SNOW-MUSHROOMS AND CAHOTS 249 



wet the cahots might at first travel, but when dry- 

 weather supervenes the ridges would set in a hard 

 mass and become stationary. 



Other Examples of Transverse Inequalities of Sur- 

 face in Roads and Paths. 



The principal inequality produced by wheeled 

 traffic on a soft road or track is, of course, the 

 rut, or longitudinal furrow, but in harder roads 

 small transverse inequalities are often produced, 

 although I have never seen them attain regularity. 

 On macadamised roads the first step in their forma- 

 tion seems generally to be the kicking out of a 

 stone by the horse's hoof. The wheel soon enlarges 

 the hole, and when the inequalities thus produced 

 are examined it is seeji that they are generally a 

 succession of arcs of wheel-tyres separated by a 

 rather large stone firmly wedged. If an initial in- 

 equality be caused in a wood pavement by a bad, 

 soft block, this is speedily multiplied in both direc- 

 tions by the bumping of the wheels. 



The action of a wheel to make holes in a stony 

 road is exactly the reverse of that of a roller 

 employed for smoothing out the inequalities of 

 paths. The roller, however, is drawn slowly. It 

 is reasonable to assume that the depressing effect 



