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Astronomical Observations Made at Hudson Observatory, Latitude 41° 14' 42".6, North, and Longitude 5H

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Astronomical Observations Made at Hudson Observatory, Latitude 41° 14' 42 ' ' ' . I * < ' . ■ ' „ TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY. ARTICLE I. Astronomical Observations made at Hudson Observatory, Latitude 41° 14' 42".6, north, and Longitude 5h. 25m. 395.5, west. Third Series. By Elias Loomis, Professor of Mathematics and Natural Philosophy in the University of the City of New York. Read November 15, 1844. The general plan of observation has remained unchanged since the foundation of the observatory. The clock has not been stopped since January 31, 1840; but from the effects of dust and moisture, operating upon the pendulum and wheels, its rate has been somewhat affected, as will be seen from pages four to seven. The third spider line of the transit broke, April 20, 1841, and its place was supplied by the moveable micrometer line for a few days, until it could be replaced. July 14th, the fourth line broke, and the micrometer was substituted in its place. November 16th the micrometer broke; and December 28th, the second line also broke, leaving only three vertical lines. April 21, 1842, I undertook to replace all the lines, and, after some ineffectual attempts, succeeded in introducing fibres of silk from the cocoon. The lines, seven in number, w^ere secured in their places by bees-wax, melted by a warm iron. These lines are a little coarser than the spider lines, are not quite so smooth, and are not perfectly straight. Nevertheless, by always observing transits on the same part of the lines, this last evil is mostly obviated. The equatorial intervals deduced from the transits of one hundred stars observed at all the wires, have been determined as follows:— 18.033; 18.537; 18.595; 19.123; 17.047; 18.679. VOL. X.-1 ‘2 ASTRONOMICAL OBSERVATIONS The intervals are quite unequal, but the reduction of the mean of all the wires to the central wire is no greater than when the instrument was first received, being Os.107 x secant of the declination; positive above the pole, and negative below. I have therefore not attempted to change the position of the lines, as with a proper method of reduction the inequality of the intervals does not affect the accuracy of the observations. The pendulum of the clock appears to be somewhat under-compensated,—its daily rate being about one-second slower in summer than in winter. I. LATITUDE OF HUDSON OBSERVATORY. During the summer of 1841, I observed twenty-four culminations of Polaris; in 1842, fifteen culminations of Polaris, and four of (3 Ursse Minoris; and in 1843, fifteen culmina¬ tions of Polaris. They were all made in the usual way, alternately direct and by reflexion from mercury. The errors of the microscopes were found to be as follows: North Polar Distance. A. B. c. Mean. 1841, June, 358° 25'—30' — 1".5 + 1".3 + 2".2 + 0".67 278 55—60 — 1 .9 +1.1 + 5 .0 + 1 .40 July, 1 30—35 — 1 .6 + 0 .2 + 3 .1 + 0 .56 275 55—60 — 1 .9 + 0 .3 + 6 .0 + 1 .47 1842, June, 358 25—30 — 0 .1 — 0 .4 + 1 .0 + 0 .20 278 55—60 — 2 .1 + 0 .5 + 3 .3 + 0 .58 July, 15 10—15 — 1 .7 + 0 .8 + 3 .3 + 0 .82 262 15—20 — 1 .9 + 1 .0 + 3 .3 + 0 .80 1843, June, 358 25—30 — 0 .5 — 0 .2 + 0 .7 + 0 .00 278 55—60 — 1 .6 + 0 .7 + 4 .1 + 1 .10 The places of the stars are taken from the Nautical Almanac, and require corrections. In the Almanac for 1843, the declination of Polaris is corrected + 0".50 to conform to the Greenwich observations, and in that for 1844, the correction is given + 0".38. Ac¬ cordingly, the declinations of the Almanac for 1841 and 1842 have been increased 0".38, and those for 1843 diminished 0".12. In the Almanac for 1842 the declination of (3 Ursse Minoris is corrected — 0".90, while the Almanac for 1844 gives the true correction — 0".46. The declination for 1842 has accordingly been increased 0".44. The following are the results of the observations: Date. Latitude. No. of Obs. Lower culmination of Polaris, 1841, May 14, 41° 14' 44". 