Public Highways 289 



is found, some splendid roads are found surfaced with this 

 material. In communities near the coast, shells have 

 been used for road surfacing with good effect. But prob- 

 ably the most popular and generally employed material 

 is broken stone. Roads thus surfaced are said to be 

 macadamized, being so called for the reason that John 

 London Macadam, a Scotch engineer, was the first to 

 advocate and employ this plan of road building. The 

 old Roman roads, which figure in history, were surfaced 

 with stone, in some instances the stone surface being 

 several feet thick; but Macadam worked upon the 

 theory that a smaller amount of stone properly consoli- 

 dated would serve the same purpose with less expense. 

 Time proved his theory correct, and Macadam is quoted 

 in almost every work on road construction. Another 

 Scottish engineer who advanced many splendid ideas in 

 road building and also won fame as a road builder during 

 the days of Macadam, was Thomas Telford. The Telford 

 roads are built with the lower layer of broad, flat stones 

 set on edge by hand. This is considered by many road 

 builders to be a useless expense except when the foun- 

 dation is soft. In the Mississippi delta, where the 

 roads are over sedimentary clays, commonly known as 

 "gumbe," or "buckshot," tne burnt -clay method of 

 surfacing has been successful. 



410. Earth Roads. The building of modern high- 

 ways is being urged throughout the country as their 

 importance becomes realized, especially with the increase 

 of overland traffic and the ever-increasing demand for 

 better transportation facilities from the farm to market, 

 and growing tendencies toward better living conditions 

 in the rural districts. For many years to come, the 

 earth road mileage will probably be by far greater than 

 that of surfaced road; hence the care of earth roads 



