HOUSE AND GARDEN 
July, 1910 
a wagon tree. One 
pair of the ends of 
these parallel planks 
lag behind the oppo¬ 
site ones, giving the 
scraper an angle of 
some forty degrees 
with the wagon tree. 
The drag is drawn 
along the side of the 
road with the lagging 
end towards the cen¬ 
ter, tending to throw 
the loose dirt towards 
the crown. 
Sandy roads are 
improved by a top 
dressing of earth, and 
in some Western lo¬ 
calities straw is also 
thrown down on it to 
make a more compact 
surface. With roads 
built largely of loam 
or clay, on the other 
hand, the addition of 
sand is an improve¬ 
ment. 
With macadam roads, which are always more desirable, a 
well graded and substantial foundation of an earth road, such 
as described, is essential. Trap rock is a universal favorite for 
the macadam surfacing, with granites and limestones next ap¬ 
proaching it in value. For a four-inch depth of macadam, the 
lower layer may be of stones ranging from three-c|uarters of 
an inch to two inches in diameter, rolled down preferably by a 
very heavy roller to a depth of two inches. For the second layer, 
stone from an inch to an inch and a half in diameter is used, 
rolled to a depth of one inch, the roller working along the sides 
first and the middle last. A top layer of half-inch stone and 
dust is then put on dry, being rolled and well wet down succes¬ 
sively until it completes the total four-inch depth. In a twelve- 
foot driveway this macadamizing will cost from $10 to $15 per 
rod, which, of course, must be added to the cost of the earth 
foundation. 
One of the great 
road problems of 
modern times has 
been brought with the 
automobile. MacAd- 
am was building for 
a traffic of vehicles 
weighing a ton or less 
and moving no faster 
than ten miles an 
hour. Let a 3000- 
pound motor car whirl 
over his carefully 
built driveway at thir¬ 
ty miles an hour, and 
a great cloud of his 
precious bonding dust 
goes swirling into the 
air and over the neigh¬ 
boring shrubbery. 
Investigating more 
closely into the prob¬ 
lem, he would learn 
that the driving- 
wheels of the car 
register a greater 
mileage on the odo¬ 
meter than the front 
ones do. The rear tires, despite their broad clinging contact and 
the heavy weight they carry, are constantly slipping. An emery 
wheel could hardly be more effective in grinding and pulveriz¬ 
ing the brittle macadam surface. The old Scotchman himself 
would be quick to confess that his surfaces were not designed 
to resist such strains. 
So progressive highway builders of to-day have thrown away 
much of MacAdam’s teaching and have rewritten the whole sci¬ 
ence of road construction into conformity with modern demands. 
No longer does the builder of long driveways or public roads 
cement his surfaces with wet stone dust—the dust would be 
gone in a month. Neither does he make his surfaces hard, for 
a hard surface opposes just the dry brittle resistance to the 
abrasive wheel that it needs in order to produce powder. Coal 
Tar, that wonderful mother of so many commercial articles, rang- 
(Continued on page 52.) 
A reclaimed swamp on the estate of W. J. Chalmers, Lake Geneva, Wis., where the 
top dressing is gravel. Jens Jensen, landscape architect 
A private driveway in Illinois where the drainage problem is solved 
by blind drains with occasional grating-covered openings 
A tar-treated macadam road in Massachusetts where the automobile 
dust had previously been a serious nuisance 
