208 GERARDI REGNERI POCKENS 



« that pass very near il , Ihough it faiied with regard lo parallax , haa been prodiicHvfl 

 « of Ihe most noble discoveries of anolher naturc. Al Ihe same timc it has given us a 

 « rauch jusler idea of Ihe immense distance of Ihe slars , and furnished us wilh an ap- 

 « proximation lo Ihe knowledge of thcir parallax that is much nearer the trulh Ihan we 

 « ever had before. Dr. Bradley, in a lelter to Dr. Ha Hey on Ihe suhjcct of a new 

 (( discovered motion of the fixed stars, says: « I believe I may venture to say , that ia 

 V (! eilher of llie Iwo stars last mentioned (y Draconis and ;; Ursae majoris) it (the 

 « « annual parallax) does not amount to 2". I am of opinion , that if it were 1", I 

 « « should have perceivcd it in the great number of observatious that I made, expecially 

 « « upon y Draconis; whieh agreeing with the hypothesis (without allowing any thiag 

 «( (( for parallax ) nearly as well when Ihe sun was in conjunction with , as in opposi- 

 « « tion lo , this star , it seems very probable , that the parallax of it is not so great as 

 « « one Single second. " As I do not know that any thing more decisive has been done 

 « upon the subject, it will not be amiss to see how far this method of finding the pa-! 

 « rallax has really been successful. The instrument that was used upon this occasioa 

 « was the same as the present zenilh sectors , which can hardly be allowed sufficient to 

 « shew an angle of one or even Iwo seconds wilh accuracy; yet on account of the great 

 « number of observalions , and above all Ihe great sagacity of Ihe observer, we will 

 n admit that if the parallax had amounled lo two seconds he would have perceived it, 

 « The Star on which these observalions were made is marked of the Ihird magnitude in 

 « the Calalogue of Ptolemy; in Tycho ßrahe's of the Ihird; in the Prince of 

 « Hesse's of the third ; in He velius's belween the Ihird and second; in Flamstead'a 

 « of ihe second ; and now appears a very bright star of the third , or small star of the 

 « second magnitude; Iherefore ils parallax is probably considerably less Ihan that of a 

 « star of the first magnitude. Several authors who have touched upon this subject seem 

 « to have overlooked this dislinction ; and from Dr. Bradley's account of the parallax 

 « ofy Draconis, have concluded the parallax of the slars in general not to exceed 1"; 

 « but this appears lo me by no means lo follow from the doclor's observalions. Il is 

 « rather evident that, for aught we know to the contrary, the stars of the first magni- 

 « lüde may still have a parallax of several seconds ; and I believe this to be as aecurate 

 « a tesult as that method is capable of giving , al leasl in latiludes where Ihere is not a 

 « Star of »he first magnitude that passes directly through the zenilh. [JVoie. De la Lan- 

 « de, in bis c^cellenl book of Asfronomy , says, that the prrallax.of the fixed stars has 

 « been proved lo be aisolulely insensible , art 2782. He reports the observalions of 

 <( Tycho Brahe, Picard, Hook, and Flamstead, and concludes, art. 2778, 

 « from the discovery of the aberralion by Dr. Bradley, (which it seems he also allows 

 « to be the most decisive upon the subject) that now the question about parallax i» 



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