ASPHALT PAVEMENTS. 613 



to drain off the rain-water. The powdered asphalt is then spread over 

 the surface, to a depth of 16 to 20 inches (according to the amount of 

 traffic), and stamped down. Then a heavy roller is drawn over it. 



With regard to the danger of horses slipping and falling on the 

 smooth surface of the asphalt pavement, the following facts are of 

 interest : 



At Lyons, which has long had mastic roads, a number of cavalry- 

 horses fell on a street of compressed asphalt. This accident arose from 

 the circumstance that the asphalt had been laid on an old macadamized 

 road, and had therefore that considerable arch which is unnecessary 

 and dangerous for the asphalt road. The cavalry riding in a long 

 line, those horses near the side of the road slipped on the steep incline. 



At Marseilles, where the asphalt roads from the harbor to the 

 town were made with a very gentle curve, there has been no increase 

 in the -number of accidents, though the traffic is enormous. A very 

 slight arch of the road is quite sufficient to allow the rain to run off 

 from such a smooth surface. 



It is also not advisable to lay the asphalt on any street with a 

 gradient greater than 1 in 60, though in London some streets having 

 a gradient of 1 in 57, and even to 1 in 46, have been covered with as- 

 phalt without any apparent danger. It is of course extremely difficult 

 to get any accurate information about the number of accidents on the 

 streets, general vague impressions being worthless ; but in Paris the 

 number of horses which were observed to fall in the Rue Neuve des 

 Capucines, during two months, was as follows : In the former, which 

 was paved with sandstone, in blocks, from Fontainebleau, one horse in 

 1,308 fell ; on the latter, which was covered with asphalt, one in 1,409, 

 so that the balance was in favor of the asphalt. 



In snow or frost asphalt is not so slippery as granite, being in it- 

 self warmer, and also more easily warmed by the slightest rays of the 

 sun ; hence, the ice is more slow in forming, and quicker in melting, 

 than on granite. 



It has been proved that the greatest number of accidents to horses 

 happen when the asphalt is not cleaned, for the surface is never 

 muddy or greasy, except with foreign matter, and this ought to be 

 constantly washed off with water, which is plentifully laid on in Paris, 

 and to some degree in London. At any points where this cannot be 

 done, a slight sprinkling of coarse sand will prevent the horses slip- 

 ping. This is only a temporary remedy, but valuable in case of emer- 

 gency. It is one of the great advantages of asphalt, however, that it 

 is so easily and cheaply cleaned. 



In case of a conflagration, the asphalt pavement will not help to 

 spread it. In London heaps of wood were set fire to on asphalt pave- 

 ments, but, when the embers were raked away, there were only a few 

 weak flames seen issuing from the asphalt, and they went out of their 

 own accord in a few moments. 



