358 Astronomical and Nautical Collections. 



3. Add together the logarithmic secant of h, the sine of d, 

 the cosecant of At — s, the constant logarithm 9.6990, and the. 

 proportional logarithm of the horizontal parallax : the sum will 

 be the proportional logarithm of the diminution of parallax, 

 which is to be subtracted from the parallax in altitude, in 

 order to obtain the parallactic correction. 



4. To the logarithmic sine of the moon's altitude m, add the 

 proportional logarithm of the parallactic correction, and sub- 

 tract the sum from that of the horizontal parallax, the difference 

 will be the tangent of the refractional distance for the moon. 

 Find the refractional correction for this angle, and for its differ- 

 ence from the observed distance, as zenith distances, in the table 

 of refractions . 



5. When the distance d is small, add together the propor- 

 tional logarithms of the diminution of parallax, and of the sum 

 of the parallactic correction (3) and the parallax in altitude (2), 

 the logarithmic tangent of d, and the constant logarithm .5870 : 

 the sum will be the proportional logarithm of the correction for 

 obliquity. 



EX.AMPLE. 



1. Taking d again = 43° 36', in = 9° 38', j =: 11° 17', 

 j> = 54' 42", and its P. L. 5173, we have h — 32'' 15f , 

 A — « = 20° 58f , and A - w = 22° 37f . 

 2. P.X./) = -5173 4. Log. sin. ?7i 9.2236 



Log. sec. m .0612 P. L. 5' 54' 1.4844 



But 5' 54" — (37 + 10" +■ 26') = 4' 41 ', as before. 



