ROADS AND BRIDGES 



317 



The elevating grader, Figures 202 to 204, inclusive, is 

 used in a manner similar to that described for the revers- 

 ible machine in grade construction. While plowing is 

 sometimes necessary to loosen the earth that it may be 

 easily moved by the reversible machine, the elevating 

 grader has its own plow. Eight to sixteen horses are 

 required to operate this powerful machine. It is managed 

 by one man, while each driver guides four or even eight 

 horses. It does not place the earth in position to form 

 a well-rounded road and the reversible road machine 

 must be used to finish the crown of the grade. In 

 Figures 205 and 206 are shown how the earth is piled in 

 one or two ridges accord- 

 ing to the width between 

 the ditches and the length 

 of the elevating belt in 

 use. The dotted lines in 

 these two figures show 

 the curved surface when 

 the reversible road ma- 

 chine has been used to 

 smooth the ridged sur- 

 face left by the elevating 

 grader. 



The drag or slush 

 scraper (see Figure 106) , in 

 addition to being a more 

 expensive means of car- 

 rying the earth from the ditch to the center of the road, 

 is not so well adapted to making a good road surface 

 as either of the machines mentioned above, though it is 

 an indispensable implement to use in many places where 

 it is not practicable to use the larger machines men- 

 tioned. The material thus placed in the center does not 

 pack or wear evenly and ruts soon form in the wheel 

 tracks. Where the reversible machine can be procured, 



Figure 201. Reversible road machine cut- 

 ting away a bank to widen an old road, 

 showing how the blade may be set so as to 

 -each out beyond the wheels and cut down 

 the bank. 



