PLACES IN THE STATE OF OHIO, ETC 273 



is only an approximation, by admeasurement, of a map supposed to be 

 accurate. 



It appears from these observations, and those that have been made 

 in the Atlantic cities, that although the lines of equal dip, in travelling 

 from Britain vy^estwardly, decline rapidly to the south, yet they attain 

 their greatest southing before they reach our continent, for we find 

 them, on the whole, in passing from the Atlantic to Ohio, proceeding 

 rather north of west. The line of dip equal to that of Philadelphia, 

 latitude 39° 57' N., would pass through the western part of Ohio, in 

 latitude 40° 43' N. ; still, in Ohio itself, these lines are again declining 

 to the south ; for the line of equal dip of Columbus, in latitude 39° 57', 

 would cross the meridian of Cincinnati, in latitude 39° 27', declining half 

 a degree of latitude in 1° 27' of longitude. It is my intention to extend 

 these observations over as large a portion of the western states as pos- 

 sible. The results, together with those for determining Intensity and 

 Declination, I hope to be able to communicate to you at an early 

 period. 



Very respectfully. 



Your obliged friend, and 

 Humble servant, 



JOHN LOCKE. 



Cincinnati, May 7, 1838, 



