Supplementary Plow Trials. 



275 



Table shoiving the average depth and width of furrow, the average draught, 

 the average size of prism, and the average of the ivhole. 



[a) We learn from this table that, with prisms varying very 

 much in size, the largest being nearly two and one half times 

 greater than the smallest, the power required for cutting and 

 turning a lap furrow is expressed by 6.10 pounds for each sec- 

 tional square inch of the furrow slice. 



[b) We learn also that large furrow slices are turned with 

 more economy of power than smaller ones. The average power 

 required to turn the two smaller furrow slices of 79.19 square inches 

 was 6.66 pounds per square inch, while the power required to 

 turn the two larger ones of 139.66 square inches was 5.55 pounds, 

 or the smaller required 1.11 pounds more power than the former. 

 This result appears less favorably when considered with reference 

 to the average depth of the furrows than it does in relation to the 

 square inches. The two shallowest furrows average 6.35 inches in 

 depth, and require 80.94 pounds for each inch of depth. The 

 two deepest furrows average 9.72 inches in depth, and require 

 80.24 pounds for each inch of depth. 



[c) The sod and subsoil plow seems to require more power 

 than it does when it is worked with a coulter. Considered with 

 reference to the sectional area of the slice, the sod and sul)SoiI 

 requires 6.50 pounds of power for each square inch, while it only 

 requires 4.69 pounds per square inch when used with the coulter. 

 Considered with reference to the depth, each inch of the sod and 

 subsoil requires 78.00 pounds of power, while with the coulter it 

 requires 83.50 pounds, showing a greater expense of power in the 

 sod and subsoil plow of 1.81 pounds for each square inch of sec- 

 tional area, and 5.50 pounds less power for each inch in depth. 



