28.08 25.61 0 16 48.89 0 16 28.85 +7.37 0 16 36.22 Mar. 21 8 0 16 47.88 30 27.25 25.60 7.39 7.393 7.43 7.45 7.462 7.48 Super. and in- ẞ Hydri. Mean Right Ascensions. وو 35.47 34.68 32.83 24.93 دو 7.527 32.46 1 31 28.89 1 31 29.06 2 13 31 29.25 21 31 29.04 2 13 31 28.11 31 31 28.05 5 1 31 28.57 7 1 31 29.79 91 31 29.81 9 13 31 29.55 10 1 31 29.06 15.705 2.205 15.84 2.215 14.81 2.219 14.83 2.233 2.247 16.317 15.45 12 1 31 28.76 16.14 2.246 18.386 12 13 31 28.66 16.65 +2.246 34.82 Mean Right Ascension, Jan.1, 1828, « Eridanil 31 17.484 26.22 7.445 33.66 8 12 16 45.21 10 12 16 45.85 11 0 16 43.73 12 0 16 42.6 13 0 16 43.67 13 12 16 42.02 14 0 16 41.85 16 12 16 40.68 18 12 16 41.54 19 0 16 39.69 29 0 16 39.86 31 12 16 40.29 31 0 16 41.11 Apr. 1 12 16 40.16 1 0 16 42.12 2 12 16 40.71 2 0 16 39.44 3 12 16 40.41 30 16 41.64 4 0 16 41.22 5 0 16 40.3 9 0 16 41.92 10 12 16 41.44 10 0 16 41.59 11 0 16 41.10 12 0 16 39.02 33.87 Before the conjunction the superior culminations take place immediately after noon of the given, but after conjunction immediately before noon of the next following day; but in the above Table they have been reduced to, and placed opposite to the days nearest the noon whereon they had been observed. I remark again that my object in observing equal altitudes was to have a check upon the transit, by a method independent of the errors arising from imperfections of the latter instrument, which were the more dangerous as, inclining all towards the same side, their apparent consistency made it difficult to discover their cause, and to subject them to mathematical laws, which we shall endeavour to do hereafter. Although observations of equal altitudes will deviate more on each side of their mean, this mean may be nearer the truth than that of the transit observations: it must be recollected at the same time that ẞ Hydri is within 12° of the Pole, and all the other stars are circumpolar 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 thus the right ascensions of the following stars have been established. 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 assistance 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 observation separately, and their mean has been applied to the mean of the microscopes 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 observations 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. inches. Therm. Microscopes. Refr. Red. 1827. Barom. inches. Therm. Microscopes. Refr. Red. June 23 29.85 47 0 57 22.7 57 26.7 57 45.2 57 33.0 1 25.22 14.13 June 24 30.00 46 389 35 19.5 35 23 35 27 35 32.2 í 29.66 14.22 inches. 36 56 7 56 10.7 56 8.2 1 27.5 31.65 Refract. and Reduct. 56 11.2 1 27.3 31.65 June 19 30.34 19.5 359 33 25 33 27.5 33 28.3 33 30 í 30.1 31.65 1 59.1 1 59.0 1 59.1 54 06.954 12.3 54 10.6 ☛ Octantis. (Ann. Var. — 5".739.) The South Polar Star. Superior Culmination. Refr. Bed III. IV. inches. '1 24.1 í 21.23 11.94 Aug.28 50.5 359 31 22 30 30.02 38 359 31 23 Sept. 13 29.83 41.4 359 31 18.8 32.5 31 28.5 31 34.0 31 32.6 1 30.23 11.73 1 42.0 1 42.0 1 42.0 31 33.4 31 32.3 1 31.39 11 31 36.331 30.0 1 3021 11.5 inches. Therm. Inferior Culmination. Microscopes. Reft. B I. II. IV. linches. June 9 29.95 58 2 16 40.8 16 42 16 49.2 16 48.9 í 20.29 2.72 June 8 29.89 53 359 7 33 7 34.7 7 38.5 | † 4120 1 31325 10 30.03 35 99 43 99 " 40.2 44.5 44.2 55.0 99 99 36.3 16 46.1 16 53.1 41.0 16 52 16 55.5 48.7 16 50.0 16 55.3 50.0 16 53.7 17 0.5 51.5 17 1.0 17 4.1 ,, 24.29 2.69 99 25.25 2.61 22.46 2.64 25.05 2.62 23.37 2.61 16 56.2 1 23.45 2.65 1 20.8 49 55.0 1 23.65 33.397 1 57.05 1 57.1 1 57.0 47 55.75 48 0.5 47 58.0 38 33.8 38 37.7 38 33.2 34 41.0 34 41.4 34 42.4 14 29.97 63 24.1 33.4 99 99 37.7 99 99 17 30.03 54 23.8 26.0 27.0 30.2 99 99 35.2 29.61 33.80 ,, 31.45 33.80 June 5.5... Mean... 358 39 25.6 39 31.7 39 35.6 39 31.11 31.29 33.405 Refract. and Reduct. Mean S. P. D. of r Octantis, Jan. 1, 1828 358 38 27.7 38 33.8 38 37.7 38 33.2 1° 34′ 41′′.82 by 31 Observ. -57.9 57.9 57.9 57.9 M 2 |