Rcplij to RemaiJis an l/ie \iiuiical Aliiuniuc. 205 



of the Nautical Almanac has been printed ofF, and if the altera- 

 tion had been material, it would have been right to have noticed, 

 in that page, that it had not been applied to the computed 

 apparent places ; but the whole almanac appearing under the 

 authority of the Astronomer Royal, it could not be necessary 

 to state that the places of the stars were immediately deduced 

 from his catalogues, and from his observations. But it would 

 ])erhaps be as well hereafter to prefix the mean place for the 

 year to the apparent places. With respect to the remarks in 

 p. xix, the editor of the Nautical Almanac would think it unbe- 

 coming to interfere in any manner with a catalogue furnished 

 officially by the Astronomer Royal, upon the basis of his own 

 observations; and he would not hesitate to admit still greater 

 fluctuations from the mean determination of former years, if 

 they were supported by such authority. 



5. P. xxii. — " Table XI contains a list of all the eclipses of 

 Jupiter's satellites, marked as visible at Greenwich, deduced 

 from the Connaissance des Terns, for 1822, by deducting the 

 difference of the meridians, or 9' 21". The times of the eclipses 

 in that work have been computed from Delambre's new tables, 

 published in 1817. [Note. — The Commissioners of the Board 

 of Longitude have deferred the use of these tables till the year 

 1824, a period of seven years from the date of their publica- 

 tion. This is nearly fulfilling the injunction of Horace, nonum- 

 que prematar in annum. It certainly gives ample time for the 

 detection of any error.) I know not from what tables those in 

 the Nautical Almanac have been computed (the laudable custom 

 of informing the public on these points having been for some 

 years omitted,) but there is so striking a difference between the 

 results in the two works, that I thought it might be acceptable 

 to the practical astronomer to have them presented at one view. 

 The differences amount, in some cases, to 2' lo". If the com- 

 putations in the Nautical Almanac have been made, as formerly, 

 by two separate persons, and should prove incorrect, it is sin- 

 gular they should both have fallen into precisely the same 

 errors." 



In the Preface to the Nautical Ahnanac (ov 1823, it is ob- 

 served, that " the tables of the planetary motions, which have 

 been employed, are chiefly those which are printed in the third 

 volume of Professor Vince's Astronomy," and the eclipses of the 

 satellites are not included in the exceptions to this remark. 

 The fact is, that these tables were actually employed, with such 

 additions as were required for bringing them down from 1820 

 to 1823, and these were furnished, at the request of the Astro- 

 nomer Royal, by the late Mr. Crossley, and by a well known 

 German mathematician and geographer, conjointly. Mr. Bailey 

 may well think it singular that two separate persons should 

 agree in falling into the saine errors, and that these errors 



