On the Polished Limestone of Rochester. 



243 



repeated only twice. The water was a little colder in 1838 than 

 at the same time in 1837. The following are the observations. 

 They were made at each shore, and from five to seven miles dis- 

 tant across the lalie, by the same individual, Mr. McAnslan. 



American shore in the morning. 



In 1837, about the middle of 

 September, the temperature of 

 the lake was about 60° at most of 

 the points across it. On Oct. 16th, 

 it was colder at the shore than 

 in the middle of the lake. 



Coburg on the Canada shore. 



The mean temperature of the 14th at Rochester, was 59° 

 " " 21st " 72 



It is hardly necessary to remark that the observations were 

 taken from the mouth of the Genesee, in a nearly direct line to 

 Coburg on the Canada shore. The influence of so great a body 

 of water as that of Lake Ontario, at so low a temperature as 36°, 

 or only 4° above the freezing point in the middle of May, must 

 be palpable on the adjacent country. 



