^54 Astronomicnl and Nautical Collections. 



from twice the proportional logarithm of the horizontal parallax 

 will give the proportional logarithm of the cbrrection for 

 obliquity. 



Note. If a table of proportional logarithms is not at hand, 

 we may take the common logarithm of the horizontal parallax 

 in seconds, and find from it the logarithm of the parallactic 

 correction by adding the logarithm of the difference (3) instead 

 of subtracting ; and in the fifth precept, add all the logarithms 

 together, employing 6.2370 for a constant factor, instead of 

 8.413. 



Example L 



Taking the case already constructed for an example, the 

 moon's proportional logarithm being 5173, the operation wilt 

 Btand thus : 



N. .1757 9.2448 



