152 ON SURFACE WAVES PRODUCED BY SLEDGES. 



remarkable, because the sledges only pass over them in one 

 direction, viz., downwards, the empty sledges being taken up 

 in the wheeled cart. 



At the foot of the hill the sledges are sometimes dragged a few 

 yards along the flat over the road at the railway siding, and this 

 piece of road was slightly, but distinctly undulated. 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 on the hillside. The average length 

 of the undulations was 14 feet 8 inches. 



I arrived at Coniston on my second visit on August 6th, 1902, 

 and occupied myself until August i6th with a further examin- 

 ation of the undulations caused by sledges. 



My first observation on ascending the steep portion of the 

 quarry road just above the railway station was that the undula- 

 tions were of considerably greater amplitude, and presented 

 more numerous ridges in continuous series than was the case in 

 September, 1901, and this I at once attributed to the circum- 

 stance that the summer of 1901 had been a dry one, whereas 

 that of 1902 had been unusually wet at Coniston. 



Plate II. shows the series of undulations here looking down- 

 hill on August 1 3th. The dimensions of a series, measuring 

 uphill, was as follows. The height was taken at both sides of 

 the track : 



Wave Length. Height from Trough to Crest (inches). 



E.H. L.H. Mean. 



13 Feet 3 Inches . . 6*75 . . 6-5 . . 6'625 

 13 , 7'75 8-75 8-25 



15 2| 

 14 6 



16 5 

 18 6 

 12 5| 



7-0 .. 7-0 .. 7-00 



7'5 .. 8-5 .. 8-00 



8-25 .. 7-75 .. 8-00 



6-75 .. 6-0 .. 6-375 



8-75 7'5 8-125 



Mean length 14 feet 9-4 inches. Mean height 7*5 inches. 

 Wave-length divided by Height = 23-653. 

 Wave-length divided by Length of Sledge = 3'225. 



