83 



In Captain Andrew Talcott's report on the Ohio and Michigan 

 boundary, made in January, 1834, he gives the position of Fort Arm- 

 strong to be in latitude 41° 31' 09".7 N., and longitude 90° 27' 15"*- 

 = in time to 6h. 01m. 49s., exceeding us in the latitude, say 10", 

 and falling short of us in the longitude 26s.55 in time = 6m. 38s.25 

 in arc = 5.736 miles. 



On Nicollet's map, the lower extremity of Rock Island (occupied 

 by Fort Armstrong), is laid down 1' 20" in latitude less, and 8' of 

 longitude, = 6.91 miles more than our observations indicate. On 

 the last War Department map (of 1857), it is laid down in latitude 

 35" of latitude south, and 5' 24" in longitude west of the position given 

 by our observations. 



XIX. DAVENPORT, IOWA. 



This beautiful city occupies the height and slope of an eminence, 

 on the right bank of the .Mississippi river, immediately opposite to the 

 City of Rock Island, Illinois. 



A mean, derived from courses and distances measured on Stoddard's 

 map of 1851 , and Hogane & Lambach's mnp of 1857, mentioned be- 

 fore, and referred to our astronomical station XVII., gives us as fol- 

 lows, in regard to Davenport, Iowa, viz. — 



On Nicollet's map, Davenport is placed 18" in latitude south, and 

 7' 37" in longitude west of our position, derived from the preceding 

 observations. 



On the War Department map of 1857, it is placed 16 seconds of 

 latitude south, and 6 minutes and 5 seconds of longitude west of the 

 position which our observations assign to it. 



* Erroneously printed 90° 26^ 15''^ in his report, as contained in Doc. 

 No. 497, of the House of Representatives, 23d Congress, 1st Session. See 

 page 6 of that document. 



