314 



Hence the dome of the Chicago City 

 Hall or Court House is west of the cen- 

 tre of the Quebec citadel, - - 1 05 42.43 -fl 05 42.43 



Longitude of the dome of the City Hall or Court 

 House of Chicago, west of Greenwich, - - 5 50 32.08 



I will remark that the longitude of the citadel of Quebec is given, 

 under the authority of Bayfield, in the Connaissances dcs Temps for 

 the year 1842, and in the subsequent numbers, as h. m. s. 

 west of Paris, 4 54 26 



Difference allowed at the time for reducing from 

 the meridian of Greenwich to that of Paris, + 9m. 

 21s.5, and hence to reduce back to Greenwich, - — 9 21.5 



Bayfield's longitude of the citadel of Quebec, west 

 of Greenwich, 4 45 04.5 



Graham's determination of the longitude of the 

 same point in 1842, 4 44 49.65 



Difference of determinations, Bayfield west of Graham, + 14.85 



The latitude of the centre of the citadel of Quebec was observed 

 by me in the year 1842 (see the American Almanac for 1848, pp. 

 368, 369), with portable instruments, to be 46° 48' 17". 3 N. 



It is stated in the Connoissances des Temps, 

 from 1842 to the present time, under the authority 

 of Bayfield, at 46° 49' 12" 



Difference, Bayfield north of Graham, - - -f 54".7 



The American Almanac had adopted Bayfield's latitude and longi- 

 tude of this position in its general table, previous to my contribution 

 to that work published in the number for the year 1848; and since 

 that time it has continued Bayfield's determination in preference to 

 mine. I should be pleased, however, if the Society should think pro- 

 per to notice this paper, giving the results of my observations, made 

 in 1842, in its proceedings. 



The Latitude of Chicago. 



I was induced, in January last, to make a few observations, with 

 portable instruments, for ascertaining approximately the latitude of 

 the Ciiy Hall or Court House of Chicago. The instruments used 



