272 Report of thr Special Committee. 



In making these experiments, several things interesting to the 

 practical plowman were very fully exemplified: 



1. The unequal tenacity of the soil. The plowing was round 

 a centre back furrow. As the land grew wider the furrows, of 

 course, receded farther from each other. While testing the sod 

 and subsoil plow (seventy-second to eighty-third experiments), 

 one of the furrows ran for half its length through a sandy soil, 

 while the other ran through a moist, tenacious loam. The even 

 numbers of the experiments mark the sandy furrows; the odd 

 numbers the tenacious loams. The average draught of the loamy 

 furrows is 102 pounds greater than the sandy furrows. 



2. The im.poiiance of a proper adjustment of the several parts of 

 the plow. The draught as indicated in all the tables given above 

 is much heavier than it would have been if one uniform depth 

 and width of furrow had been adhered to throughout. The 

 change from one sized furrow to another, of course, involved a 

 change in the adjustment of the plow, and this was not always 

 ascertained on the first or even on the second trial. When this 

 was not accurately done, the plowman exerted his strength at the 

 end of a long lever to counteract the effect of the maladjustment, 

 which was at once indicated by the index of the dynamometer, 

 sometimes to the extent of 150 pounds. Some of the experiments 

 were made by plowing two furrows, or once around; others by 

 four furrows, or twice around. In most cases the two last furrows 

 showed less draught than the two first, because the plow swam 

 more freely and required less interposition on the part of the 

 plowman. As examples of this, we refer to the forty-tifih and 

 forty-sixth experiments, showing an averaged draught of 457 

 pounds, and the two next furrows of the same size, which only 

 averaged 426 pounds, showing an advantage of draught amount- 

 ing to 31 pounds, arising from more perfect adjustment. In those 

 last furrows the plow ran for more than two-thirds of the distance 

 by itself, without a touch of the plowman's finger, and for the 

 remaining third his touch was the lightest possible. The same 

 thing is shown by a comparison of the sixty-second and sixty- 

 third with the sixty-fourth and sixty-fifth experiments, the latter 

 being 35 pounds lighter than the former, for the same reason. 

 The necessity of accurate adjustment was very clearly illustrated 

 in the action of plow No. Q^. We desired to adjust it for a 

 furrow 12 inches deep and 1(3 inches Avide, but Mr. Brooks, 

 though perfectly acquainted with the inq)l(Mni'nt, was utterly 



