Astroiuymy. 181 



to the proposal and adoption of various corrections in the Solar Tables, 

 which it is presumed will lead to remove the discrepancies hitherto ob- 

 served. The following are some of the conclusions drawn from Mr Bessel's 

 investigations. They are calculated for the time of mean noon at Green- 

 wich. 



Mean. Long, of the Sun, January 1st 1801, 280° 39' 13",17 

 Long, of perigee - - - 27931-9,91 



Eccentricity - - _ .0167918226 



Mass of Venus - - - 40T847 



Mass of Mars - . „ , gg^oggy 



Sidereal revolution of the Sun, 365.256374417 = 



365** 6^ 9*" 10* 75 



Tropical revolution of the Sun, 365.242220013 = 



365^ 5^ 48" 47^ 1 

 The principal corrections therefore to be applied to the Solar Tables of, 

 Delambre, will arise from the alteration in the epoch of the mean longi- 

 tude, and in the longitude of the perigee, the former of which is increased 

 2". %b* and the latter ^6" . Professor Airy makes these corrections equal 

 to + 5".061 for the epoch, 1821.5 and + 46".3 for the perigee : each 

 measured from the equinoctial point adopted by Mr Pond in 1826. At the 

 same time, he states that the greatest equation of the centre ought to be 

 diminished 90". 84, the mass of Venus reduced in the proportion of 9 to 

 8 nearly, and the mass of Mars in the proportion of 22 to 15 nearly. He 

 considers the irregularity in the motion of the perigee, and of the equation 

 of the centre, as depending on a new expression which he has introduced, 

 involving the longitudes of the Earth and of Venus, the period of which 

 is 240 years. See FhiL Trans. 1828, Part i. Mr Bailey's Appendix, p. 

 269-271. 



2. Professor Sti^uve's new observations on Saturn's Ring. — In No xi. 

 p. 174 of this Journal, we have published the admirable observations of 

 Professor Struve of Dorpat, on Saturn and Jupiter. We are now enabled to 

 lay before our readers his new results, deduced from a much greater num- 

 ber of observations. Their accuracy may be inferred from the slight dif- 

 ference between the old and the new results. 



Outer diameter of outer ring - - _ 40".095 



Inner - - - - - 35.289 



Outer inner - - - - 34.475 



Inner - - - - - 26 .668 



Equatorial diameter of Saturn - - . - 17.991 



From which measurements we obtain the 



* The proper quantity is 2". 90 ; but Mr Bessel makes it 2". 65 only because he 

 pr(^)Oses to take the constant of aberration 20^'. 25 instead of 20". 00, as assumed by 

 Delambre. 



