l8o SLIPPERINESS CH. X 



made with a very hard lava, closely jointed, are per- 

 fect for wheels, but extremely slippery for horses.* 



Elaborate experiments were made in London in 

 1873, by William Haywood, Engineer and Sur- 

 veyor to the Commissioners of Sewers, on the 

 slipperiness of pavements ; they are described in a 

 Report entitled : Accidents to Horses 011 Carriage- 

 way Pavements. Many thousand passing vehicles 

 were observed and the falls of horses recorded, in 

 certain streets paved with different materials. The 

 observations showed that on stone a horse falls 

 once in travelling 132 miles, on asphalt, once in 191 

 miles, and on wood, once in 330 miles, proving the 

 great advantage of wood as affording a good foot- 

 hold to the horse. 



The following results are quoted from pp. 72, y^ : — 



' On the average of the whole fifty days' observa- 

 1 tions, the Granite was found to be the most slippery, 

 ' the Asphalt the next so, and the Wood the least. 



' Separating the accidents under three conditions 

 ' of surface as regards moisture, it appears : 



' That Asphalt was most slippery when merely 

 ' damp, and safest when dry ; 



* Within the last few years, the introduction of india-rubber pads 

 in the horses' shoes have overcome this difficulty and it is now (1900) 

 a rare thing to see a horse fall in the streets of Rome. The pad is, 

 in effect, a shoe inside of the iron shoe, so much thicker that it 

 touches the ground below the iron. It is sometimes open at the 

 back, sometimes closed and covering the frog. The outer portion 

 is expanded into a thin web which lies between the hoof and the 

 shoe ; the nails, passing through this web, keep the pad in place. 



