14 



REPORT ON 



Parallax 



Reduction to meridian 

 Sun's declination 

 Latitude 



+ i i9-4 



.19 6 59.1 

 1 8 20' o" N. 



Circummcridian Altitudes of the Sun for Latitude, observed at Isle Royal, Salute Islands, 



November 2&th, 1865. 



10" 13- 57'- 



U 35-5 



15 9-5 



15 5 3 



16 24.5 



i? i-5 



17 38 



18 14-5 



20 17 



21 9 



31 46.5 



3 2 30 



126 



5 3 



49 3 



49 3 



49 20 



48 50 



48 40 



52 10 



51 10 



48 20 



46 

 30 



26 50 



10 

 o 



Index correction. 



Correction = + 16' 25". o 



Ex. then 

 At. ther. 

 Bar. 



91 

 85 



inches. 



Mean of chronometer times 

 Chronometer slow o 

 Equation of time 

 Local apparent time 

 Mean of observed d 

 Index correction 

 Apparent altitude of 

 Refraction . 

 Parallax . 

 Reduction to meridian 

 Sun's declination 

 latitude 



Observations for time were usually made in such a manner as to eliminate both 

 the sun's semi-diameter and all errors which might be produced by the roof of the 

 artificial horizon. For full details of the method see page 33 of the " Reports on 

 Observations of the Total Eclipse of the Sun, August 7, 1869," published by the 

 U. S. Naval Observatory, Washington. 



The reduction of the observations for time has been effected by means of the 

 following formula?: 



a=- -_ r -f_p 



sn 



1 

 == i/sin (S a) cos S sec <p cosec d 



dt = t + r I 



T=. mean of observed chronometer times. 

 A = mean of observed double altitudes. 

 u = index correction. 

 r = refraction. 

 p = parallax. 



