1826.] making a minute Survey of the Heavens, 127 



heavens most filled with stars, are quite sufficient. Besides this 

 difficulty, now removed in a zone of 30° of declination, there is 

 another, viz. the perfecting of the charts by the eye, which is so 

 laborious and requires so much time, that a single individual can 

 make but little progress in it. This may, however, be removed 

 by the co-operation of several ; and the active zeal now preva- 

 lent among astronomers allows us to indulge in the hope that 

 many will assist in promoting so great and useful an under- 

 taking. 



It is therefore the wish of the Academy of Sciences to unite 

 for this object the friends of astronomy; and to procure for 

 them every possible facility. It invites all astronomers to assist 

 in filling up the 24 sheets of a complete celestial atlas, for which 

 the foundation has already been laid ; viz. from — 15° to + 15° 

 of declination and the 24 hours of right ascension : laying down 

 at the same time the following rules to be observed in the 

 execution. 



1°. The net work, or scale, to consist of squares for the de- 

 grees of decUnation and right ascension : each degree mea- 

 suring 5| Parisian lines (or 0-51 English inch). It should 

 extend from 4 minutes of time before the beginning of an hour, 

 to 4 minutes of time after its termination: and thus contain 610 

 squares. 



2°. In this net work are to be marked the stars observed at 

 Palermo, Paris, and Konigsberg, reduced to the beginning of 

 the year 1800.=^ 



3°. The largest of them should be marked after the manner 

 of the pattern sheet attached to the present plan : those stars 

 which are visible only through a telescope, by larger and smaller 

 black rings ; and those visible by the naked eye, by the addition 

 of rays.f 



4°. If a star has been observed but once, the same should be 

 marked by a short faint line projecting from one side of it; if 

 twice, or more frequently, by two such lines, one on each side 

 of it.j For stars visible to the naked eye, this kind of desig- 

 nation would lead to indistinctness, and is in fact needless, 

 since they are all described in Piazzi's catalogue ; and therefore 

 show, by their rays, that they have already been observed. 



5°. The sheets in this state must be compared with the 

 heavens : and all the stars, within the limits proposed for the 

 intended sheet, must be estimated by the eye, as correctly as 



♦ [The stars observed at Palermo are given in Piazzi's Catalogue : those observed at 

 Paris are given in the Histoire Celeste : and those observed at Konigsberg are given in 

 M. Bessel's Observations. — Sec] 



+ [These marks are similar to those adopted by 3Ir. Harding in his charts. The 

 exact mode of delineating the different magnitudes may be seen in the pattern sheet.-^ 

 Sec] 



t [For specimens of this mode of distinguishing the different stars, isee the pattern 

 sheet, alluded to in the note in page 126, — fee] 



