inches. Mean of four IV. Microscopes. Dec. 3L 29.948 76 16 15.6 9.92 i 27 57.8 +0.4 66 47 6.42 47 9.22 47 11.22 47 10.92 47 9.445 15.87 9.64 11 5.06 0.68 46 59.13 47 7U 29.99 83 8U 29.928 90 16.27 8.51 49 0.65 9U 29.742100 16.36 8.11 42 32.15 10L 29.70 84.3 16.49 8.83 36 30.5 12L 29.606 90.5 16.73 8.54 25 47.9 13U 29.577 99.5 16.84 7.66 14L 29.784 80.5 17.02 8.68 16.0 9.17 3 17.25 7.43 4.13 " 6.38 " 6.91 4.66 7.66 46 57.84 46 54.5 9.0 47 11.6 The mean of all the observations derived from the upper limb is 66° 32′ 15′′.98, from the lower limb 66° 32′ 18′′.215, the mean of the two is 66° 32′ 17′′.096, which gives for obliquity 23° 27′ 43".162; this is probably the most correct way to proceed. From these observations it appears that I observe the Sun's apparent diameter too great. In this Solstice the Polar Point had been previously applied to the Observations. The Solstice for December 1828, which was observed alternately direct and by reflection, has been already recorded, page 11, amongst the Observations for the Latitude. Observations of Planets. 1. Inferior Conjunctions of Venus. Observations of the inferior Conjunction of Venus, December 1826, with the Mural Circle. The following South Polar Distances of Venus observed with the mural circle are neither corrected for refraction nor parallax. In the Observations after conjunction, the interval between the transits is to be deducted from the sun's culmination on the next following day, in order to have the transit of Venus on the given day. From December 18, till the 28th, the weather was unfavourable. On December the 14th, 15th, 16th, 17th and 18th, I had repetitions on Venus about the meridian, with Reichenbach's Circle, of which the abstract is subjoined. The above Zenith Distances are corrected for Refraction, but not for Parallax. The Reduction to the Meridian will serve to correct the Parallax. The culminations of Venus observed with the transit, have been corrected for semi-diameter, and the hour angle thence deduced is corrected for the acceleration of Venus above the fixed stars, which is here additive. It depends upon the relative situation of the Sun and Venus, whether in the repetitions left and right the planet can always be observed on the same side of the wire, or whether it must be observed alternately on different sides. The mean arc will be accordingly the zenith distance of the centre, or that of one of the limbs. Inferior Conjunction of Venus, July and August 1828, observed with the Mural Circle and Transit at Paramatta. The lower limb of Venus has been observed throughout. The observed Right Ascensions are those of the first limb before the conjunction, but after conjunction those of the last limb of Venus. The Sun's Parallax has been subtracted from his Refraction, but to Venus no Parallax has been applied. |