80 



MR. RUMKER'S OBSERVATIONS 



truth than that of the transit observations : it must be recollected at the same 

 time that /3 Hydri is within 12° of the Pole, and all the other stars are circum- 

 polar with the exception of Canopus. 



Besides the times of the equinoxes, equal altitudes of various stars were 

 observed during their conjunction and opposition with the sun, and thxis the 

 right ascensions of the following stars have been established. 



Stars. 



(3 Hydri 

 a. Eridani 

 Canopus 



^ Argus 



^ Crucis 



2 a Centau. 



Mean JR. begin- 

 ning of 1828. 



4 



22 



95 



137 



189 



217 



30.6 



26.13 

 1.9 



59.36 

 1.3 

 2.8 



Annual 

 Variat. 



39.09 



33.428 



19.81 



10.908 



51.296 



66.856 



Number of Observations *. 



27 Set of equal Altitudes 



31 



22 ■ 



13 



30 



20 



Each set of equal altitudes comprehends from 20 to 50 observations on each 

 side of the meridian. A set of absolute altitudes has been counted for half a 

 set of equal altitudes. 



The above stars in their upper and lower culminations, form in different 

 parts of the meridian so many meridian marks established without the assist- 

 ance of the transit : thus it is not likely that the optical axis of this instrument 

 could pass on the same day at the precise time through each of them, unless 

 the plane in which it moves be that of the meridian. 



South Polar Distances of Circumpolar Stars deduced from their Superior 

 and Inferior Culminations observed at Paramatta. 



The refractions and reductions for aberration, nutation and precession to 

 the mean places in the beginning of 1828, have been computed for each ob- 

 servation separately, and their mean has been applied to the mean of the mi- 

 croscopes for upper and lower culminations. The half difference between the 

 two thus corrected, gives the mean south polar distance for January 1, 1828. 

 The half sum is the polar point, which will serve hereafter for the reduction 

 of the remainder of the stars. 



* In determinations of positions of stars or of geographical places, the number and quality of ob- 

 servations upon which they are founded should always be stated, in order that their due weight may 

 be attached to them in comparisons with succeeding observations. 



