Supplementary Plow Trials. 283 



Experiment jSfo. 114 — No. (59 was furnished with a coulter and 

 a stubble mould-board, the furrow being nine inches deep and 

 twelve inches wide. The draught of the plow, thus adjusted, was 

 729 pounds. 



Experiment JSFo. 115. — The coulter was then withdrawn from 

 the plow, and a skim plow was placed on the beam and set to 

 work with a furrow of the same size; draught, 659 pounds, show- 

 ing a difference of 70 pounds in favor of the skim plow. These 

 experiments are believed to give a sufficient answer to the question. 



VII. What is the elasticity of different soils ? 



We did not try this experiment as fully as it deserves, as we 

 found it would require more time and expense to do so than we 

 could well afford; but we performed it carefully in different parts 

 of the same field, which differed considerably in consistency. 



Experiment No. 116. — Eeferring to the report of the judges of 

 the Utica trial for the method of making it, we have to state that, 

 with a furrow eleven inches deep and sixteen inches broad, the 

 upper part of the slice in the most tenacious part of the field 

 would stretch seven and a half inches beyond the lower portion 

 before breaking; in the least tenacious part it would stretch tour 

 and three-quarter inches; and soils of intermediate tenacity would 

 stretch in proportion. 



Experiment No. 117. — The stretch diminished according to the 

 shallowness of the furrow slice. At four inches deep it would 

 not stretch much more than an inch in the toughest part of the 

 field, and in the loosest part it would not much exceed half an 

 inch. At six inches deep it stretched two and a half inches, and 

 at eight inches deep, a little over three inches. 



This great difterence in the elasticity of soils shows how impos- 

 sible it is to make any one plow which shall work equally well in 

 all soils. If it has a sufficient twist to break the least tenacious 

 soils, it will utterly fail to disintegrate those which are more 

 tenacious. If, on the other hand, it has enough sharpness of twist 

 to disintegrate the most tenacious soils, it will cause a great waste 

 of power when used in less tenacious soils. All that can be 

 reasonably asked of a plowmaker is that, a soil and depth of 

 furrow being given, he shall make a plow which will disintegrate 

 it most thoroughly with the least expenditure of power. It by 

 no means follows that it will be the best plow in any other 

 soil? 



