CH. X ASPHALT AND WOOD I 79 



' most skilful and careful workman cannot possibly 

 ' replace the stones, even if they are marked, so as 

 'to form the orio-inal continuous surface.' 



The asphalt and wooden pavements now rapidly 

 being introduced in cities, while not better for 

 draught than stone, have the great advantage of 

 diminishing the noise. Both are worthless unless 

 they are underlaid by a thoroughly well-made con- 

 crete foundation. Indeed, it cannot be too posi- 

 tively asserted that the surface, whether it is stone, 

 wood, asphalt, or macadam, is only a surface, and 

 that the true road is below, which if once well made 

 and not injured by excavations, should last indefi- 

 nitely. The surface can be renewed as it wears 

 out. The wooden pavement, known in America 

 as the Nicholson, and others of its kind, were laid 

 on a lining of thin elastic boards upon poorly pre- 

 pared foundations of earth or gravel. These pave- 

 ments soon went to pieces, and gave a bad name to 

 wooden pavement of all kinds ; but creosoted wood, 

 laid as it should be, on a perfectly firm concrete 

 foundation, makes the best covering that has yet 

 been found, being nearly as smooth as asphalt, and 

 less slippery. The application to the wood, from 

 time to time, of very sharp, finely broken stone, 

 almost like coarse sand, which is forced into the end 

 grain of the wood by the traffic, gives the horses' 

 feet a better hold. A pavement must always be a 

 compromise : if it is very smooth it is slippery. 

 Certain stone pavements in the streets of Rome, 



