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THE POPULAR SCIENCE MONTHLY. 



breaking in upon its structure, floating off its ice-fragments in 

 the form of bergs or floes, and, by releasing at the same time 

 its heavier rock and gravel . constituents, built up a breakwater 

 which, as an island, now forms what is known as " Fisher's Island 

 Sound." Fig. 2 represents a not unfrequent example of the char- 



acter of the materials which enter into the construction of this 

 natural breakwater, as seen from the western side of this island. 



But it is in the region to the east and west of the line of the 

 Thames River, and which it has been suggested may have been 

 the axis of the ancient glacier, and not very far removed from 

 this line, that bowlders of extraordinary size occur most numer- 

 ously ; and among them is a rock which until very recently has 

 been regarded as one of the largest, if not the very largest, bowl- 

 der that has thus far been recognized in this or any other coun- 

 try. This rock — of coarse crystalline granite — is situated in the 

 town of Montville, New London County, about six miles south of 

 Norwich, and about a mile west of the Montville Station on 

 the New London and Northern Railroad ; and, under the Indian 

 name of ' Sheegan," has almost from the first settlement of the 

 country been recognized as a great natural curiosity. Its posi- 

 tion is on the edge of a gentle mound or knoll, on the northeast 

 slope of a little valley ; and its dimensions, according to recent 



