1 6 Transactions of the Canadian Institute. [Vol. IX. 



summer, for in the latter season, though the forests and swamps may 

 act as efficient reservoirs, the moisture which falls as rain runs off con- 

 tinuously and rapidly into the streams and lakes as soon as it falls, while 

 in the winter the moisture which falls as snow continues to pile up day 

 after day and week after week, very little water soaks into the ground 

 to supply springs, the surface run-off is almost entirely stopped, the supply 

 of water flowing into the lakes is greatly reduced, and consequently the 

 level of the surface of the water in the lakes drops very considerably. 

 As the ice is floating on the surface of the water it necessarily falls into the 

 water, except along the shallow shores where it was first formed and where 

 it is now frozen to and rests on the sand and gravel of the bottom. 



If it were possible for the water to drain completely out of the lakes 

 the ice which had first formed on them would then sag down and rest on 

 the bottom everywhere, but this is not possible, for the outlets of the lakes 

 are sufficiently high to prevent the water from draining entirely out of 

 them, but, nevertheless, the ice sags down as much as the outlet of the 

 lake will permit and therefore it slopes downwards for a certain indefinite 

 distance from the shore towards the lake and then merges into the general 

 level ice which is floating on the water. 



As I have already stated, most of the ice is floating on the water, 

 and for a longer or shorter time, according to its thickness, its has buoy- 

 ancy and strength enough to hold up the load of snow that falls on it. 

 If snow falls to a considerable depth soon after the ice is first formed it will 

 press the ice down into the water, for an inch of ice will only carry about 

 five-sixths of an inch of dry snow, so if the ice is three inches thick it will 

 carry two and one-half inches of dry snow but no more. In such a case, 

 if the fall of snow has been greater than two and one-half inches it will 

 press the ice down and the water will rise up through air holes, fissures, 

 etc., and wet the under part of the snow. It is very well known to men 

 living in the north that the ice on the lakes is certain to be wet, and that 

 travel over them is unpleasant and even dangerous for a long time, if 

 there has been a very heavy fall of snow soon after the ice has first formed. 



A good illustration of these conditions was seen on Gowganda Lake, 

 where the ice had attained a thickness of about twelve inches. There 

 had been a heavy fall of snow which had accumulated to a depth of from 

 two to three feet in the surrounding forest, and as there had been but 

 little wind accompanying the snow, it might have seemed reasonable to 

 look for a similar depth on the lake. But ice a foot thick will not support 

 the weight of two feet of dry snow, and consequently it had been pressed 

 down into the water, so that while it was completely covered to a depth 



