cheaper in
construction,--the labor of preparing and handling the stone, and of
excavating the wider trench that stone requires, amounting to more than
the cost of the tile, even with a high charge of transportation added.
Incidentally it is proper to say that where tiles cannot be had, a mass
of gravel or fine cinders, six inches wide and six inches deep, placed
at the bottom of the drain, and _covered with well-packed soil_, is
preferable even to broken stone or any other form of channel that would
permit of the rapid running of water and the washing into the drains of
even a slight amount of silt.

The removal of excessive subsoil moisture being secured, attention
should next be given to the surface of the road, which should be
finished with the firmest material at hand,--with the common earth of
the subsoil where nothing better can be afforded,--and which should be
brought to a true grade, with a _very slight_ slope from the centre to
the edge. For a road thirty feet wide, the elevation of the centre
above the level of the edges should not be more than four to six inches,
and the grade should be made on a straight line rather than on a curve.
If the road is made as flat as the turning-off of surface-water will
permit, it will be travelled upon in all its parts; while if it is
crowned to a high arch, as is often the case, it will soon be found that
the best place to drive is in the middle of the road, and foot-tracks
and wheel-tracks will soon form slight channels or ruts which will lead
water lengthwise along the road, and which will cause an undue amount of
wear and washing. A road may be actually flat to the eye, and equally
convenient for travel at every part of its width, and still have enough
lateral slope to cause water to run off from it.

It is especially desirable that no surface-water flowing from the
roadside (above all, when frost is coming out of the ground in the
spring) be permitted to run on to the road. This should be effectively
prevented by the formation of sufficient gutters, with such outlets as
will prevent ponding at the sides of the road. When it is necessary to
carry the water of the gutters from one side of the road to the other,
culverts should be provided; and wherever the slope of the road is
sufficient to cause water to flow along it lengthwise,--that is,
wherever the inclination is more than about one in fifty,--there should
be frequent slight depressions from the centre diagonally t