46 Statement of a Plan for 



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

 has addressed a Letter to Mr. Herschel, which more fully 

 and clearly developes the views of the Academy. 



Translations of the Prospectus and of the Letter, above al- 

 luded to, are subjoined. And the Council of the Astronomi- 

 cal Society trust that, in thus giving publicity 1o the Plan pro- 

 posed, and circulating it amongst the members, it will be 

 needless to add any arguments in favour of a proposal, which 

 promises, much more fairly than any other that has yet been 

 suggested, to accomplish so important a desideratum in mo- 

 dern astronomy. 



London, June 9, 1826. 



Prospectus, 



The modern celestial charts, by Flamsteed, Bode, and 

 Harding, 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. 

 Nevertheless, 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 increased 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 

 behind the perfection attainable even in his time: and it was 

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

 vented this great astronomer and his successors from attempt- 

 ing 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 un- 

 noticed, which, although of equal brilliancy, had not yet been 

 considered. 



Nevertheless, it is desirable that we should possess charts 

 that may be perfect to a certain limit ; and the more desirable 

 the further this limit be removed. If we determine that limit 

 by the smallest stars yet visible through one of Fraunhofer's 

 comet- seekers of 34 lines aperture and a magnifying power of 

 10 times, (and which can be observed without difficulty by 

 Reichenbach and ErtePs meridian circles, provided with 



Fraunhofer's 



