MAGNETIC OBSERVATIONS. 



17 



Chronometer slow of local mean time. 

 Longitude west ...... 



Chronometer slow of Greenwich mean time 



i 3 o ra I 9 ".4 



3 3 IT -4 



5 



30.8 



Double Altitudes of the Sun for Time, observed at Ceara, Brazil, December i$th, 1865. 



Index correction. 



Correction = + 16' 33". 3 



Ex. ther. 84 At. ther. 82 Bar. 30.05 inches. 



Refraction = 89". 5 Sun's declination 23 12' 4".o 



Parallax = + 7-4 



Mean of observed double altitudes 

 Mean of chronometer times 

 Equation of time 



62 18' o".o 



20 -9 



Reducing this observation with latitude = 3 43' 15", we find the chronometer 

 2 h 26 m 29 3 .6 slow of local mean time. Reducing it with latitude = 3 44' 15", 

 we find the chronometer 2 h 2(?' n 32 s .O slow of local mean time. 



Double Altitudes of the Sun for Time, observed at Ceara, Brazil, December \tfh, 1865. 



Index correction. 



Ex. ther. 81 

 Refraction = 45"-9 

 Parallax = + 5-6 



At. ther. 82 



Sun's declination 



Correction = + 16' 33". 3 

 Bar. 30.12 inches. 



Mean of observed double altitudes 

 Mean of chronometer times 

 Equation of time 



23 14' \d".t 



IOO" 10 O .0 



7" 4 ra 5 2'- 8 

 - 4 59-5 



Reducing this observation with latitude = 3 43' 15", we find the chronometer 

 2 h 26 m 33 9 .7 slow of local mean time. Reducing it with latitude = 3 44' 15*, 

 we find the chronometer 2" 26 m 30 3 .9 slow of local mean time. 



February, 1872. 



