AT THE OBSERVATORY AT PARAMATTA. 69 



1828. 



Nov. 28.— At l"" 4™ 18» the Comet followed a Star (y) in 1'.8, being 30' 10" North thereof. 



r JR 21*^ 10"^ 22^ 5 

 The place of this Star according to //j«<. CeZ. is < p. ■ -.q ci/ qwI 



At l** 16" the Comet preceded a star (z) 42', and another star (a) 56' ; and was South of 

 a, 22' 15". 



Dec. 5. — At 1'" 1"> 0' the Comet followed a Star (/3) in 1" 2', and was 5' 26" North thereof. 



At !'■ 31"° 42% the Comet preceded 14 Delphini 28M2, and was 13' 50" South thereof. 



Fixed Stars. 



Determination of the Right Ascensions of some of the principal Stars of the 

 Southern Hemisphere, hy absolute, and equal Altitudes, 



1 . Absolute Altitudes. 



The weakness of the axis of the transit in Paramatta rendered it impossible 

 for its optical axis to move in one and the same plane in passing from the 

 north to the south of the zenith ; so that I could not place implicit confidence 

 in the right ascensions of the southern stars deduced from the northern by 

 means of this instrument. I was therefore desirous to establish the right 

 ascensions of some of the principal southern circumpolar stars, independently 

 of the transit, by methods not subject to any constant error, and I resorted first 

 to repetitions with Reichenbach's circle for observing the hour angles of these 

 stars when near their greatest azimuth circle, corresponding to times of the 

 sidereal clock, whereof the error was ascertained on the same days from equal 

 altitudes of the Sun, Sirius, and other known stars. Not to lose the time de- 

 voted at night to the transit and mural circle, I made these observations in the 

 day-time, having constructed for that purpose a table of azimuths and altitudes 

 for the star from 5 to 5 minutes, which enabled me to find the star at any time 

 for the left observation ; and as the table contained also the double zenith 

 distances, I had but to advance the nonius of the small circle by that quantity, 

 in order to have the star again in the field after half a revolution in azimuth. 

 Thus I could continue the repetitions to any extent with greater ease and 

 accuracy in the day-time than at night. The observations were made as much 

 as circumstances would admit east as well as west of the meridian, in order 

 to let the errors of the instrument compensate each other. The observations 

 were chiefly made at the time when the star's azimuth was a maximum, and 



