Mr. Pond's Catalogue, ^c, 281 



Aquilae., and some other stars. But from this time forward, I 

 propose to use the instrument in one position of the telescope, 

 with the hope of ascertaining, if not the parallax of these 

 stars, at least the limits, which it does not exceed. 



Though the change of position in the telescope, by which 

 all error of division is avoided, is one of the most beautiful 

 properties of this instrument, yet so accurately is it divided, 

 that I cannot perceive, with certainty, any effect produced by 

 this change, for I have often found as great a discordance 

 between two series of observations made on the same divi- 

 sions, as when they are entirely changed by a new position 

 of the telescope. What the error of division may amount to 

 in any one position, I cannot exactly say ; but, I think, when 

 the six microscopes are used, it can never exceed half a 

 second, and very rarely amounts to half that quantity. 



That some opinion may be formed of the accuracy of this 

 instrument, I have subjoined to the Catalogue the results of 

 the observations of some of the standard stars, whose places 

 I am anxious to determine with the greatest precision, since 

 I propose in future to determine all north polar distances by 

 comparison with these stars ; precisely in the same manner 

 as right ascensions are now determined by comparison with 

 the thirty-six stars, whose places have been so accurately 

 determined by Dr, Maskelyne. 



