92 



Result adopted — Chronometer No. 2557, fast of si- h. m. s. 

 dereal time for this station (at I5h. 40m.) + 1 33 36.47 



This determination of the time, 1 consider very satisfactory. The 

 difference between the results by the East and West Stars, is, in each 

 set, very nearly correspondent with the known rate of the chrono- 

 meter during the elapsed time; which shows that the total arc mea- 

 sured in each case was actually what the limb of the sextant, after 

 applying the measured index error, reported. Hence the 14 alti- 

 tudes of the star Polaris, observed for the latitude, probably gave a 

 pretty close result, independent of a south star for eliminating errors 

 of observation. 



Sd. The Longitvde. 



From the time-observations made at Chicago, on the 6th and lOlh 

 of June, and those of the Sth, at Niles, and the telegraphic signals of 

 the Sth, we derive the longitude, as follows, viz. — 



Determination of the difference of Longitude between Chicago and 

 Niles, Michigan, by electric signals for comparisons of time, 

 June Sth, 1859. 



Sidereal Chronometer No. 2557, fast, of Niles sidereal liri.e (at 

 16/i. 46m. 37s. sidereal time), Ih. 33m. 36s.78. 



ilate per sidereal day, + 6.'?.6688; or per sidereal hour, + Os.2778. 



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

 time (at ll/i. 32m. 56s. mean time), 4m. 45s.72. 



Rale per mean solar day, — Os.443; or per mean solar hour, — 

 Os.01845 



1st. — Chicago signals recorded at both stations. 



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



05 28.375 



