375 



Determination of the difference of Longitvde befu'een Chicago and 

 Milwaukee, by electric signals for comparisons of time, July 

 1st, 1858. 



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

 (at 17/t. ISm. 48s. sidereal time,) Ih. 01m. 32s.47. 



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



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

 time, (at 10^. 4077z. 125. mean time.) Am. 52s. 27. 



Rate per mean solar day, + 0s.90 ; or per mean solar hour, + 

 Os.0375. 



1st. — Chicago signals recorded at both stations. 



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



01 06.54 



2d. — Milwaukee signals recorded at both stations. 



2d Mean. — Electric signals sent from Milwaukee to Chicago, 01 06.545 



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



above, _ . - . . - 01 06.540 



Result : — The centre of the Court House Square at Milwaukee, is 

 west, in longitude of Chicago, observing Station No. 3, by a 



mean of the two sets of signals, 



+ 01 06.54 



