35 



tend to point out a parallax in a. Lyroe, a, Aquilae, Arcturus, « 

 Cygni, and « Ophiuchi, and some others. M. Piazzi considers 

 c& Aquilas as having no discernible parallax, whereas my ob- 

 servations tend to point out that a Aquilae has a greater 

 parallax than any other star that I have observed. Besides 

 this discordance between the results of my observations and 

 those of M. Piazzi, it is to be noticed that other results ob- 

 tained by instruments executed by the first artist, and by 

 observers justly celebrated, do not accord with mine in point- 

 ing out a parallax. Itis therefore with great diffidence that 

 I offer my results to the Academy. These results tend to 

 prove that the parallax (the angle subtended at the star by 

 the diameter of the earth's orbit) of a Ljtsb, by 152 ob- 

 servations amounts to 2" ; of » Aquil<E, by 96 observations 

 = 5", 5 ; of Arcturus, by 92 observations = 2", 2 ; of « Cyg- 



as would result from a double parallax of 20" whereas by my observations I find no 

 indication of parallax in this star. Indeed from tlie account given in the Con. des 

 Temps, by M. Delambre, the results of M. Piazzi, as to parallax, cannot be consi- 

 dered as entitled to much confidence, and in consequence M. Delambre may appear 

 justified in making the following remark. 



" Malgre les efforts dont nous venons rendre corapte, il ne parait pas que nous 

 " ayons encore rien de bien certain sur la distance des etoiles. Cette connaisance est 

 « peut etre du norabre de celles qui nous seront toujours refusees." 



No one should consider this as reflecting any censure on the observations of a person 

 who has rendered such excellent services to astronomy. It should only be understood 

 that the instrument used by M. Piazzi was inadequate to the research. 



