387 



Determination of the difference of Longitude between Chicago and 

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

 July 20th, 1858. 



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

 ISh. 16m. sidereal time), + Ih. 09m. 14s.2. 



Rate per sidereal day, + 55.39. or per sidereal hour, + Os.2245. 



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

 time (at lOh. 28m. mean time), 104771. 425.16. 



Rate per mean solar day, + 05.42. or per mean solar hour, + 

 05.017. 



1st. — Chicago signals recorded at both stations. 



1st Mean. — Electric signals sent from Chicago to Madison, Wis., 07 00.818 



2d Mean. — Electric signals sent from Madison, Wis. to Chicago, 07 00.84 

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

 consin, as above, 07 00.818 



Result : — Madison Station No. 2, west, in longitude, of Chicago 



observing station Ko. 2, by a mean of the two sets of signals, + 07 00.83 



