FARM MECHANICS. 



161 



necessary for the team, walking at the same rate, and 

 working the same number of hours daily ? 



558. A stubble plow is used with and without the coul- 

 ter. The total draft with the coulter was 300 pounds ; 

 without it 410 pounds. A two-horse team walking at the 

 rate of 2.5 miles an hour for 10 hours daily pulled the 

 plow with ease when the coulter was used. But a third 

 horse was necessary without it. What was the minimum 

 allowable weight of the third horse ? 



Draft of furrows. The following tests were made 

 where the soil was a clay loam and shortly before had 

 been sod. 



DRAFT OF DISK HARROW. 



559. How many pounds draft are added to the pull 

 of a disk harrow up grade when the driver rides ? What 

 is the percentage of increase? 



560. What is the difference in draft of the disk har- 

 row, set at full angle, when operated up and down 

 hill? What is the percentage greater when operated up 

 grade ? 



561. How many per cent greater is the draft of a disk 

 harrow operated down grade when the driver rides than 

 when he walks? 



562. When operated on level ground? 



