Elevations in Ohio and the adjacent States. 13 
Higgins, Esq., puts it at 565.333 feet. If this last number repre- 
sents the levelage of the Erie Canal, it is probably good for the 
surface of the Lake, as it was when the surveys were made for 
that work, twenty five years since. The surface, however, fluc- 
tuates in the extreme about six feet, thus rendering all measure- 
ments based upon the Lake as a starting point, liable to an error 
of that amount. The Ohio Canal was explored in 1824—5, and 
of course its elevations are noted with regard to the stage of water 
at that time. ‘The difference between 1816 and 1824 in the sur- 
face of the Lake, will render all our levels along the Ohio Canal, 
when referred to the ocean, inaccurate by that amount. Jn the 
latter part of the year 1815, and all of the year 1816, the Lake 
was iigh, about four feet above the point of greatest known de- 
pression. From 1819 to 1822 it was dow, and in 1825 was still 
but about two feet above the lowest known point. The error in 
adopting the Lake surface, in 1824, as a starting point, may there- 
fore be two feet, making its general surface above the tide-water 
at Albany, in 1824—5, 563 feet, and at the time of the great rise 
in June, 1838, 567 feet. In estimating the heights given below, 
Ihave used the commonly received number of 564, to express 
the surface of the Lake. Both upon the Erie and the Ohio canals 
and other works, the slopes sometimes given to the bottom are 
rejected, because unknown: where there is more than one sum- 
mit they counteract each other in some degree. Where there are 
fractional feet they are rejected. In some cases there are short 
intervals not measured, or the minutes of a portion of the heights 
are wanting, or the authorities are contradictory ; these are desig- 
nated by an interrogation, and will go for what they are worth. 
Information derived from so many sources, and transcribed many 
times from one note-book to another by different persons, must of 
course be subject to errors. But it has been drawn from the best 
authorities, viz. the profiles and reports of the engineers in the 
public employ. ‘ 
For location of points I have adopted Columbus, the capital of 
Ohio, in latitude 39° 57’ north, longitude 83° 3’ west, as the cen- 
tre of reference. The general course and distance from Colum- 
bus being given, the courses and distances of the different places 
among themselves may easily be found. 
The order of stratification in Ohio is as follows, beginning at 
the lowest of our explored rocks, the limestone. 
