The star. (Reynoldsville, Pa.) 1892-1946, 1902-01-08

~ of macadam road Is about
$4,000 Il mile. and that of
building the poorest Is about $4,000.
The best will last some thirty years
with ordinary care; the poorest will
call for extensive repairs after about
two years. and viii sometimes have to
be entirely renewed within five or six
years. II all depends on the materials
used. often. the better materials are
easily available and are even cheaper
than the poorer ones. and yet are not
selected owing to the Ignorance OF the
road builders.
This ignorance for which the tax
payers suffer severely. the Govern
ment has now set itself TO destroy.
Last December 1t established in the
Bureau of Chemistry of the Agricul
tural Department ''road material Ia
boratory," the sole business of which
Is to test samples sent it and deter
mine their value for road building un-
der the conditions of actual use. When
samples of all the rocks available in u
given locality are sent to 1t. 1t will de-
termine which will give the best re-
suits under the conditions of rainfall
and temperature obtaining there.
This laboratory. which is under
charge of Mr.. l.. w. Page, of Massa-
chusetts. began work without tool
or machine and without an appropria-
tlon. this last becoming available only
on July / last. six months after the
Office was opened. Until now 1t has
rather discouraged publicity. rs II al
ready has more work on hand than II
ran attend to with the very limited
forces at its disposal. Hereafter 1t
hopes to do better.
All material sent In is tested for
abrasion. cementatlon and toughness.
and will be tested for hardness as
soon rs the proper machines can be
built. The accurate determination of
hardness. however. Is of far less inn
portance than that of the other quail
ties named.
The abrasion test determines to what
extent given material will be worn
away by given amount of rubbing,
grinding shaking together, and so on.
II Is obtained by placing fragments of
uniform size In n cylinder. where they
are agitated by machinery at rate
which ordinarily is not sufficient to
break them, and then ascertaining the
amount in which they are reduced
In size. The concentration test is
to discover the adhesive power OF
the dust ground from the substance
and cemented together by rain and by
the rolling or trampling of the road.
1t is obtained by subjecting little cy-
llnders. formed by mixing the dust
with distilled water, to the continual
blows of weight falling through n
fixed distance; some substances will
be shattered at once. but others will
sustain as many as 1000 exactly SINH
lar blows before falling 10 pieces. This
shows the ability of the material to
repair itself when put on road
Toughness is tested by the same ma
chine, n cylinder of the material as II
originally exists being subjected to the
blows of a cylinder made up by mix
ing water with It's dust 1t shows the
resisting power of the material to the
constant blows of wheels and horses
feet.
At present the laboratory refuses to
test materials intended for any pur-
pose except country road building
After a while. when larger force Is
obtained. 1t will test those intended for
fences, houses and the like, and those
artificial stones manufactured In such
enormous quantities for city uses, such
as pavements. roadways and all the
thousand and one ends to which con-
crete is now applied. The value OF
this work will plainly be enormous.
enabling 1t to be determined approzi-
mately how long any given structure
will last under ordinary conditions, in
stead of leaving this to he settled only
by the slow test Of time. - Saturday
Evening Post.