Bi Mr. Baily's proposed Tables Jbr the 



come. For, since the place of the sun's perigee in 1830 will 

 be exactly 280°, and since it varies only 62" from year to 

 year, a table of the equation of the centre computed for the 

 first 90° of the sun's mean anomaly will answer for the whole 

 circle : attention being paid to the signs. Let z denote the 

 mean anomaly of the sun for the yeai* 1830, then will the 

 equation of the centre be 



+ 1° 55' 22",81 sin 2 + 72",61 sm 2z + l",06 sin 3z 



7. Having thus determined the tnie longitude of the sun, 

 for each star, on every tenth sidereal day of the fictitious year, 

 we much enter Mr. Herschel's tables with the Arguments 



(O + N) and (2© + N") 



and find the respective values of the quantities required. The 

 values of N and N" are given by Mr. Herschel*. 



8. With respect to the precession, or rather the annual 

 variatiofi, its amount at any given moment of time will be ex- 

 pressed by L— ^sio 



^ 360° 

 where V denotes the annual variation, and L the mean longi- 

 tude of the sun as above determined t. If we substitute the 

 value of L for each star, and make the proper reductions, 

 this formula will become J 



V X (-00273 «— -00213) + 



a being, as before, the right ascension of the star, converted 

 into the decimal part of 24''. These values being added to 



* As an example, take the case of u AquiLe on the tabular April lltb. 

 The true longitude of the sun on that day, at the time of the culmination 

 of the star, will be 19° 20' 6" + 1° 53' 27" = 21° 13' 33". Consequently 

 by Mr. Herschel's tables the amount of the aberration in right ascension 

 will be -0'-0600; and of the solar-nutation — 0'-0536. 



j- Mr. Herschel's Table 1. gives the annual variations for mean solar 

 days, and not for sidereal days. 



J As an example, take the case of « AquiUe, whose annual variation 

 (in right ascension) is equal to 2"924 ; the proportional part of which, on 

 January 1, at the time of its culmination, will be + 2*"924 (-00224 — 

 •00213) = +0'-00032: which being added to 0'-0798, and its multiples, 

 will give the amount of the annual variation at the time of its culmination 

 on every subsequent tenth sidereal day of the year. Thus, on the tabular 

 April nth, it will be +0'79o3. 



the 



