178 Report on Trials of Plows. 



draught of the four swing plows was 245 pounds; that of the four 

 wheel plows was 210 pounds, showing an average of 35 pounds 

 in favor of the wheel plows. In a blue clay soil the average 

 draught of the four swing plows was 686 pounds; the average 

 draught of the four Avheel plows was 630 pounds, showing a differ- 

 ence in favor of the wheel plows of 56 pounds. In a sandy loam 

 the difference in favor of the wheel plows was 49 pounds. The 

 average difierence in these four trials, in as many different soils, 

 was 37 pounds, or 10 per cent, in favor of the wheel plows. 



Mr. Handley accounts for this superiority of wheel plows as 

 follows: 



" As regards the cause of the diminished force required by the 

 wheel, compared with the swing plow, it appears to me to be 

 principally, if not fully, explained by the more uniform horizontal 

 motion communicated to the share and sole of the former through 

 the regulating medium of the wheels at the fore part of the 

 beam, which diminish the shocks arising from the continued 

 vibrations of the implement when balanced between the hand of 

 the plowman and the back and shoulders of the horse. It is not 

 contended that Avheels so situated act the part of lessening the 

 friction between the sole and the soil; but they keep the rubbing 

 part more truly to its depth, and maintain its horizontal action 

 more correctly; whereas the horses affect a swing plow at every 

 step by the irregularity of their proper movement, which has to 

 be counteracted by the effort of the man at the opposite end. 

 Thus conflicting forces are momentarily produced, and continual 

 elevations and depressions of the point of the share take place, 

 together with deviations from the flat position of the sole, which 

 should be retained at right angles to the perpendicular; and to 

 remedy which unskillful plowmen bear unequally on the stilts, 

 which produces a lateral pressure landwards, and consequently a 

 great amount of friction along the whole of the left side plane of 

 the plow. However small may be the eflbrts of the plowman to 

 keep his plow ^ sivim.ming fair,^ those efforts must be attended 

 ivith increased resistance, and consequently with increased resist- 

 ance to the horses." 



It is not pretended that, in a wheel plow, none of these irregu- 

 larities of motion exist; on the contrary, the dynamometer shows 

 them to be very considerable, but less in degree than in the swing 

 plow. The oscillations of the index of the dynamometer are, as 



