EOAD MODELS. 3 



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 

 were 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. 



