The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1883-06-30
MACADAM ROADS.
Maeadam's improvements In Road
Making.

From the 81. James Gazette:
John London Macadam, according to his
own account, came to Scotland from Amer
lea in 1888, when the Scotch turnpike acts
had been about twenty years in operation
and roads were still being made everywhere.
He got appointed commissioner of roads,
and afterwards removed to Bristol, where
he obtained similar post and was made "a
magistrate Gifted with a mania on the
subject, he began about 1894 to travel over
the country at his own cost; and these Ia
bors he continued from Inverness to Lands
End for six-and-twenty years, apparently
to search for a well made road
Macadam's plan of road-making differed
as much from the old way which he found
in operation as bridge does from a ford.
Instead of going deep for ''bottoming" he
worked solely on the top. Instead of pro-
ducing peaked, roofed-like mass of rough,
soft, rubbish, he got fat, smooth and
solid surface. In lieu of road 4 feet
through, he made one of at most 10 inches
in thickness, and for rocks and powders he
substituted stone broken small His lead
ing principle was that road ought to be
considered as an artificial flooring, SO strong
and even as to let the heaviest vehicle pass
over it without impediment. Then people
began to hear with wonder of roads 30 and
40 feet wide rising inches the centre,
and he propounded the extraordinary heresy
that better and more lasting road could
be made over the naked surface of mo-
rass than over solid rock. Another of his
easy first principles was that the native soil
was more resistant when dry then when
wet, and that as in reality it had to carry
not alone the traffic, but the road also, it
ought to be kept in condition OF the
greatest resistance; that the best way of
keeping it dry was to put over it covering
impervious to rain-the road in fact-and
that the thickness of this covering was to
be regulated solely in relation to its imper-
viousness and not at all as to its bearing of
weights, to which the native soil was quite
equal Instead of digging a trench, there
fore, to do away with the surface of the
native soil, he carefully respected it and
raised his road sufficiently above it to let
the water run off Impermeability he OBJ
tained by the practical discovery that stones
broken small and shaken and pressed to-
gether, as by the traffic on a road, rapidly
settled down face to face and angle to an
gle, and made as close mass as wall
Mankind in general now belive that this
last is all that Macadam invented; the rest
is forgotten. That important fraction of
his discoveries is what has given to us the
verb to macdamize.
Surprise followed surprise. Roads which
were mere layers of broken stones, six, four
and even as little as three inches in thick
ness, passed through the worst winters with
out breaking up, while, as the coachmen
used to say, they "ran true; the wheel ran
hard upon them, it ran upon the nail.
Commissioners could not believe their eyes
when they saw new roads made for much
less than it cost them yearl y to repair their
old ones When an old road was given
into Macadam's charge he often made a
new one of it for f08 mile, while around
London the cost of annual repairs had been
9470 a mile. For he knew that the roads
such had been the ignorant waste gen.
orally contained materials enough for their
use for several years if properly applied.
Unless the road was hopeless, he went to
work in practical, cheap way, first cutting
away the ''gridiron' of ruts in the centre
''to level with the bottom of the burrows"
then picking" the road up to depth of
four inches, removing all the chalk, clay or
mud, breaking the large stones small and
simply putting them back again, and one
of his directions to his workmen was that
'nothing is to be laid on the clean stone OH
pretence of binding" But too often the
road was so bad, as at Endham, that it had
to be removed to its foundations.
For the repairs of the road, when once
made, he always chose wet weather, and
"loosened the hardened surface with a pick"
before putting on the fresh broken stone;
things familiar to us now but paradoxes
then to all the confraternities of the roads.
In this way he had the greatest success
with the freestone near Bath, and on
road out of Bristol towards old Down,
where everybody had always said a good
road never would be made with the mate
rials available. This impossible road, of II
miles, which the postmaster-general, as
last resource, was about to indict, he per-
fected in two months, in 1916, for E55 a
mile. Indeed, as to materials, they were
to some extent matter of indifference to
him, provided they were stones, and stones
only.
Even in the breaking Of stone Macadam
made revolution He saw that able-bod-
led men standing up with heavy hammers
wasted the greater portion of their strength.
He made his stone-breaker sit, so that all
the force of the blows took direct effect on
the stone; and the result was that he found
small hammers did the work perfectly well,
and thus was enabled to confne it to old
men past hard labor, women and boys,
which reduced the cost of the broken stone
by one-half. The size to which the stone
should be broken he determined in prac-
tical way by the area of contact of an or
dinary wheel with smooth road. This he
found to be about an inch lenthwise, and
therefore he laid it down that "a stone
which exceeds an inch in any of its dimen-
sions is mischievous," that is to say that
the wheel in pressing on one end of it
tends to lift the other end out the road
In practice he found it simplest to fix
weight of six ounces, and his surveyors
carried about scales to test the largest stones
in each heap. He would allow no large
stones in even for the foundation of his
roads, for he found they very constantly
worked upward by the pressure and vibra-
ton of the traffic. The whole road was
small broken stones, even over swampy
ground.
A SNAKE IN THE GRAss.-An old
proverb says :-"Never judge a man by
the coat he wears" and l think there is