474 



Farm Mechanics. 



advocating a roller of 3.5 to 5.5 tons, while others hold 

 that only one of 15 to 20 tons weight will serve the purpose. 

 Others advocate a light weight to begin with and a heavier 

 one at the close. 







FIG. 226. View showing horse roller at work compacting the road metal. 



590. Amount of Rolling. The only general rule which 

 can be given in regard to the amount of rolling a given 

 layer should receive is that the work should be continued 

 until the stones cease to move in front of the roller or un- 

 til the roller no longer sensibly depresses the bed and it 

 has become hard and smooth. It should be kept in mind, 

 however, that the road may be rolled too much, or until 



