Astronomical Society, 65 



5 observations of this star, and Piazzi has 46. It is scarcely possi- 

 ble that Bradley should be in error one second of time : and still 

 less probable that the mean of 46 observations by Piazzi should be 

 erroneous to such an amount. The result of Bradley's observations 

 (after allowing for the effect of precession) differs 8",5 in space 

 from those made by Piazzi : which quantity, divided by 45 (or the 

 interval of years between the two observers), will make the annual 

 proper motion of the star, if it really have any, about 0",19 in 

 space. But, this is not confirmed by the recent observations of 

 Mr. Pond j and we must look elsewhere for a solution of the diffi- 

 culty. That the position of a star of the third magnitude should 

 be so undecided at the present day that its Ai cannot be satisfac- 

 torily depended on, to a second of time, does not speak much in 

 favour of modern astronomy ; and shows us that a great deal still 

 remains to be done towards establishing the fundamental parts of 

 the science. * * * Amongst other suggestions I have imagined that it 

 might arise from a typographical error; and, in fact, if we sup- 

 pose a misprint of 10'' in the /R of y Cassiopece in Piazzi's Cata- 

 logue, that is, if we read iR=ll° 11' 17",6 instead of 11° 11' 7",6, 

 the whole difficulty will vanish, and the results of the observations 

 of Bradley, Piazzi, and Pond, will agree to the greatest exactness. 

 But, we are scarcely warranted in making such an alteration with- 

 out a reference to the original observations. Some suspicion how- 

 ever is excited that the printing is not strictly correct, from the 

 circumstance that Piazzi considers the annual proper motion in 

 JR, as deduced from Bradley's observations, to be = ; which 

 would agree with the amended reading as here suggested : but 

 which does not accord at all with the present reading in the Cata- 

 logue, since the annual proper motion is, as I have already ob- 

 served, in such case = — 0',19. 



" Before I close these remarks, I would observe that there are also 

 differences in the JR. of three other principal stars (besides that of 

 |3 Scorpii, which is acknowledged to be an error in the Greenwich 

 Catalogue) to which I am desirous of calling the attention of the 

 Society j and for which I can, by no means, account. These are 

 £ Ursce Majoris and (5 Cephei (both stars of the third magnitude) 

 and c Draconis, a star of the fifth magnitude. The two last differ, 

 as in the case of y Cassiopece, above a second in time from the Ca- 

 talogue of Mr. Pond : but £ Ursce Majoris differs as much as 1*,4. 

 The case of this last star is the more remarkable, since the obser- 

 vations of Bradley and Piazzi correspond with wonderful exact- 

 ness ; there being a difference of only one second, in space, between 

 them, after a lapse of 45 years : whereas from the time of Piazzi to 

 the year 1825, a period of only 25 years, there appears, from Mr. 

 Pond's observations, to be a difference of upwards of 20". 



" The whole of the computations relative to the positions of 

 these stars, I have frequently repeated, and can assure the Society 

 that there is no error in the results as printed in their Catalogue. 

 Time only, and further observations, can clear up these apparent 

 difficulties." 



New Series. Vol. 3. No. 13. Jan. 1828. K A paper 



