18. 



ON THE CORRECTIONS TO BE APPLIED TO BURCKHARDT'S AND PLANA'S 

 PARALLAX OF THE MOON, EXPRESSED IN TERMS OF THE MEAN 

 ARGUMENTS. 



[From the Monthly Notices of the Royal Astronomical Society, Vol. xin. (1853).] 



IN the Supplement to the Nautical Almanac for 1856, I have given new 

 tables of the Moon's parallax, adapted to Burckhardt's form of the argu- 

 ments. When the arguments have been already computed, these tables 

 supply the most convenient means of finding the parallax, and they have, 

 accordingly, been used in calculating the corrections to the Nautical Almanac 

 Parallaxes since 1840, given in the paper above referred to. 



When, however, Burckhardt's arguments are not previously known, it 

 will be more simple to employ arguments increasing proportionably to the 

 time, in order to calculate either the parallax itself immediately, or the 

 correction to be applied to that found from Burckhardt's tables. 



The following formulae may be used for this purpose, the arguments 

 being expressed in Damoiseau's notation. 



