ly uncomfortable for the users of a highway if sods and weeds
in quantity are left in the road after it has been graded. The humus
that will be left in the soil as the vegetable matter decays increases
the porosity of the road surface making it more absorbent than soil
without humus. This increases the susceptibility to softening from
storm water or ground water.

The tractor can advantageously be used to draw the elevating grader on
this class of work, but will be greatly handicapped if there are wet
sections along the road, through which the tractor must be driven. In
many cases its use is prohibited by such conditions and for all-round
service of this character, mules are preferred for motive power.

[Illustration: Fig. 12.--Tractor-grader Outfit]

=Use of Blade Grader.=--Heavy blade graders designed to be drawn by a
tractor are suitable for shaping the earth road. Some of these have
blades 12 feet long and excellent control for regulating the depth of
cutting. Often two such graders are operated tandem. These machines
have a device which permits the operator to steer the grader
independently of the tractor. Thus the grader can be steered off to
the side to cut out the ditches, while the tractor continues to travel
on the firm part of the road. Earth moved with the blade grader is
usually fairly free from large lumps and can readily be smoothed to a
satisfactory surface for the use of traffic. The sods and weeds will
be drawn into the road along with the earth just as they are when the
elevating grader is employed. Precaution must therefore be taken to
eliminate them before the vegetable matter decays, and to smooth the
surface for the use of traffic.

=Costs.=--The cost of shaping an earth road in the manner described
above will vary through rather wide limits because the nature and
amount of work to be done varies so greatly. Some roads can be graded
satisfactorily for $300.00 per mile, while others will cost $700.00.
But $425.00 per mile may be taken as an average for blade or elevating
grader work plus a moderate amount of grade reduction in the way of
removing slight knolls. For the amount of grade reduction necessary in
rolling country, followed by grader shaping, $1000.00 to $1800.00 per
mile will be required. The method is not adapted to rolling country
where the roads are undulating and require some grade reduction on
every hill. For hilly roads one of the methods described for grade
reduction will be re