ON SURFACE XVAVES PRODUCED BY SLEDGES. 153 



It will be observed that the length of the undulations was 

 practically the same as in 1901, the same sledges being in 

 use. 



On another flank of the Coniston " Old Man " is a track from 

 another slate quarry (Cove Quarry), on which sledges are 

 employed. On this track also I found the undulations. They 

 were not so highly developed as on the Saddlestone Quarry 

 track. The roadway itself was very loose, wet, and slushy. A 

 group of four ridges measured from crest to crest 13 feet, 

 1 8 feet, 13 feet, and 15 feet, with an average wave length, 

 therefore, of 14 feet 9 inches. The sledges were quite similar 

 to those used upon the Saddlestone Quarry track. The experi- 

 ments subsequently made convinced me that the inferior 

 development of the cahots on the Cove Quarry track was due to 

 deficiency of binding power of the road-bed. 



EXPERIMENTS UPON THE PRODUCTION OF CAHOTS. 



With the kind assistance of my friend, Prof. J. B. Cohen, of 

 the Leeds University, I proceeded to experiment upon the 

 production of cahcts. Obtaining a basket which had a form 

 something like a Laplander's sledge, and not unlike a rather flat- 

 bottomed boat, I repaired to the little delta or beach of sand 

 and shingle made by a brook on the shore of Coniston water, 

 near to the Steamboat Pier. Having weighted my " sledge," 

 which, be it observed, was not on runners, and should, therefore, 

 have produced its " cahoting" effect more quickly, I proceeded 

 to haul it about on the coarse sand and fine shingle of the 

 highest portion of the beach, several feet above the level of the 

 lake. It displaced the material in a wave before its bows, 

 but left a flat, not an undulating, track. 



I then tried the effect of drawing it backwards and forwards 

 over the same track, thinking that in this way I might produce 

 some effect; much as oscillating water-currents appear to have 

 more effect than continuous currents to ripple sand. Nothing, 

 however, came of this variation of method ; the track remained 



