146 Stria and Furrows of the Rocks of Western New York. 



in the phenomena of tornadoes and hurricanes. Beyond the 

 sphere of the alleged gyration, there is but little if any atmos- 

 pheric commotion, and certainly none competent to be the cause 

 of a great whirlwind. It follows that pigmy whirlwinds and 

 hurricanes can have no analogy. The former are never produced 

 without a proportionable external activity in the wind, while 

 comparative external quiescence seems to accompany the latter. 



128. I will conclude by applying to Prof. Dove the stricture 

 which I applied, on a former occasion, to Espy, and to Redfield. 

 He has, I think, committed a great oversight in neglecting to take 

 into consideration the agency of electricity in the generation of 

 storms. 



Art. XV. — Strice and Farrows of the Polished Rocks of West- 

 ern New York ; by Prof. C. Dewey. 



Two varieties of limestone underlie the grounds of Rochester 

 and its vicinity. The principal one is the calciferous slate of 

 Eaton, the limestone associated with the Rochester shales in the 

 geological reports of the State. The other lies upon the pre- 

 ceding over a small extent, forming a stratum a part of a mile 

 wide, and is the geodiferous limestone. Wherever the upper 

 surface of these is found polished, viz. over a considerable por- 

 tion of several square miles, the polish is marked by striae and 

 furrows of very variable depth and width and distinctness. 

 These have attracted some attention, and it may perhaps sub- 

 serve the interests of geology, to give some of their directions 

 and appearances, and refer to the cause of them. 



The stria; and furrows are intermingled without any regular- 

 ity. Sometimes several occur in an inch : at others, few or none 

 m such a space ; sometimes a dozen or more large and small in 

 passing over eighteen or twenty inches. They are now* very 

 fine, now coarse ; now shallow, then deep. Their directions vary 

 considerably ; some of them greatly. I have laid the compass 

 upon many in many different localities, and taken the bearing 

 •with considerable care. 



1. On an uncovered portion of the polished surface below the 

 falls of the Genesee in this city, the directions of some are very 

 nearly S. W. ; of others, S. 56° W., S. 64° W., S. 22° W., and 



