i i 



2d Result — Chronometer fast (at 8h, h. m. s. 



I5m.) - - - 1 38 38.42 h. m. §. 



+ 1 38 3S.42 



Result adopted— Chronometer No. 2557, fast of si- 

 dereal time for this station (at Ih. 31ot.) H- 1 38 38.27 



Having so good a determination of the ti7ne by this night's observa- 

 tions, it was a great disappointment, when we went to the telegraph 

 office, to find the communication with Chicago cut off at La Salle, 

 througli some misunderstanding there. We were thereby prevented 

 from passing any electric signals this night, but were obliged to wait 

 until the next night. 



1859, March Isi. Same Station. 

 Sidereal chronometer No. 2557, fast: 

 By 8 observations on « Leonis, east h. m. s. 



(at 6^. 34m.) - - 1 38 42.18 



By 9 observations on y' Leonis, also 



east fat Ih. 04;«.) - - 1 38 42.22 



By 17 observations on 2 East Stars (at h. m. s. 



6h. 4.9m.) - - 1 38 42.20 = -f 1 38 42.20 



By 13 observations on a, Tauri, west (at 8/t. lo/w.) -f 1 38 42.21 



Result — Chronometer No. 2557, fast of sidereal time 



for this station, (at 7h. 32w.) - + 1 38. 42.20 



The above observations for the time at the City of Rock island, on 

 the. nights of February 28th, and March 1st, give the rate of chrono- 

 meter No. 2557, for the 24 hours between those dates, + 35.93. This 

 rate applied to the period of the chronometer error of the 1st of March, 

 together with the time observations made at Chicago on the 27lh of 

 February and the 4th of March, and the following telegraphic signals, 

 give us the longitude of our "City of Rock Island" station. 



Although we returned from Rock Island to Chicago on the evening 

 of March 2d, yet the weather continued so cloudy until the night of the 

 4th, as to prevent our making earlier observations for the time here. 



Thus we have to depend upon five days run of chronometer No. 

 141, to obtain its rate to be applied to the observations of February 

 27th, in order to get the Chicago mean solar time of the signals of the 

 1st of March. 



