44 



By comparison — Chronometer No. 141 was slow of 



mean solar time (or this station (at 9A. 15m. mean h. m. s. 

 lime) • - - - - - — 5 01.76 



F. S. The following determinations of the Chicago time (Nos. 29 

 and 'M)) were made after this paper was presented, with reference to 

 a second determination of the longitude of the City of Rock Island, 

 viz: — 



29th. I'^.dO, July 2^fh. At Chicago Station Ao. 8. 



Sidereal chronometer No. 2557, fast : //. /u. s. 



By 13 observations on s Bootis, west (at 17/i. 44/«.) + 1 45 30.94 

 By 15 observations on <f Cygni, east (at I8h. 06m.) + 1 45 31.40 



Result — ('hronometer No. 2557, fast of sidereal time 



for this station (at 17/i. 55m.) - -|- 1 45 31.17 



By com,parison — Chronometer No. 141, was slow of 

 mean solar time for this station (at 9h. 30m. 

 mean time) - - - - - — 5 03.37 



30/^. 1859, July 'Slst. At the same Station. 

 Sidereal chronometer No. 2557, fast: h. m. s. 



By 10 observations on ^ Cygni, east (at llh. 45m.) -|- 1 45 53.86 

 By 10 observations on e Bootis, west (at 18//.. Olm.) + 1 45 54.13 



Result — Chronometer No. 2557, fast of sidereal time 



for this station (at 17A. 53?/^.) - + 1 45 53.99 



By comparison — Chronorueter No. 141, was slow of 

 mean solar time (or this station (at 9//. 16m. 

 mean time) - - - - — 5 05.63 



This ends the series of time-ohs(M'vations made at Chicago durinfr 

 the period included in this paper. 



Rates of the Chronometers. 



The rates of the chronometers during the period included in this 

 paper, were as follows, viz: 



