(12) 



TRANSIT OF VENUS, 1874. APPENDIX. 



[FORM No. 20.] [PAGE 



BRITISH EXPEDITION FOR OBSERVATION OF THE TRANSIT 



OF VENUS, 1874. 



COMPUTATION OF TABULAR LOCAL DISTANCES BETWEEN THE CENTERS OF THE SUN AND 

 VENUS, AND OP FACTORS OP CORRECTIONS TO TIME, R.A., N.P.D., AND PARALLAX. 



(The quantities are entirely Tabular Local quantities. " Excess of R.A." always denotes "Excess of Tabular 

 Local R.A. of the Center of Venus above that of the Sun." " Excess of N.P.D." always denotes " Excess of Tabular 

 Local N.P.D. of the Center of Venus above that of the Sun." " Parallax " [meaning Horizontal Equatoreal 

 Parallax], " Parallax in R.A.", " Parallax in N.P.D.", always denote " Excess of those quantities for Venus above 

 the similar quantities for the Sun." The same applies to the several " Increases." The S.P.D. of Sun and Venus 

 are, however, absolute values. " Distance between Centers " denotes " Tabular Local Distance between Centers." 

 All logarithms are to be taken to five decimal places. To six places for " Distance between Centers.") 



Station. 



No. of Observation in Form 17. 



S.P.D. of Sun (to 10") . . 

 S.P.D. of Venus (to 10") . 



Excess of Right Ascension (to 0"-01) (+ near beginning, near end) 

 Increase of Excess of Right Ascension in 1". (to 0"-001) (always ). . 



Excess of North Polar Distance (to 0"- 01) (always -) 



Increase of Excess of North Polar Distance in 1". (to 0"' 001) (always ) 



Parallax in R.A. . . 

 Parallax in N.P.D. 



Computation of Tabular Local Distance of Centers of Sun and Venus. 



Log. sine of S.P.D. of Sun . . 

 Log. sine of S.P.D. of Venus 



Sum 



Half Sum (always + ) 



Log. Excess of R. A. ( + near beginning, - near end) 



Sum = f (sign same as for Excess of R.A.) 



Subtract log. Excess of N.P.D. with sign changed (always + ) 



Log. tan. <t> (sign same as for Excess of R.A.) 



<l> (to 10") (less than 90, sign same as for Excess of R.A.) 



Log. sine <f> (sign same as for Excess of R.A.) . 

 Subtract from f (sign same as for Excess of R.A.) . 



Log. Distance between Centers (always + ) 



Log. cosine </> (always + ) 



Subtract from log. Excess of N.P.D. with sign changed (always + ) 



Log. Distance between Centers (always + ) 



Distance between Centers (to 0"-01). 

 (Continued on 2nd page.') 



