REPORT ON 



Double Altitudes of the Sun for Time, observed at Ceara, Brazil, December 14th, 1865. 



5I m 



5i" 



100° 



5° 



52 



14-5 





40 



52 



37 





30 



53 



i-5 





20 



53 



26 





10 



56 







98 







56 



23 



97 



5° 



56 



48 





40 



57 



"•5 





3° 



57 



34 





20 



Index correction. 



20 



2O 



359° 



10' 



5°" 



o° 



15' 



So" 







40 





lb 



20 







20 





16 







359 



10 



36-7 







16 



3-3 



Correction = + 16' 40". o 



Ex. ther. 86° 

 Refraction = — 45". 6 

 Parallax = + 5.6 



At. ther. 83 Bar. 30.00 inches. 



Sun's declination — 23° 15' 27". 4 



Mean of observed double altitudes 

 Mean of chronometer times 

 Equation of time 



99 



5 



54* 

 4 



42 s . 6 

 53-7 



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

 2 h 26 m 30 3 .7 slow of local mean time. Reducing it with latitude = — 3° 44' 15", 

 we find the chronometer 2 h 26 m 33M slow of local mean time. 



In order to determine both the latitude of Ceara and the error of the chronometer 

 from the three observations which have just been given, we proceed as follows: 



Comparing the error obtained on the afternoon of December 13th, with that 

 obtained on the afternoon of December 14th, we find that the chronometer was 

 losing 1.17 seconds per day; and this rate is independent of any small change in 

 the adopted value of the latitude. 



By means of this rate, reducing all the observed chronometer errors to 2 b 26 m 

 P. M. December 14th, and then plotting them according to Sumner's method, we 

 get for the place of observation 



Latitude 3° 43' 59" S. 

 vmd for the chronometer, 



Chronometer slow of local mean time . . - . . 2 h 26 m 32 s .5 

 Longitude west . . . . . . . . 2 34 6 



Chronometer slow of Greenwich mean time . . . . 5 o 38.5 



Double Altitudes of the Sun for Time, observed at Pernambuco, Brazil, December 23d, 1865. 



3° m 15 s 





118° 



3° 39-5 







3 1 3 







32 52-5 





118 



33 15 







33 4o 







Ex. ther. 



83° 



Refraction 



= — 3 2 "- 



Parallax 





= + 4-5 



30 



3° 



2© 



2© 







Index 



correction 







359° 



10' 



5°" 

 5° 





o° 



16' 

 16 



0" 

 10 



359 



10 



50.0 









16 



5-o 



At. ther. 



Correction = + 16' 32".5 



Bar. 

 Sun's declination — 23 26' 31" 

 Latitude — 8 3 37 



Mean of observed double altitudes ..... 118° 20' o".o 



Local apparent time . . . . . . . io h g m 3°. 5 



Equation of time ....... . — o 31.2 



Local mean time ........ 10 8 32.3 



