No 6. DEPARTMENT OF AGRICULTURE. 995 



In all cases a run means a round trip— going and returning. 

 The tuUkS were made in the following order: 



Average draft. 



Kun 1. Narrow tire in original rut, 342.8 pounds. 



Run 2. Narrow tire in original rut, 331.7 " 



(Rut not perceptibly deepened.) 



Run 3. Broad tire on the narrow tire rut, 521.0 " 



Run 4. Broad tire on the narrow tire rut, 342.8 " 



Run 5. Broad tire on the narrow tire rut, 335 . " 



Run G. Broad tire on the narrow tire rut, 32G.5 " 



(Rut about 2 inches deep. Original narrow 

 tire rut almost completely lilled.) 



Run 7. Narrow tire over the same rut, 414.8 " 



(This run deepened the rut in the center 

 about 2 inches more, making a total depth 

 of 4 inches.) 



Run 8. Broad tire over the same rut, 332.5 " 



(Rut made by the narrow tire in run 7 com- 

 pletely jailed.) 



Run 9. Narrow tire in same track, 312.8 " 



(Rut cut about one inch below the level of 

 the broad tire rut.) 

 Run 10. The broad tire completely obliterated the 



narrow tire rut, 320 . 5 " 



Run 11. Narrow tire made almost no rut in bottom 



of broad tire rut, 334.2 " 



Run 12. Narrow tire. Made little impression, 321.4 " 



Run 13. Broad tire. Rut two inches. The last runs 



did not seem to have any effect, 320.5 " 



The six inch tires almost completely filled the narrow tire rut in 

 four round trips. Thus at the same time that a ton load was being 

 hauled over this road on the broad tires its surface was smoothed 

 and improved. Every run with the broad tires was a benefit; every 

 run with the narrow tires was an injury. 



Clay road, dry on top; narrow tire ruts cut in the ordinary course 

 of travel "averaged 8-| inches deep, except for a distance of 20 feet at 

 one end of the run where the ruts were 15 inches deep; w'alls of ruts 

 rigid, smooth and well spread; bottoms hard and smooth; the side 

 friction on the narrow tired wheels very slight. Length of run 

 400 feet; net load, 2,000 pounds. These trials were made on the 

 same ground as those just reported, the condition of the road being 

 practicably the same, excepting that it was slightly drj-er. Runs 

 were made in the following order: 



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