242 On the Temperature of Lake Ontario. 



south; it does not underlie all of this area, because the surface is 

 not every where of this polished rock, but it may underlie no 

 small portion of it, and cover hundreds of acres. 



The surface of this polished rock is often marked with grooves, 

 as if a rough and heavy body had moved over it and left deep 

 traces. These are nearly parallel with each other, and on the 

 west side of the river are found to lie nearly from N. E. to S. W. 

 in the rock at the rapids. On the east side of the river below the 

 falls, the direction is but little different from the other, but some 

 degrees more towards the west. 



Such are the facts : what can be the cause ? The surface was 

 not made thus originally ; it has been done artificially, though by 

 nature, by some mighty power. The rock often presents the 

 same appearance as that of a hoard planed only on one edge or 

 towards one side. There is the same kind of evidence that the 

 one has been planed, and the other polished. There is on some 

 of the darker surfaces a glazed appearance, although nothing can 

 be removed from the stone without destroying the polish, and is 

 owing to the bitumen in the stone. To the eye the appearance 

 is, that it has been polished like our common marble, by the fric- 

 tion of a hard and smooth surface upon it. 



The friction of the water and earth in the Genesee wears some- 

 what smooth surfaces on the same rock, but nothing like the 

 polished surface now described. 



What is the power or cause which could have moved any hard 

 body so as to have produced this result ? 



It is said that the polished surface has been found over a much 

 larger district, but I have not the evidence to offer. 



Rochester, Aug. 9th, 1839. 



Art. V. — On the Temperature of Lake Ontario ; by Prof. 

 Chester Dewey. 



In Vol. XXXIII, p. 403, of this Journal, I gave some account of 

 the temperature of this lake during the warm months of 1837. 

 The results were so curious that I began to repeat them the next 

 year. The results so perfectly agreed, that the observations were 



