ROADS AND BRIDGES 315 



surface, but in the majority of instances the material thus 

 rounded up makes a good road only when the weather 

 is dry. 



Figure iQSx shows the road machine doing its own plow- 

 ing in starting a ditch. Usually the better way is to first 

 throw out a furrow-slice with a road plow, shown in Figure 

 198, or with a common stubble plow, then carry it over 

 toward the center with the blade of the reversible 

 machine. Figure 199 shows a reversible road machine 

 shoving a furrow-slice toward the center of the turn- 



Figure 199. Keversible road machine moving a furrow-slice toward the center of the road. 



pike. The blade is like an extended moldboard, which 

 carries the earth over two or more feet each time around. 

 These machines are called reversible, because there is a 

 mechanism for placing the blade with the end now dis- 

 charging the slice of earth in front, and the end now 

 in front behind, thus enabling the machine to plow 

 right-hand in one direction and, turning about, serve as a 

 left-hand plow and throw the same furrow slice over 

 still further. On a road with a level cross-section, 



