IX. Comparison of the North Polar Distances of Thirty-eight 

 Principal Fixed Stars , on the 1st of January 1800, as de- 

 termined by Observations made at Greenwich, Armagh, 

 Palermo, Westbury, Dublin, and Blackheath. By 

 S. Groombridge, Esq. Blackheath, F. R. S. Lond. 

 Communicated by Dr Brewster. 



[Read 16th November 1812.] 



T3 Y comparing the longitudes and latitudes of the fixed stars 4 

 ■*-* as computed from their right ascensions, and north polar 

 distances, determined by observations made at distant periods, 

 Astronomers have been enabled to ascertain, with the utmost 

 accuracy, the precession of the equinoxes. The great accuracy, 

 however, which has lately been introduced into the construc- 

 tion of astronomical instruments, and the more general culti- 

 vation of Practical Astronomy, will hereafter be the means of 

 ascertaining the minute changes in the places of the fixed 

 stars, which have been denominated their proper motion, and 

 which, probably, arise from a motion of the solar system in 

 absolute space. 



The observations made at Greenwich during the last fifty 

 years, have been chiefly upon thirty-six of the principal fixed 

 stars. Observations were also made upon y Draconis, as being 



near 



