-1830] WRITINGS OP JOSEPH HENRY. 25 



From Lake Erie to the head of the rapids distance 20 miles, fall 15 feet. 



Thence to the falls 1 61 



The falls .. 164 



From the falls to Lewiston, at the mouth of 



the chasm 7 104 



Thence to Lake Ontario 7 2 



Total 35 miles, fall 33G feet. 



The annexed table of elevations and distances, through 

 the whole extent of the St. Lawrence basin, in connexion 

 with the tables already given, will show its depression below 

 the mountain surface of the country. 



No. XI. — Table of Ascents and Distances through the St. Lawrence basin, 

 from the Gulf of St. Lawrence to the western angle of Lake Superior. 



The slopes of the lower subdivision of the St. Lawrence 

 basin, which descend to the shores of Lake Ontario, occupy 

 a considerable portion of the state of New -York. Begin- 

 ning near the eastern extremity of Lake Erie, the boundary 

 or edge of this sub-basin may be traced on the map along 

 the heads of streams falling into Lake Ontario, thpough the 

 southern part of the counties of Erie and Genessee, to the 

 valley of the Genessee river, which is an arm of the St. Law- 

 rence basin, stretching up into the high lands of Pennsyl- 

 vania. From the Genessee river, the edge of the basin 

 curves to the southeast around the southern extremities of 

 Seneca and Cayuga lakes, including the four smaller lakes 

 which lie a little to the west of these. The deep ravines in 

 which are situated Seneca and Cayuga lakes may also be 



