378 



Determination of the difference of Longitude between Chicago and 

 3Iihcaiikee, by electric signals for comparisons of time, July 



Sd, 1858. 



Sidereal Chronometer No. 2557, fast, of Milwaukee, sidereal time^ 

 (at 8/t. 00m. 47s. sidereal time,) \h. Olm. 41s.01. 



Rate per sidereal day, + 5s.66 ; or per sidereal hour, -\- 05.236. 



Mean Solar Chronometer No. 141, slow, of Chicago, mean solar 

 time, (at Ih. 15m. 51,5. mean time,) 4m. 51s.06. 



Rate per mean solar day, + 05.90 ; or per mean solar hour, 4- 

 05.0375. 



1st. — Chicago sicnals recorded at both stations. 



1st Mean. — Electric signals sent from Chicago to Milwaukee, 



01 06.30 



2d. — Milwaukee siiznals recorded at both stations. 



2(1 Mean. — Electric signals sent from Milwaukee to Chicago, 01 06.29 



1st Mean. — Electric signals sent from Chicago to Milwaukee, as 



above, - - - - - - - 01 06.30 



Result. — Milwaukee observing Station No. 3 is west, in longitude 

 of Chicago observing Station No. 3, by a mean of the two 

 sets of signals, - - - - - -f- 01 06.3 



