101 



meter error can be depended on to-night, nearer than one second of 

 time. However, as this, even, affords a desirable approximation to 

 the true longitude of Cleveland, we think it may be well to report the 

 result. It depends on the time-observations for this night at Cleve- 

 land, above given, those at Chicago given under the dates of August 

 4th and 12tli, 1858, and the following telegraphic signals, viz. — 



Determination of the difference of Longitude between Chicago and 

 Cleveland, by electric signals for compai'isons of time, August 

 5th, 1858. 



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

 (at 22h. 18m. 47s. sidereal time), 40m. 096-.61. 



Rate per sidereal day, -f 5s.58; or per sidereal hour, + Os.232. 



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

 time (at \2h. 57m. mean time), 4m. 31s.46. 



Rate per mean solar day, + Os.455; or per mean solar hour, + 

 Os.01896. 



1st. — Chicago signals recorded at both stations. 



1st Mean. — Electric signals sent from Chicago to Cleveland, 23 42.056 



