406 Mr. Pond on the different methods of 
and some of these appear to me to possess advantages so de- 
cided, that I venture to submit them to the consideration of 
this Society ; at the same time, conscious that the subject 
cannot excite a very general interest, I shall endeavour to 
abstain as much as possible from every unnecessary detail, and 
confine myself to the explanation of the general principles of 
the method which I propose to recommend. 
According to the method hitherto invariably followed in 
this Observatory in constructing a catalogue of stars, either 
in declination or right ascension, some one star has been 
taken as a point of departure, and the positions of all the rest 
determined by direct comparison with this alone. The decli- 
nations were determined by direct measurement with <y 
Draconis ;* and a. Aquilae was chosen as the common term of 
comparison in right ascension. This mode of proceeding with 
the mural quadrant, though evidently capable of improvement, 
was not so very objectionable, as when applied to the obser- 
vations made with the transit instrument; as the observer 
must be supposed desirous of obtaining the greatest possible 
accuracy from a given number of observations. 
Indeed, in the latter case, the principle is so very objection* 
able, that I cannot now help expressing some surprize that it 
should have been employed for so great a length of time. 
In the first place, every result deduced from the observation 
of each star is affected with a double error ; that committed 
in the observation of a. Aquilag, and that in the observation 
• This will evidently appear to have been the case, if it be considered that the 
plumb line in the mural quadrant performed no other office than that of maintaining 
the instrument in a given position. 
