170 



AGRICULTURAL ENGINEERING 



road where the side ditch is to be located, using one corner 

 of the blade. The earth from this furrow is then scraped to 

 the center of the road and spread by the grader. 



Elevating Graders. The elevating grader is a compli- 

 cated machine in many respects. It is provided with a four- 

 wheel carriage and a plow that is operated at one side. An 

 endless apron driven by power from the rear truck-wheels 

 receives the earth from the plow and elevates and discharges 

 it either in the center of the road or into wagons drawn 

 beside the grader. These machines may be operated either 

 by horses or by traction engines. The standard machine 

 requires 12 horses, eight in front and four behind. This 



Fig. 92. An elevating grader. 



machine will grade a new earth road in good soil at the rate 

 of a quarter of a mile per day, where the width does not 

 exceed thirty feet and where a crown of twelve inches at 

 the center is made. Elevating graders vary somewhat in 

 size and weight. 



Horse Rollers. Horse rollers for road construction con- 

 sist essentially of a large cast-iron drum with a frame and 

 tongue for drawing. They are usually made 4 to 6 feet wide 



