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By VAUGHAN CORNISH, D.Se., F.R.G.S., F.G.S., F.C.S. 



N December, 1901, I noticed that the snow in some 

 of the streets in Montreal and on the driving 

 track across the frozen St. Lawrence had a 

 remarkably undulating surface, obviously due to 

 the sledge traffic. These undulations averaged 

 13 feet from crest to crest. The length of the 

 sledge-runners varies, but 5 to 6 feet is a 

 common size. The height of the undulations varied consider- 

 ably, 8 inches being, however, about the usual height, reckoned 

 from trough to crest. The profile was symmetrical both in the 

 single track across the frozen St. Lawrence and in the streets, 

 where the track is double and the sledges keep to the right hand 

 side. In this case, however, the ridges were not quite at right 

 angles to the course, the ridge being pushed slightly at both 

 ends in the direction in which the sledges are driven, indicating 

 a small amount of movement since their formation 



Upon a toboggan-run on Mount Royal, made in snow without 

 the use of water, similar undulations were in one instance 

 produced. 



These undulations are called cahots, or jolts, which is the same 

 word as is used for holes in ordinary roads. 



