1835.] OcctdtatiGiis cf stars at Madras. 299 



Earth when the hour angle is -/-and later when +, there- 

 fore to determine the apparent hourly motions at appa- 

 rent conjunction assume two instants ; first the time of 

 true conjunction in right ascension and the 2d + or — 

 one hour from the first according to the sign of the hour 

 angle ; compute the Parallax in right ascension and 

 declination at these two instants. 



Then making 

 A=the Moon's right ascension at 1st instant. 

 D=the Moon's declination at 1st instant. 

 a=the true hourly motion in right ascension. 

 d=the true hourly motion in declination, 

 a' the apparent hourly motion in right ascension, 

 d' „ in declination, 



—when proceeding to the north and 4- when to the south. 

 A==the difference of declinations at conjunction. 



apparent difference of declinations at apparent con- 

 junction -h when the Moon is N and — when south of 

 the star. 



p'=:the parallax in right ascension at the 1st instant. 

 p"= at the 2d instant. 



P in declination at the 1st instant. 



P'= at the 2d instant, 



trrrthetime from the true to the apparent conjunction. 

 A + p'=^the apparent right ascension at the 1st instant. 

 A 4- a -f p" 2d instant. 



a'=^a + p'' — p* —apparent hourly motion in right ascen- 

 sion similarly. 



d'—d-fP' — P'—apparent hourly motion in declination; 



The difference of the apparent right ascensions of 

 the Moon and star at the 1st instant will be p', and t the 



time of the Moon describing this space will be t=i^-i::r 



a 



a + p'— p' 



