4 BULLETIN 220, U. S. DEPARTMENT OF AGRICULTURE. 
FRENCH CONSTRUCTION PREVIOUS TO 1775 (ROMAN METHOD). 
By the time that road building was revived in France, in the 
seventeenth century, the Roman methods of road building had been 
greatly modified, though the Roman form, especially in the founda- 
tion, was still retained. Under the ministry of Colbert (1660-1669) 
as controller general of finances, about 15,000 miles of stone roads 
were built, practically all with an undrained foundation consisting of 
one or more layers of large flat stones placed in the bottom of a 
trench-like excavation. These stones were then covered with a thick 
layer of more or less finely broken stone. As no systematic main- 
tenance was attempted, the roads rutted badly, and it was only rarely 
that the broken stone consolidated properly. The total thickness of 
the roads was from 1J to 2\ feet. 
Plate II, figure 2, illustrates the type of road constructed in France 
previously to 1775. This type was modeled on the Roman system. 
Section A shows the earth foundation, which was flat. 
Section B represents the first course.' This course was composed of 
flat stones laid by hand in two or more layers. The total width of 
this course was 18 feet and the depth was from 9 to 10 inches. 
Section C shows the second course, a layer of small stones, which 
were broken in place with hand hammers. 
Section D shows the finished surface. This course was composed 
of stones broken by hand into sizes smaller than the underlying 
material. It was left to be consolidated by traffic. The total thick- 
ness of the road in the center was from 18 to 20 inches and at the sides 
from 12 to 14 inches. 
TRESAGUET METHOD. 
About 1775 a form of construction, supplemented by continual 
maintenance, came into prominence in France. It had long been 
advocated by Pierre Marie Jerome Tresaguet, a noted French engi- 
neer. He held that good drainage and systematic maintenance were 
absolutely necessary for good roads. By providing a properly 
crowned and drained foundation, he reduced the required thickness 
more than one-half and provided a better and more serviceable road. 
The small stones were broken more uniformly and, by a little atten- 
tion after placing, soon bonded under the traffic. The resulting roads 
were smooth and afforded comfortable traveling. 
Plate III, figure 1, illustrates the type of road constructed in France 
by Tresaguet from 1775 to 1830. 
Section A shows the earth foundation shaped parallel to the finished 
surface. 
Section B represents the first course, which was composed of flat 
stones laid on edge lengthwise across the road and beaten to an even 
surface. The depth of this course was about 5 inches. 
