No. 6. 



DEPARTMENT OF AGRICULTURE. 



983 



Effect of Surface on Tractive Force (Various Authorities, Compiled 



by Herring.) 



Description of Road. 



•a 



B 



3 





Description of Road. 



T3 



C 

 3 



Loose sand 



Loose gravel (deep). . 

 Loose gravel (4 inches) 

 Common gravel road. 



Good gravel 



Hard-rolled gravel 



Ordinary dirt road 



Plard clay 



Hard, dry dirt road. . 

 Macadam, little used, 



Macadam, bad. 



Macadam, poor 



Macadam, common, .. 

 Good macadam, net, . 

 Best French macadam. 



448 

 320 



222 

 147 



88 



75 

 224 

 112 



89 



140 to 97 



160 



112 



6« 

 75 to 42 



45 



Very hard and smooth macadam 



Best macadam 



Cobblestone, ordinary 



Cobblestone, good 



Belgian blocl< 



Belgian block in Paris 



Belgian block, good 



Stone block, ordinary 



Stone block, good, 



Stone block, London, 



Asphalt 



Granite tramway 



Iron railway 



46 



52 tn 32 



140 



75 



56 to 26 



54 to 23 



34% 



90 



45 



36 



17 



12% to 13% 



8 to 11% 



The velocity is in all cases taken at three miles per hour. 



TABLE VII. 



Cost of Hauling Farm Products in the United States. 



•Middle states. 



