158 



Journal of Agricultural Research voi.xii, No. 4 



From (17) 



From (33) and (34) 



K = 



A = 



— y— 1.78^ + 20 

 i.299)/+3- 31.35' 



From (18) 



From (19) 



From (36) and (37) 

 K 



- 15.73; + io.04y- 13.832+ 1 1.95 

 x-i.i77y- 2.282+51.45 ' 



1.584K + 6.335, 



B = 



B = 



K-7.29 



— %— .892}/ + i9.4 

 .619^+2-32.74 ' 



7.29^ + 2.58^-6.3352 + 65.85 

 x+. 0887-1.542 + 32.46 



(34) 



(35) 



(36) 



(37) 



(38) 



By eliminating K from equations (35) and (38) the following equation 

 for the surface of the plow bottom is obtained : 



3.9*2 +/ + 3.4522- 7.53:^/2- 7.28x2 + 6.79%)/ 



+ 87.i«+i2o.75>'- 75.052 + 227.25 = (9. 



(39) 



Table II is compiled for purposes of checking the values computed from 

 equation (39) with those obtained by measuring. 



Table II. — Values {in inches) for the surface of the plow bottom shown in Plate 6, A, 



obtained by measurement 



