are coincident and the 

 voids caused no error (fig. 11). 



30 - 

 35 - 

 CO 40 - 



Uj 

 Co 



^ 45 

 50 

 55 



3: 



CL 



60 







coA/r^OL r/iA//c less r^/i/v / % Afo/sru^e 

 S/iMPL£ r/l/V/C LSSS r^/iA/ / % Afo/sn//?£ 



J L 



_L 



-L 



10 



15 20 25 30 35 40 45 



PERCEHT MOISTURE BY VOLUME 



Figure 11. — When the measured medium contained less than 1 percent moisture, both moisture curves are 

 coincident and the void causes no error. 



13 



