2. TRANSIT OF MERCURY, MAY 8TH, 1845. "THE first and second contacts of the planet with the sun's limb were lost by clouds. 66 Mercury was first seen on the disk of the sun at 2h 48m. 31" sidereal time. Observations for the relative positions of the planet and the sun were immediately commenced, and were continued throughout the transit, though frequently interrupted by the passage of cumulus clouds, which prevailed through the day.. "The tremulous state of the atmosphere towards the close of the observations was unfavorable to the accuracy of the measurements. "It was thought, at one time, that a luminous spot was visible near the centre of the disk of the planet; any decisive evidence of its existence was precluded by the limited power of the instrument. "At the last contact, the singular phenomenon of the inosculation of the adjacent edges of the planet and sun was distinctly noticed by both observers. The present instance is one of much interest, as it has hitherto been supposed that Mercury is not thus affected when in close proximity to the sun's limb, although this sort of phenomenon has frequently been noticed in the transits of Venus (see Mem. Royal Ast. Soc., Vol. X.). "The third and fourth contacts were pretty well observed, but owing to the oblique and slow motion of the planet across the sun, combined with the unsettled state of the atmosphere, we were unable to note the times of contact with sufficient accuracy to be of much value for the purposes of terrestrial longitude. The times noted were as follows: "In the following observations, B' denotes W. C. Bond. “Micrometric Measurements of the Differences of Right Ascension of Mercury and the Sun's Limb, corrected for Refraction, and also for the Sun's Motion in the Intervals of Transit. The telescope used was a Refractor of 24-inch aperture and 46 inches focus, furnished with Troughton's spider-line micrometer. * The original record was 22.0 s., but partially altered to this effect. + Apparently in error 2 s. for 40.6. 7.3-1.2 73.8 1.0 0.6-0.4" 3.80.1 81.8 8.0 0.6+0.2 85.6 3.8 3.8 0.0" 66 0.7 -0.6 86.3 0.7 5.40.2 87.7 1.4 7.3-0.7" B2 0.6-0.1 0.7-0.7" 1.0-0.8 92.7 5.0 5.4+0.4" 2.52.2 94.2 1.5 1.0-0.5". "Micrometric Measurements for Differences of Declination of Mer cury and the Sun's North and South Limbs. Corrected for Re +11++1+1+1++11+1+++ + 9.6 9.9 + 6.0 +2.7 + 1.0 3. OBSERVATIONS ON THE COMETS OF 1845 AND 1846. Observations on the Comet of June, 1845, made at the Cambridge Observatory. Lat. 42° 22′ 49′′. Long. 4h 44m. 32". The observed differences of A. R. and Dec. were applied to the A. R. and Dec. of the stars referred to the mean equinox of January 1st, 1846. 1845. d. h. m. 8. h. m. S. Star of Comparison. A. R. No. of June 2 15 39 063 27 32.7 38 15 27 3 24 59.57 38 03 37.0 4 66 13 09 24 52 6 3 34 41.0242 05 01.4 19 9 22 197 59 56.0 35 52 39 8 00 05.2335 54 56.0 Comet-star. Comet-star. 30 30 8 37 18 50 29 19 19.6 46422-2223 CO 1 3 24 09 02 57 14.6+06 04.28 29 2 B A. Cat. 8 37 45.90 28 43 34.3 8 43 21.03 23 55 06.2 2 B. A. Cat. 66 "The comet was first seen at 14h 15m., June 2d. The observations of this morning are made with the spider-line micrometer, and under favorable circumstances. "June 4th. The differences of A. R. were obtained this day from the hour-circle of the equatorial, which reads to single seconds of time. The comet could be seen with the naked eye after most of the stars of the second magnitude had disappeared. It being somewhat cloudy, the length of the tail could not be well determined. The nebulosity was very much condensed and beautifully defined near the head of the comet, the tail was plainly divided into two branches. " June 6th, A. M. The head of the comet broad and full; in the course of six hours, it has undergone a remarkable change, becoming pointed, and appearing with a spur or secondary tail (which is the brightest of the two) of two degrees in length. The axes of the tails are inclined at an angle of twenty degrees, though the estimation is quite uncertain. The principal tail may be traced through five degrees. The observations are made as on the 4th. "On the 9th and 10th, the observations are made with the spider-line and annular micrometers. The changes in the physical appearance of this comet from night to night are particularly interesting. “June 25th. Observed with the spider-line and annular micrometers, the comet being still sufficiently bright to bear illumination; its tail is one or two degrees long. Observations on the Comets of February and May, 1846. Cambridge Mean Solar Time. 1846. d. h. m. 8. Feb.26 08 11 44 Mar. 1 07 35 35 66 2 07 30 06 3 07 17 51 66 21 07 30 16 0 46 57.433 45 28 0 48 45.67 34 01 38.1 16 08 20 08 0 07 32.054 58 59 "27 15 30 35 23 38 11.062 47 0 04 55.59 55 00 08.1 10 66 23 42 55.73 62 53 14.8 2 "[4149. 0 57 45.04 3 22 26.1 2 Bessel's Zone, 36. Bessel's Zone, 331. Hist Cel., p. 307. Bessel's Zone, 390. Hist. Cel., p. 20. Bessel's Zone, 443. May 4 15 02 17 23 09 51.167 21 12 23 12 19 32 67 16 10.8 18 10 48 1621 20 44.574 35 44 21 10 17.07 74 36 46 9 19 11 07 23 21 08 56.374 54 2321 04 30.00/74 54 50.0 12 09 02 48 6 57 49.3 33 58 13 6 58 06.6334 04 00.3 " p. 212 (c 22 09 01 38 6 47 44.5 47 43 00 June 3 09 31 20 7 01 27.8 38 11 46 |