The Ottawa free trader. [volume] (Ottawa, Ill.) 1843-1916, 1890-03-15
3oHEI

HALE OF CROSS SECTION.

eff the stone for the foundation-for
which most anything will do, and that
kind should be taken which is cheapest
to procure-happens to be got out cheap
est in larger pieces than the above dimen-
sions, it will do no harm. This founda-
ton course is sometimes set so as TO pre-
sent an inclination on top, and the cover
then put on of uniform thickness over
the whole breadth. This is perhaps best,
but is somewhat more expensive. 1t will
do, in nearly all cases, to set the founda-
ton course on level, or as near so as
the stones will allow, and then make the
top browning, by making the covering
say three-quarters of an inch or an inch
less thick at the edges than in the center.
The stones forming the foundation should
not be set in rows, nor ever laid on their
fiat sides, but set up on edge and made
to break joints as much as possible; that
is, set up irregularly. After they are set
up, the points that project above the
general level may be broken off, and the
interstices generally filled up with small
stone.
more or less care and work are neces-
sary in this part of the operation accord
ing to the importance of the road and
the depth and character of the material
used for the top covering. To roll the
road at this stage is to be recommended;
afterwards it becomes requisite. The
point never to be lost sight of is that this
foundation course must remain porous,
must be pervious to water, 80 that all
rain water that shall soak through the
top covering will find through it means
of escape to the ground underneath;
thence, according to the nature of the
subsoil, it is left either to soak into the
ground or must be further led away by
appropriate drains"
Another authority in the same work,
writing upon the top surface for stone
road, says:
Experience has shown that while six
inches may be sufficient depth for light
travel, twelve to eighteen inches are
necessary If heavy loads must be carried
at all seasons of the year. For country
macadam roads the limits would be be-
tween six and twelve inches, according
to the character of the subsoil. For the
thorough construction of macadam roads
the stones are now crushed by machinery
and then rolled with steam road rollers
of ten to fifteen tons weight. The weight
of the roller per square inch on the bear
ing surface should be equal to the ex-
pected weight, per square inch, under
the wheels of the heaviest loads.
"Where thorough work of the best
character is wanted, engineering skill
and experience are requisite, but the gen.
eral methods may be briefly stated, so
that wherever bad sloughs need filling up
with stone, the macadam plan may be
followed at least approximately. The
trench or road bed should be dug out to
the required width and depth, the larger
stones should then be selected and firmly
packed together across the foundation
in irregular courses, in the general form
of street pavement. They should all
rest on their --LATEST or broadcast surfaces,
and the thin or Jagged edges upward.
The interstices or spaces should be close
ly filled up with chips and the whole
layer be well rammed or rolled into
solid mass.
"On top OF this place layer OF finely
broken stone of the thickness requisite
10 bring the surface to grade, with a
good crown in the center. This should
be rolled until the whole mass is firmly
bound together. and then covered with
sharp gravel or fine screenings OF broken
stones of sufficient depth to bed and bind
the layer of broken stone. In the future
of such road the inost i'm
portant point is to prevent the formation
Of ruts, by keeping the surface so uni
formly even that there will be no induce
ment for travel to follow beaten tracks.
The cost of the macadam structure pre-
cludes its use on country roads, except
10 occasional bad spots where stone is