349 



Catholic Church, which was occupied in May, 1857, for determining 

 the difference of longitude between this place and Quebec; for an ac- 

 count of which see pp. 12 to 21, and 56 to 60, of Senate (Executive) 

 Documents No. 42, of the 35th Congress, 1st Session. 



By triangulation, based, for orientation, on the true meridian line 

 determined with the astronomical transit in May, 1857, we find that 

 our present station, which I call Chicago observing station No. 3, is 

 4,059.49 feet north of the parallel, and 1,027.16 feet east of the me- 

 ridian of the centre of the dome of the City Hall or Court House of 

 Chicago, equal to 40". 11 difference in latitude, and 13". 6 of arc=0.9 

 of a second of time, difference in longitude.* 



Observations for the Latitude of Chicago. 



1st. 1858, Avgvst loth. Station No. 3. 



Time stars «« AndromedcE east, and cc Coronse Bo- 

 realis west. Also, equal altitudes of a Cygni. 



Latitude of Station: 



By 25 circum-meridian altitudes of <t Aquilse (Altair) 

 S., combined with 17 circum-meridian altitudes 

 ofyCephei,N 41° 53' 46".8 



2d.— Same Night. 

 Latitude of Station. 

 By 12 circum-meridian altitudes of c* Aquarii, S. com- 

 bined with 10 altitudes of Polaris, (<* Ursse Mi- 

 noris)N., 41" 53' 45".6 



Sd. 1858, Avgvst 23d. 

 Time stars the same as on the 15th. 



Latitude of Station: 

 By 24 circum-meridian altitudes of a. Aquila3, S., 

 combined with 18 circum-meridian altitudes of 

 y Cephei, N., 41° 53' 47".3 



Note, There was still another observing station, called Chicago observing 

 station No. 2. As I shall have occasion hereafter to refer to its position in 

 longitude for chronometric comparisons with other places, 1 may as well here 

 mention that it is 24 feet=0^^ 24 north of the parallel, and 179 feet=2^^.37 

 of arc, or 0.16 of a second of time west of the meridian of the 1st. observing 

 station, or that of May, 1857. 



