172 



AGRICULTURAL ENGINEERING 



Rock Crushers. One of the essential machines in con- 

 nection with the building of a stone road is the rock crusher 

 for reducing stones to fragments of the proper size. Usually 

 these crushers are located at the quarry, and the stone is 

 shipped ready for application to the road. 



Fij 



93. Stone crushing plant. A three-wheeled steam roller and a 

 dump wagon are shown in the foreground. 



Other Machinery. The equipment necessary for build- 

 ing stone roads includes several other machines. Among 

 these may be mentioned screens for grading the stone, dump 

 wagons for hauling and spreading the stone, and sprinklers 

 for applying water or binding material in the form of a 

 liquid. When old roads are to be repaired, plows or scari- 

 fiers, Yvmich are heavy tools with cultivator-shaped teeth for 

 breaking up the surface, are necessary. 



