438 Astronomical and Nautical Collections. 



ii. Remarks on the Solar Tables, by Thomas Hen- 

 DEEsoN, JEsq, 



The discordances, which Mr. South has observed, between 

 the computed and the observed Right Ascensions of the Sun, 

 may be chiefly accounted for by the following considerations : 



De Lambre's Solar Tables, from which the computations 

 of the Nautical Almanac are made, were published in 1806, 

 but were constructed some years previously. He determined 

 the Epochs and mean motion by a comparison of Bradley's 

 Observations, about 1752, with Maskelyne's, about 1802, 

 reduced by the Catalogues of Stars then most approved. 

 Since the publication of these Tables, M. Burckhardt has 

 compared the Epochs with the Greenwich Observations, and 

 has reduced them by more correct catalogues, viz., Brad- 

 ley's Catalogue for 1756, computed by Maskelyne, and 

 Maskelyne's latest Catalogue for 1805. In this manner he 

 has found that the secular motion in De Lambre's Tables 

 should be increased by 12''.2, and that the Epoch for 1801 

 should be increased by 0".80. See his Memoir " Sur les 

 Masses des Planetes," in the Connaissance desTems for 1816, 

 p. 341. Consequently the Epoch for 1822 is too little by 

 3".3r=0\22 in time. But Mr. Pond's Catalogue, which 

 Mr. South has used in his computations, exceeds the above 

 Catalogues when reduced to 1822 by 0'.31 ; and therefore, 

 from these two causes, the Sun's observed Right Ascensions 

 ought to exceed those computed in the Nautical Almanac by 

 0'.53, which agrees very well with the quantity found by 

 Mr. South. 



Supposing the mean places and motions of the sun, moon, 

 and planets relative to the stars to be well determined, if 

 any change should afterwards be made upon the mean places 

 of the stars, or rather of the equinoctial point, or upon the 

 precession of the equinoxes, the same changes should be 

 made upon the mean places and motions of the sun, moon, 

 and planets, otherwise discordances must ensue. From what 

 has been said it would appear, that the source of the dis- 

 cordances found by Mr. South lies here, and not in the im- 

 perfectioDs of the Solar Tables. These discordances rather 



