380 



The mean of the two results was adopted for the mean period of 

 the two sets, which corresponds very nearly (witiiin half an hour) 

 with the mean period of the signals, and thus leaves but that length 

 of run of the sidereal chronometer between the period of getting its 

 error from observation, and the mean period of the signals. 



1858, July 6th. Oh ser -cations for the Time at Milwaukee Station 



No. 3. 



1st Set. Before the Telegraphic Signals. 



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



By 12 observations on a, Lyrce, east (at I5h. 39m.) 1 02 01.19 



By ]3 observations on a, Bootis, west (at IGh. 04w.) 1 02 00.15 

 1st Result — Before the Signals — Chronometer No. 

 2557, fast of sidereal time for Milwaukee station 



No. 3 (at 15h. 52m.) - - - + 1 02 00.67 



2d Set. After the Signals. 



Sidereal chronometer No. 2557, fast: 



By 5 observations on u. Coronse Borealis, west (at h. m. s. 



20A. 08m.) - - - - - 1 02 01.83 



By 5 observations on u Andromedoe, east (at 207t. 22m.) 1 02 00.94 



2d Result — After the Signals — Chronometer fast of 



sidereal time for this station (at 20/t. 15m.) H- 1 02 01.38 



Do. do. (at 15h. 52m.) before the signals, as 



above, - - - - - -f 1 02 00.67 



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

 dereal time for Milwaukee station No. 3 (at ISh. 

 03m.) July 6th, - - - - + 1 02 01, 



The above result for the time at Milwaukee, combined with the 

 Chicago time-observationsof July 5th and 7th, and applied to the fol- 

 lowing telegraphic signals, give us a fourth determination of the dif- 

 ference of longitude between Chicago and Milwaukee, entirely inde- 

 pendent of the other three, as follows, viz. 



