Lake Ramparts. 



233 



opened so widely that the skaters found pleasant excite- 

 ment in crossing them by flying leaps; and a crack into 

 which I once fell must have been three or four feet 

 broad. Being then quite innocent of theories, I did not 

 compare its width with the temperature, but the air that 

 day must have been bitterly cold, for my clothes were 

 frozen before I could reach the nearest house. 



Where winters are long, frozen lakes are often util- 

 ized as regular routes of travel, and when this is done 

 the cracks and subsequent bucklings constitute obstruc- 

 tions that must be dealt with, if accidents are to be 

 avoided. Often, too, the crowding of the ice against 

 the shore makes a zone of insecurity which must be 

 bridged by the roadmaker. These obstacles to travel 

 early drew attention to the expansion and contraction of 

 lake ice and led to its rational explanation. 



Finally the shoreward movement of a boulder has been 

 almost directly observed. Its change of position has been 

 noted from day to day; and as the ice melted in the 

 spring the furrow plowed by its lower edge has been 

 discovered. So the chain of evidence is practically com- 

 plete. 



There is a literature of the subject, from which I have 

 selected a few titles, but I do not seriously advise the 

 members of the Club's outing parties to consult it. They 

 will find far more pleasure and profit in personal studies 

 on the shores of the lake, especially if they are able to 

 visit them before the complete melting of the ice and 

 while the effects of the winter's thrusting are still fresh 

 and unimpaired by the wash of waves. 



REFERENCES. 



C. A. Lee. On certain rocks supposed to move without any 



apparent cause. American Journal of Science; Vol. 5, 1822, 



pp. 34-37, and Vol. 9, 1825, pp. 239-241. 

 J. Adams. Remarks on . . . some phenomena of moving 



rocks . . . American Journal of Science; Vol. 9, 1825, pp. 



136-144. 



