of I' 



245 



306. Influence of Difference of Soil Moisture on the Draft 

 of Plows.^ By combining the data in the two tables of (304) 

 with reference to the degree of moisture in the soil Avhen 

 the trials were made we have the results given below. 



From this comparison it is clear that the draft of the 

 plow is very much modified by the condition of the soil. 

 The results show the draft more than doubled when the 

 soil was clrver. 



FIG. 79. Type of moldlx.iird suited to mellow soils requiring little pul- 

 verizing. 



307. The Draft of Sulky Plows. It is generally claimed 

 that the draft of sulky pl.\vs is less than that of the free- 

 swimming types because the friction of the sole and land- 

 side is transferred to the well oiled bearings of the carriage. 

 The few records accessible do not show a material gain, 

 when the influence of the weight of the carriage and driver 

 are not deducted, but where the draft is no greater on the 

 team with the man riding than when walking, and the plow 

 16 



