232 WAVES OF SAND AND SNOW 



It is not only in snow that sledges produce 

 cahots, as I learnt after my return from Canada, 

 during a visit to Coniston, in Lancashire, in Sep- 

 tember, 1 90 1. The road from Saddlestone slate- 

 quarry, on the hill called the " Old Man of 

 Coniston," is in places so steep that precautions 

 have to be taken in bringing down the slate. 

 Half the load is placed on a two-wheeled cart 

 and half on a sledge, which, being hitched on 

 behind the cart, serves as a drag for the steeper 

 parts of the track. When a gentler slope is reached 

 the sledge is run on to a wheeled truck. The 

 steep parts of the road down which the sledge 

 passes are all in undulations of symmetrical pro- 

 file, having, like the cahots in snow, rounded crests 

 and troughs. The sledges pass over them in 

 only one direction— viz., downwards — the empty 

 sledges being taken up in the wheeled cart. 



The length of the bottom of a sledge-runner 

 was measured, and found to be 4 feet 8 inches, 

 which is a little less than one-third of the wave- 

 length of the undulations, which was 14 feet 

 8 inches. 



I arrived at Coniston on my second visit on 

 August 6, 1902, and occupied myself until 

 August 1 6th with a further examination of the 

 undulations caused by sledges. 



