1909.] Ice on Canadian Lakes. 13 



ICE ON CANADIAN LAKES. 



By J. B. Tyrrell, M.A., F.G.S., &c. 



(Read 20th November, 1909) 



Last week your president, in his address, complained that he had 

 been under the necessity of delivering two presidential addresses in two 

 consecutive years, but he is in an exceedingly comfortable condition 

 compared to the one that I find myself in, for in looking over the list of 

 six lectures to be delivered in this hall before next New Year, I see that 

 five are by professors whose business it is to talk impressively and accu- 

 rately for three or four hours a day and to whom an extra hour, more or 

 less, is mere added enjoyment, while I am placed in the middle of this 

 list of talkers and am expected to compete with them on even terms 

 though my business is to work and keep silence, for if I should say a word 

 about any mine that I had examined my reputation would be gone for 

 ever. 



Though mining is the most interesting subject to me and probably 

 one of the most interesting to the people of Ontario, as it is certainly one 

 of the most important to them, nevertheless we will step aside for a little 

 while and consider a subject that might occupy our attention profitably 

 and enjoyably through the coming winter. 



Most of us in Canada have opportunities for observing the formation 

 and character of the ice which covers our lakes during the winter, for 

 though Lake Ontario, on the shore of which we in Toronto live, is never 

 entirely covered with a coat of ice, Toronto Bay, which is a small and 

 almost isolated lake in itself, does freeze over, and the thousands of lakes, 

 large and small, scattered throughout Northern Canada, which are occa- 

 sionally visited by many of us, are covered every winter with solid ice 

 from shore to shore. 



It will be interesting for us to attempt to follow the method of for- 

 mation of this ice and any changes that may occur in it from time to time 

 from the beginning of winter until the bright sunshine of the long spring 

 days breaks it up and dissolves it into water again. 



First let us understand that ice is much lighter than water and floats 

 with great buoyancy on its surface. A cubic foot of water at 32°F. weighs 



