sand was +36 percent moisture by volume. 

 Then, figure 14 is entered at 36 percent and 

 foUowed vertically to the error curve for the 

 coarse material. Move horizontally from this 

 intersection to the negative error curve for the 

 coarse material; from this point, the estimated 

 maximum negative error of -6.5 percent mois- 

 ture by volume can be found on the abscissa. 

 Also, by continuing left horizontally from the 

 negative error curve to the ordinate, the esti- 

 mated volume of 62.50 cubic inches for the 

 void can be found. The estimated maximum 

 negative error is of interest because this value 

 may be difficult, if not impossible, to measure 

 in the field when the void is empty. It should 

 be kept in mind that figure 14 was derived 

 from laboratory data obtained from symmet- 

 rical voids. It is not known whether figure 14 

 will provide accurate estimates of the volume 

 of an asymmetric void. 



JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 

 DATE 



Figure 12. — Seasonal soil moisture for a given depth. 



5 10 15 20 25 30 35 40 45 50 55 60 +5 +10 +15 +20 



PERCENT MOISTURE BY VOLUME ERROR - % MOISTURE 



Figure 13. — Field data curve showing measiuement error caused by a void partly filled with water. 



17 



