SPECIMEN OF FORM No. 20. 



(13) 



{Continued from 1st paye.) 



Effects of Changes of R.A., of N.P.D., and of Time, on the Distance 

 between Centers. 



Half Sum (above) + , 



Log. sine <t> (above) 



Sum = log ( 



f = Factor of Change of R.A. for Distance between Centers (si<m as 1 

 for Excess of R.A.) ......./ 



Log. Increase of Excess of R.A. in 1'. (always ) 



Sum with log. f = log. it ( near beginning, 4 near end) 



rj (to 0"-0001) 



Log. cosine <t> (above) 



Nat. cos. q> = Factor of Change of N.P.D. for Dist. betw. Cent, with 1 

 sign changed (always ) 



Log. Increase of N.P.D. in I 1 , (always ) 



Sum with log. cos. <t> = log. 9 (always +) + 



flto(0"-0001) 



1 



TI + 8 = Increase of Distance between Centers in I 1 



Effect of Change of Coefficient of Parallax on the Distance 

 between Centers. 



Log. ( (above) 



Log. -j-^j Parallax in R.A 



Sum = log. 



K (to 0001 ) 



Log. cos. <t> (above) with sign changed 



Log- -nhr Parallax in N.P.D 



Sum = log. A 



\ (to 0-0001) 



K 



+ \ = Increase of Distance between Centers for -i_ Increase of! 

 Parallax _ j- 



Signature of Computer. 



