The Providence news. (Providence [R.I.]) 1891-1906, 1893-12-14

A5ise which suggests great resistance,
and if properly handled tits easily broken
by machinery to fairly uniform size.
Limestones are both good and bad.
The softer limestones wear rapidly, form
a good road on which mud collects and
yield rapidly to the effects of weather.
The upland, or mountain limestones, on
the other hand, are frequently well
adapted for use as road metal. They
bind quickly and make a smooth and
durable roadway. The rubbing and
wearing of hmestones form q dust
which, when wet, becomes sort Of NOR
tar, filling the spaces between the pieces
Of stone and consolidating the entire
roadway into solid and sometimes into
durable crust. Some of the best lime
stones are found in the Devonian and
the older silurian rocks.
GRANTEES generally inferior because Of
excessive brittleness due to the feldspar
contained in it, but syenitic granite Of
ten makes an excellent road metal.
Sandstones are generally inferior, but
some sandstones contain iron, which
hardens and toughens them, and in these
exceptional cases sandstones may be eused
to advantage.
The construction of macadam road
in any given locality generally involves
the use of material found near at hand,
and where local quarry does not exist
field stone and stone gathered from the
beds Of rivers and small streams may be
made to serve. every purpose. Many of
the stones and powders thus obtained
are of traprock, and in general it may
be said that all hard field stones and
river stones, if broken to a proper size,
will make fairly good and sometimes
very excellent road metal.
No elaborate test IS required to deter
mine the hardness of any given speci-
men. A steel hammer in the hands of
an intelligent workman will reveal in a
general way the relative degree of tough
ness of two or more pieces of rock. Field
stone and river stone offer an additional
advantage in that they are quickly han
died, are generally of convenient size,
and are more readily broken either by
hand or by machine than most varieties
of rock which are quarried in the usual
way.
1t is a simple task to break stone for
macadam roadways, and by the aid of
modern inventions it can be done cheap
ly and quickly. Hand broken stone is
fairly out of date and is rarely used in
America where any considerable amount
of work is TO be undertaken. Stone may
be broken by hand at different points
along the roadside, where repairs are
needed from time to time, and by GRIM
inals confined in penal institutions, who
could not be otherwise profitably en-
ployed, but the extra cost Of production
by this method forbids its being carried
On where extended work is undertaken.
Hand broken stone is generally more
uniform ia size, more nearly cubical in
shape and has sharper angles than that
broken by machine and is undoubtedly
superior to the machine made road met
al, but the latter when properly assorted
or screened has been found 10 meet
every requirement.
In breaking by hand two steel faced
hammers Of different weights are used.
One weighing from five TO six pounds is
used for sledging the powders and large
pieces into smaller sizes, and the other,
a small steel faced hammer weighing
about one pound and having strong
flexible handle, is used for breaking tho
stones into proper size for use on the
road. In breaking by hand skilled la
borer will break from one-half n cubic
yard to three or four cubic yards per
day, according TO the skill Of the work
man and the toughness OF the stone.
American stone crushers are now used
in all parts of tho civilized world. They
present considerable variety in design,
size, cost and capacity. A good crusher
driven by eight horsepower wifi turn ont
from 40 TO 80 cubic yards Of two inch
stone per day Of 10 hours and will cost
from s400 upward, according to quality.
Good Roads.