Position and Magnitude of the Rings of Saturn, according to Bessel and Struve, for every fortieth day in the year. p. Angle between the semi-conjugate axis of the ring ellipse, with the circle of declination; positive when east, negative when west. 1. Angle of elevation of the earth, above the plane of the ring, as seen from Saturn, positive when north, negative when south. a. Semitransverse axis of the ring ellipse. b. Semiconjugate axis; positive, when the northern surface of the rings is visible; negative, when the southern. It has lately been ascertained, that the planet is not exactly in the centre of the rings. The planet Mercury will be visible in the evening until the 11th of February, then in the morning to the 22d of April, then in the evening to the 15th of June, then in the morning to the 4th of August, then in the evening to the 12th of October, then in the morning to the 3d of December, then in the evening. It is with difficulty that this planet can be seen in any other position, except when at or near its greatest elongation from the Sun, which this year happen January 27th (elongation 18° 24'), March 10th (27° 30′), May 21st (22° 32'), July 8th (26° 29′), Sept. 17th (26° 29′), and Oct. 28th (18° 37'); but the following periods will be most favorable for observing it, this year, as during them it will not only be at its greatest distance from the Sun, but will be nearer the elevated pole, and consequently will remain longer above the horizon. From Jan. 16th to Feb. 4th, in the evening after sunset, bearing W. 15° S. "May 1st to June 4th, in the morning before sunrise, E. 23 N. Oct. 19th to Nov. 7th, 26 E. 6 S. The planet Venus will be visible in the evening to the 7th of March, then in the morning to the 20th of December, then in the evening; its greatest western elongation (45° 59') will take place on the 16th of May; but it will be the brightest, as evening star, on the 13th of January, and as morning star, on the 25th of April. The planet Mars will be visible in the morning to the 19th of September, then in the evening to the end of the year. The planet Vesta will be visible in the morning to the 8th of October, then in the evening. The planet Pallas will be visible in the morning to the 27th of April, then in the evening. The planet Juno will be visible in the morning to August 25th, then in the evening. The planet Ceres will be visible in the morning till the 30th of April, then in the evening. The planet Jupiter will be visible in the morning till July 5th, then in the evening. The planet Saturn will be visible in the morning till the 3d of February, then in the evening to the 14th of August, then in the morning to the end of the year. The planet Uranus or Herschel will be visible in the evening till the 26th of January, then in the morning to August 1st, then in the evening to the end of the year. The superior planets, or all but Mercury and Venus, will appear brightest when nearest to the earth, that is, when in opposition to the Sun. HEIGHT OF THE GREATEST OR SPRING TIDES IN 1830. Computed by the formula of La Place (Mécanique Céleste, vol. II. p. 289.) The unit of altitude, is the altitude of the tide which happens about a day and a half after the time of new or full moon; at the moment of new or full moon the sun and moon being at their mean distance from the earth, and in the plane of the equator. The unit of altitude of any place, multiplied by the numbers in the preceding Table, will give the height of the tide at that place. The unit of altitude at BOSTON, Salem, Marblehead, and Cape Ann, is 114 feet. At NEW YORK, St. Augustine, Block Island, Elizabeth Town Point, Florida Keys, Hillsborough Inlet, Nantucket Shoal and Town, New Bedford, Rhode Island, and Sandy Hook, 5 feet. At CHARLESTON, S. C., Monomoy Point, Port Hood, Prince Edward's Islands, St. Simon's Bar, and St. Simon's Sound, 6 feet. These, multiplied by the numbers in the preceding table, give the following, as the heights of the greatest tides, this year, in those places. It appears by the preceding Table, that the tides of February 23d, March 25th, October 3d, and November 1st, will be the greatest of all in 1830, but the positions of the sun and Moon will not be so favorable this year as the last, for producing a great elevation of the sea; the height of the tides, however, depends so much on the strength and direction of the wind, that it not unfrequently happens that a tide, which would, independently of this, have been small, is higher than one in other respects much greater. The following Table contains the unit of altitude of several ports and places on our coast, from the best authorities. The height of the enormous tides in the Bay of Fundy was ascertained from actual observation by a gentleman of Boston, in the summers of 1828 and 1829. feet. Advocate Harbour (Bay of Fundy) 50 Elizabeth Isles Andrews, St. Annapolis (Bay of Fundy) Augustine, St. Basin Bay of Mines (Bay of Fundy) Bay, 25 feet. 9 32 35 Gay Head 5 George's River 60 8 肆 Blomidom (Bay of Fundy) 55 Marblehead 66 Chat 66 Cod. "Sable "Split (Bay of Fundy) CHARLESTON (S. C.). Cumberland (Basin Fort), head } of the Bay of Fundy Digby (Bay of Fundy) Eastport 13 Mary's, St., Bar 63 Monomoy Point 4 14 9 12 16 28 8 8 5 30 7 9 9 51 12 11 7 6 Moose River (Bay of Fundy) 35 66 Island Mount Desert Mouths of the Mississippi Nassau (N. P.) 49 New Bedford 25 12 Partridge Island (Bay of Fundy) 55 Passamaquoddy River 25 The following Table contains the difference between the time of high water at Boston, and at a large number of places on the American coast, by which the time at any of them may be easily ascertained, by subtracting the difference at the place in question from the time at Boston, when the sign is prefixed to it, and by adding it, when the sign is +. The time of high water in the calendar pages, is of that tide immediately preceding the southing of the moon. |