1826.] making a minute Survey of the Heathens. 125 



stars (to the 9th and 10th magnitude) that have escaped the 

 observation of preceding astronomers. 



In order to prevent any confusion in the distribution of these 

 portions of the heavens, it has been thought proper that the 

 whole plan should be placed under the superintendence and di- 

 rection of the Royal Academy of Sciences at Berlin : and they 

 have accordingly issued a Prospectus, giving a detail of the 

 plan proposed. A copy of that Prospectus was forwarded to 

 the Astronomical Society : but some of the parts requiring ex- 

 planation, Mr. Herschel was requested to obtain further infor- 

 mation on those points which appeared to be ambiguous. In 

 reply thereto, M. Encke (the Secretary to the Academy) has 

 addressed a letter to Mr. Herschel, Vv^hich more fully and 

 clearly developes the views of the Academy. 



Translations of the prospectus and of the letter above alluded 

 to are subjoined. And the Council of the Astronomical Society 

 trust that, in thus giving publicity to the plan proposed, and 

 circulating it amongst the members, it will be needless to add 

 any arguments in favor of a proposal, which promises, much 

 more fairly than any other that has yet been suggested, to ac- 

 complish so important a desideratum in modern astronomy.] 



The modern celestial charts, by Flamsteed, Bode, and Har- 

 ding, contain only those fixed stars whose places at the time of 

 their publication were astronomically determined. The number 

 of these, however, has gradually increased from 3000, (marked 

 in Flamsteed's catalogue and the atlas founded on it,) to nearly 

 50,000 as given in the Histoire Celeste and in Piazzi's catalogue ; 

 the whole of which are marked in Harding's charts. Never- 

 theless, these celestial charts are very far from containing all the 

 stars visible by means of the telescope ; the number of which 

 seems to be immense, or to increase without limit with the in- 

 creased power of this instrument. Indeed we can never expect 

 to obtain charts that are absolutely perfect ; and if we aim at 

 any degree of accuracy, it can only refer to the assumed limit 

 of the magnitude or brightness of the stars. 



Before the discovery of telescopes such a limit was fixed by 

 the power of the eye, and the charts were capable of receiving 

 a certain degree of perfection founded upon it. Flamsteed, 

 however, although he added many new stars, remained far be- 

 hind the perfection attainable even in his time : and it was pro- 

 bably the immensity of the number of the stars which pre- 

 vented this great astronomer and his successors from attempting 

 to perfect their charts beyond a certain limit, and induced them 

 to remain contented with noticing only those stars that were 

 astronomically determined ; leaving many others unnoticed, 

 which, although of equal brilliancy, had not yet been con- 

 sidered. 



Nevertheless it is desirable that we should possess charts 