1 12 15, 40 .7 9 19, 42 .6 9 20, 40 .8 9 21, 39 .7 9 27, 43 .7 9 28, 42 .2 9 29, 40 .3 9 31, 42 .9 6 June, 2, 40 .2 9 3, 42 .5 9 4, 43 .9 9 5, 43 .0 9 7, 43 .0 9 8, 41 .7 5 9, 40 .9 9 AT HUDSON OBSERVATORY. 3 Date. Latitude. No. ol' Obs. June 10, 41° 14' 43".5 9 11, 42 .3 8 14, 40 .9 9 16, 42 .5 9 Upper culmination of Polaris, July 20, 41 .5 6 21, 42 .5 7 22, 41 .8 9 23, 43 .3 9 Lower culmination of Polaris, 1842, May 12, 40 .1 13 13, 44 .0 9 14, 44 .5 9 16, 42 .4 8 24, 42 .4 7 27, 42 .0 7 30, 42 .4 7 31, 43 .1 9 June 1, 44 .3 7 4, 41 .0 8 6, 43 .0 8 11, 40 .9 10 13, 42 .7 10 15, 42 .7 8 17, 42 .7 5 Upper culmination of (3 Ursae Minoris, July 2, 43 .3 4 6, 41 .5 6 9, 44 .8 6 11, 44 .9 6 Lower culmination of Polaris, 1843, May 15, 44 .1 9 18, 44 .0 6 19, 43 .2 7 20, 43 .5 8 24, 44 .4 6 27, 44 .2 11 29, 44 .7 12 31, 40 .9 8 June 1, 40 .5 8 8, 42 .3 10 12, 42 .6 8 13, 42 .2 8 16, 43 .0 6 17, 43 .0 7 19, 42 .3 7 Mean of fifty-eight culminations,. 41 14 42 .7 The result here obtained accords very well with the observations of 1840. If we apply to that result the correction of the Nautical Almanac, 0".38, and take the mean of the observations of 1840, 1, 2, and 3, we have from sixty-three culminations of Polaris and four of Ursae Minoris the latitude 41° 14' 42" .6, which is my final result. II. OBSERVED TRANSITS OF THE MOON AND MOON CULMINATING STARS AT HUDSON OBSERVATORY. The following list is a continuation of that given on pages 143—145 of Second Series. The mode of reduction is explained on page 142. 4 ASTRONOMICAL OBSERVATIONS No. No. No. Date. Star. Wires Meridian Transit. Clock’s rate. No. Date. Star. Wires Meridian Transit. Clock’s rate. Obs. Obs. 1841. 1841. March 2 C.Tauri 5 5/t.43?n. 2s.50 — 2s.02 142 Moon 1 L. 4 15/i.34?«.10s.60 x Aurigae 5 6 4 57 .30 b Scorpii 5 15 41 18 .18 126 Moon 1 L. 5 6 50 16 .86 § Scorpii 5 15 50 49 .14 8 Geminorum 5 7 10 20 .12 June 30 8 Scorpii 5 15 50 47 .14 — 2 .00 a2 Geminorum 5 7 24 10 .24 143 Moon 1 L. 5 16 29 20 .98 March 3 8 Geminorum 5 7 10 18 .84 — 1 .75 25Scorpii 4 16 36 58 .64 a3 Geminorum 5 7 24 8 .02 144 July 3 Moon 2 L. 5 19 16 24 .26 — 1 .84 127 Moon 1 L. 5 7 55 57 .10 h3 Sagittarii 5 19 26 46 .42 x Cancri 5 8 10 45 .58 57Sagittarii 5 19 42 41 .52 9 Cancri 5 8 22 12 .68 July 26 a3 Librae 5 14 42 11 .36 — 2 .00 Mar. 29 l Tauri 5 5 28 9 .52 — 1 .69 145 Moon 1 L. 5 15 17 0 .30 128 Moon 1 L. 5 6 30 52 .92 7t Scorpii 5 15 49 21 .12 Mar. 30 1 Geminorum 5 6 54 40 .66 — 1 .07 July 28 a Scorpii 5 16 11 33 .94 — 2 .15 129 Moon 1 L. 5 7 35 0 .42 a Scorpii 5 16 19 41 .63 6 Cancri 5 7 53 45 .28 146 Moon 1 L. 5 17 7 33 .70 130 April 1 Moon 1 L. 5 9 32 42 .92 — 1 .23 9 Ophiuchi 5 17 12 17 .52 a Leonis 5 9 59 53 .24 3 Sagittarii 5 17 37 36 .16 April 2 o J^eonis 5 9 32 37 .20 — 1 .48 July 29 9 Ophiuchi 5 17 12 14 .88 — 2 .84 a Leonis 5 9 59 51 .48 3 Sagittarii 5 17 37 33 .12 131 Moon 1 L. 5 10 26 28 .92 147 Moon 1 L. 5 18 2 59 .38 x Leonis 5 10 56 46 .86 fi' Sagittarii 2 18 4 14 .95 April 3 48Leonis 5 10 26 26 .46 — 1 .58 x Sagittarii 5 18 18 9 .08 X Leonis 5 10 56 45 .28 Aug. 1 c Sagittarii 5 19 52 45 .94 — 2 .21 132 Moon 1 L. 5 11 18 4 .44 133 Capricorni 5 20 11 57 .68 Leonis 5 11 28 45 .00 148 Moon 1 L. 5 20 38 50 .04 /3 Virginis 5 11 42 21 .26 Moon 2 L.* 5 20 40 59 .06 April 27 a3 Geminorum 5 7 23 47 .88 — 1 .59 ft Aquarii 5 20 43 56 .96 f3 Geminorum 5 7 34 55 .96 v Aquarii 5 21 0 48 .26 133 Moon 1 L. 5 8 17 11 .92 Aug. 2 ft Aquarii 5 20 43 55 .48 — 1 .52 8 Cancri 5 8 35 0 .26 v Aquarii 5 21 0 46 .70 April 28 8 Cancri 5 8 34 58 .94 — 1 .32 149 Moon 2 L.
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