Evening star. [volume] (Washington, D.C.) 1854-1972, 1906-04-15

the toughness another machine is used. IT
Is built like miniature pile driver and
a small hopper Is raised and allowed TO fall
on a round section of stone, such as was
used in the first test for hardness. The
little hammer is raised farther each time
and allowed to drop on the stone till the
stone Is broken by the impact.
Then the binding quality is determined.
The stone is ground to an impalpable dust,
mixed with water and nodded into a small
cylinder. This is put under one of the
little hammer machines and tested till 1t is
crushed by the blow. Some stone that is
otherwise very satisfactory has little or
no binding qualities and breaks at the
first blow. Others stand up well under
the test showing that they would make
a good road surfacing material. Some
times these tests show that one of two
varieties of stone In a locality would be
best for the foundation of the road, while
another would be the thing for the top
dressing.
There is another curious machine devised
by the French school of roads 1t con
sists of lot of heavy iron pots that can
be boted to a zigzag revolving SHAFT. These
are filed with samples of stone of a. stand
ard size, and the whole set to whirling on
the shart for an hour or so. At the end OF
that time the pots are emptied, the amount
OF dust produced carefully weighed and the
expert Is able to tell just the relative
wearing qualities OF the samples submitted,
Samples Sent ia Daily.
Samples are sent In TO the ONCE ddlly-
There is a great awakening all over the
country on the subject Of road construc-
ton, and the government while it cannot
build roads itself for the various communi-
ties is ready to give expert advice not
wherever It IS wanted but so far 1t is
able. The fact is that the requests for
engineers and advice far outrun the capac-
ity of the office. There are men out now
in all sections of the country, several par
ties along the Atlantic seaboard, some in
the middle west, in the far west and on
the Pacific coast. Wherever 81 community
shows itself thoroughly In earnest and Is
willing to spend good money in road con-
struction the road office does Its best to
get working party there.
1t has developed several schemes that
have been of value in road building. Ref
erence was made in The Star some time
ago to the burnt clay roads that had
been tried in the gumbo mud regions of the
south These have proved a success and
have stood UP we'll making roads possible
where there is no stone and where there
has never been wet weather road before.
The burnt clay idea is being developed
with view to helping out other communi-
ties where rock is scarce. There are
good many places where there Is dearth
of good road building rock Clay is plenti-
full to the point of being a nuisance In
good many places, especially in Virginia,
where Virginia mud has passed into
proverb. The road office is now expert
menting with burning the Virginia clays,
and owing to the fact that clay once burnt
loses its power of getting sticky under the
action Of water there is some hope that
the road problem In Virginia may be partly
solved through the burnt clay agency.
The office has carried on a good many
other interesting experiments, among
others the use of tar and oil roads,
and while It is too early yet to say just
how surfaces treated In this way will
wear, the results so far obtained have been
satisfactory and promise well.
There is, as has been said a dearth of
highway engineers In this country. and