EOAD MODELS. 6 
reign of Caesar Augustus, when Roman road building seems to have 
reached its height, was a massive road from 16 to 30 feet wide, from 
3 to 4 feet thick, and laid in 3 or 4 courses. The first course was 
almost invariably of large, flat, field or quarry stones laid on the earth 
subgrade, except in swamps, where poles, logs, brush, or even boards 
wore used beneath the stone course. The other courses varied 
extremely with, the available material and the period and importance 
of the road. Either small stones, with and without mortar, or gravel, 
broken brick, tiles, etc., were used for the second and third courses. 
The surface or wearing course consisted of well-cut, irregular, close- 
fitting polygonal blocks on a few of the more important roads, but 
more often it consisted of uncut stones, not unlike our cobblestone 
pavements, or of gravel, and in some cases of a mixture of sand and 
clay or clay and gravel. 
Some of the more important roads near Rome were practically 
lined with temples, porticoes, and statues. On all roads inscribed 
milestones were placed at regular intervals. 
Plate II, figure 1, shows a model of the Appian Way. This is the 
highest type of road constructed by the Romans. 
Section A shows the contignatum pavimentum, composed of lime 
and sand, straw, rushes, or reeds, and sometimes laid on sills or boards. 
Section B shows the statumen, or foundation, composed of two 
courses of flat stones laid dry or in lime mortar. The depth of this 
course was from 16 to 18 inches. 
Section C shows the rudus, or rubble, composed of broken stone 
mixed with lime in the proportion of 1 part of lime to 3 parts of stone. 
Sometimes the material was taken from old buildings. This course 
was laid from 6 to 9 inches deep. 
Section D represents the nucleus, composed of coarse gravel and 
lime used hot, or bricks, potsherds, or broken tile mixed with lime 
and covered with a thin layer of lime mortar. 
Section E shows the summa crusta, or pavimentum, consisting of 
polygonal blocks joined with the greatest nicety. This course was 
about 6 inches deep and about 16 feet wide. 
Section F indicates the curbs, which were 2 feet wide and 18 inches 
high, with mounting blocks as shown at G. These blocks also served 
as seats for travelers. 
Section H shows a side road, the surface of which was composed of 
gravel flushed with mortar. The width was from 6 to 8 feet. 
FRENCH ROADS. 
From the viewpoint of construction, road building in France may 
be divided into three periods — the period of Roman influence, the 
period of Tresaguet, and the modern period. 
