58 



2d Mean. — Electric signals sent from Prairie du Chien to Chicago, 14 03.422 

 1st Mean. — Electric signals sent from Chicago to Prairie du Chien, 



as above, ---------- 14 03.436 



Result: — Prairie du Chien observing station is west, in longitude, 

 of Chicago observing station No. 2, by a mean of the two sets 

 of signals, - - -f 14 03.429 



Longitude of Chicago observing station No. 2, west h. m. s. 

 of the meridian of Greenwich, - - -f 5 50 31.15 



Longitude ofPraire du Chien ob.serving station, west 



of the meridian of Greenwich, 

 Equal, in arc, to - 

 Latitude of this station, as above. 



6 04 34.58 



91°08'38".7 W. 

 43° 02' 01". 35 N. 



The above determination will be found, we think, to correspond 

 very nearly with that of Mr. J. N. Nicollet, derived by him from obser- 

 vations made in the year 1839, while employed in ex[)loring the hy- 

 drographical basin of the Mississippi. His station was the American 

 Fur Company's house, near Fort Crawford. An interesting discus- 

 sion of the several observations which led him to the longitude which 

 he adopted for that station, will be found in his report at page 117, 

 of Senate Document No. 273, of the 26th Congress. 2d Session, 

 printed in the year 1843. 



He there states the longitude of that point to be, //. m. s. 



West of the meridian of Greenwich, - - 6 04 35.55 



Equal, in arc, to - - - 91° 08' 53".25* 



In his table of geographical positions, however, at page 123, he 

 states that position to be in 



Latitude - - . . 43° 03' 06" N. 



Longitude, west from Greenwich, - ijh. 04m. 37.35. 



^- Erroneously printed in tliat document, 93°, (S:c. 



