118 



by telegraph after midnight of June 5th, give us another comparison 

 of longitude between the two places, as follows, viz. — 



Determination of the difference of Longitude between Chicago and 

 Madison, Wisconsin, hy electric signals for comparisons of time, 

 June 5th, 1859. 



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

 (at 17/t. 2ljn. 26s. sidereal time), Ih. 45m. 47s.37. 



Rate per sidereal day, + 6s.086 ; or per sidereal hour, + 05.2535. 



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

 time (at I2h. 2ljn. 55s. mean time), 47/i. 43s.63. 



Rate per mean solar day, — 05.20; or per mean solar hour, — 

 05.0083. 



1st. — Chicago signals recorded at both stations. 



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



07 01.647 



2d. — Madison signals recorded at both stations. 



2d Mean. — Electric signals sent from Madison to Chicago, 

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

 as above, ------- 



Result: — Madison Observing Station is west, in longitude, of 

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



07 01.657 



07 01.647 



of signals, 



- _ 07 01.65 



