Q02 Mr. Pond's Catalogue of Eighty -four 



Remarks on the above Observations. 



oc Lyrae and x Aquilse having been supposed subject to a 

 sensible parallax, I have, as I mentioned before, reserved them 

 fo^ future examination. The observations which I have already 

 made on these stars, and particularly on cc Aquilae, are not 

 incompatible with this supposition, though I cannot at present 

 venture to decide whether the small discordances I have met 

 with are to be attributed to any regular cause, or are only 

 accidental. 



Whenever I speak of the degree of exactness to which any 



result may be depended upon, I allude only to the mechanical 



measure given by the instrument. I have every reason to 



believe, that if two fixed and well defined points could be 



placed in the plane of the meridian, I could, in a very short 



time, measure their angular distance to within a tenth of a 



second; but astronomers must be well aware that the stars 



are not presented to us in this simple form, and that the sources 



from which small errors may arise, either in the observations 



themselves or subsequent computation, are so very numerous, 



that anomalies will occur even to the most careful observer, 



which he will in vain endeavour to explain. With respect to 



the parallax of a Lyr^e, I might observe that it is a star so 



badly defined, and so little adapted for exact observation, that 



a parallax of half a second would not be easy to determine 



even with the Greenwich circle, 



u Aquilae is in some respects a better star for observation, 

 but only half its actual parallax would be sensible in decli- 

 nation. 



