The watchman and southron. [volume] (Sumter, S.C.) 1881-1930, 1908-06-24


A two ton racing automobile NOV
ing at something in excess Of a mile
a minute while an impenetrable cloud
OF fog-grey rock dust hang to the
horison and marked the speeding
course Of the big machine, was the
sight witnessed by travellers on the ia
nous conduit road a dozen miles
from Washington on Thursday, April
23.
The seemingly pronounced viola
ton of the speed ordinances was
countenanced by two of the Nations
federal departments; Agriculture and
War; however, the rushing motor
car having been pressed into requisi-
ton by L. w. Page. director Of pub
lie roads. and DR.. Allerton s. Cush-
man. assistant director. in the effort
to determine the effects Of automo-
bile traffic upon macadam highways,
and the stretch Of thoroughfare was
placed at their disposal by war de-
partment officials.
While the racing car and others of
various weights and types made many
trips over the selected stretch of a
mile and half at varying rates of
speed, from to IS miles an hour, a
corps Of skilled photographers, equip
ped with the most modern devices for
photographing vehicles at high
speeds. made accurate records of the
various tests.
1t has long been known to highway
engineers that automobiles were rap
idly shortening the lives of the rock
surface roads of the world, and many
experiments have been made in the
past six or seven years to determine
the actual cause Of the damage done.
To understand how the soft broad
tires OF the modern motor car can
work an injury to the surface that
not only withstands, but improves un-
der the constant passing and repass-
ing Of vehicles with iron tires, one
must be apprised briefly Of the theory
on which, first Tresauget Of Limoges,
and later MacAdam Of Ayr, worked
when giving such highways TO the
world. The reasoned that a road sur
faced with bits Of stone would i'm
prove under wagon traffic because
the iron tires Of the passing vehicles
would constantly crush the stones and
form rock dust particles; that those
rock dust particles would not merely
fill in all interstices between the
stones. but would also form a sur
face dust binder: the wettings and
rollings tended to cement the dust
into shell-like surface and thus
make the entire road one traffic-with-
standing, water-shedding mass.
The reasoned we'll and wisely. The
macadam roads lived up to the the
cries Of their inventors and improved
with the passing years until the ad-
vent Of the automobile. 1t was but
shot time after it came into vogue
that highway engineers In all civilized
lands learned that a new condition
was confronting them and that es.
tablished customs were being menac-
ed. The trouble was quickly traced
to the automobile and It was studied.
1t was soon noted that he soft rubber
tire was the highway menace. It
crushed no rock itself and therefore
contributed no quota Of the needful
surface dust binder. while the tre-
mendous tractive force Of the rear
wheels drew up the dust made by the
iron tired wagons and sent it whirl-
ing away over adjacent lands.
Those who witnessed the expert
ments on Thursday near the National
Capital could not doubt for a mo-
ment that the various road experts all
over the world are correct in their
opinion that very rapidly driven au-
tomobiles are rapidly tearing up the
surface Of the macadam road, for
not only were huge clouds Of dust
lifted into the air and blown of the
road. but careful examination showed
that the material under the wheel
tracks OF the machine was distinctly
loosened and ravelled even during the
short period Of these tests.
No such effects were noticeable af.
ter the passing Of iron tired vehicls;
the series Of these tests beginning
with the passing of a horse drawn
vehicle. This was photographed as
1t moved along and also as the wagon
tires passed over a given mark. Then
the automobiles were sent over the
course. The first was a heavy
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