130 Statement dfa Plan for [Aug. 



are intended as a guide to future astronomers, whereby they 

 may know, at one view, whether there exists a star that has 

 never yet been observed. In this point of view these new maps 

 cannot by any means render superfluous the Atlas already puo- 

 lished by M. Harding, which contains all the necessary details 

 to be able to distinguish exactly in what place of the heavens a 

 comet or a new star is seen. But the different objects of these 

 two maps require also a different arrangement. M. Harding has 

 taken his stars from the Histoire Celeste and from other cata- 

 logues, and in the regions where the observations were not 

 sufficiently numerous, he has made up the deficiency as well by 

 his own observations as by drawings. We wish that, in the new 

 maps, only those stars aheady observed should be noted, (viz. 

 witn one or two dashes,) which are found in books that are in 

 the hands of every astronomer ; and in order not to increase 

 liselessly their number, we propose to hmit those books to the 

 following ones ; 1^. The Catalogue of Bradley (Bessel Fund. 

 Ast.) 2°. Piazzi's Catalogue (Palermo 1814); 3°. The Histoire 

 Celeste of Lalande ; 4°. Bessel's Zones. If a star shall be 

 found in any two of these books we may be certain that it is a 

 fixed star ; if it is found in one only, it may be a planet or a 

 moving star. It is therefore necessary that every one who 

 wishes to take a part in this plan should also take upon himself 

 to reduce, to the same epoch, the observations of the Histoire 

 Cdeste and of M. Bessel's Zones, in order to be able to decide 

 whether a star is either the same, or has only been affected by a 

 very remarkable proper motion. Fortunately this reduction 

 will be found neither difficult nor long, by means of the Tables 

 of Reduction that M. Schumacher has caused to be computed 

 for the Histoire C<^leste,* and by the help of those Tables that 

 M. Bessel has adjoined to his Zones. I have no hesitation to 

 assert, by my own experience, that I should be able in eight 

 days to compute all the necessary reductions for a whole hour in 

 AR : and that at the utmost 15 days would be sufficient for 

 every case. 



M. Bessel's tables of reduction give the formula 



(1825) AR = ^ + A; 4- A:' (^- D) X -01 

 (1825) Decl. = ^ + d + d' {^- B) x -01 



For example, Bessel gives for the I35th zone, the first of the 

 ninth book, 



k k' d d' 



4h +0"288 ««|+0"Of.OI|-56"30 . ^q I3"68 y^.^fio 

 SO 0,225 °^1 +0,06211-61,03 ^''''13,73 "-^° 



whence, we have for the first five stars, 



* [Sammlung von HUlfiitafeln. Vol. u..mmSec»] 



