was 83° 30' 0" (Z. N.), the index correction-3′ 15′′, required the latitude. Ans., lat. 65° 0′ 22′′ N. (109.) May 3, 1853 in long. 14° 20′ W. the observed meridian altitude of sun's upper limb (in artificial horizon) was 30° 2' 30' (Z. S.), index correction 1′ 15′′, required Ans., lat. 59° 34′ 14′′ S. the latitude. (110) July 17, 1853, in long. 72° 30' E., the observed meridian altitude of sun's upper limb (in artificial horizon) was 52° 30' 0" (Z. N.), index correction+2' 10", required the latitude. Ans., lat. 85° 15′ 16′′ N. To find the latitude by the meridian altitude of the moon, and its declination, &c. Since the moon's declination, &c., are given in the Nautical Almanac, for Greenwich mean noon, we must get a Greenwich date in mean time. 1. Find a Greenwich date in mean time. 2. By means of the Nautical Almanac find for this date the moon's declination, moon's semidiameter, and moon's horizontal parallax, augmenting the moon's semidiameter for altitude. (Rules X., XII.) 3. Correct the observed altitude for index correction, dip, semidiameter, and parallax and refraction, and thus get the true altitude; subtract the true altitude from 90°, and thus get the true zenith distance. 4. Mark the zenith distance N. or S. according as the zenith is north or south of the moon. 5. Add together the declination and zenith distance, if they have the same names, but take their difference if their names be unlike, the result in each case will be the latitude, in the former of the name of either, in the latter of the name of the greater. EXAMPLES. November 12, 1853, at 2h 20m P.M., mean time nearly, in long. 60° 42′ W. observed the meridian altitude of the moon's lower limb to be 30° 30′ 40′′ (Z. N.), the index correction + 10′ 42′′, and height of eye above the sea 16 feet, required the latitude. -- (111.) Jan. 10, 1853, at 7h 40m P.M, mean time nearly, in long. 5° 30′ E., the observed meridian altitude of the moon's lower limb was 10° 20′ 30′′ (Z. N.), the index correction 2′ 20′′, and height of eye 14 feet, required the latitude. Ans., lat. 56° 37′ 46′′ N. (112.) Feb. 4, 1853, at 5h 40m A.M., mean time nearly, in long. 72° 18' W., the observed meridian altitude of the moon's lower limb was 40° 20′ 15′′ (Z. N.), index correction + 3′ 40′′, and height of eye 15 feet, required the latitude. Ans., lat. 25° 17′ 10′′ N. (113.) March 7, 1853, at 3h 20m P.M., mean time nearly, in long. 19° 20' W., the observed meridian altitude of the moon's lower limb was 19° 17′ 18′′ (Z. S.), index correction 1' 15", and height of eye 16 feet, required the latitude. Ans., lat. 88° 0′ 44′′ S. (114.) July 5, 1853, at 1h 7m P.M., mean time nearly, in long. 33° 30' E., the observed meridian altitude of the moon's upper limb was 25° 42′ 30′′ (Z. N.), the index correction +2′ 15′′, and height of eye 20 feet, required the latitude. Ans., lat. 88° 22′ 37′′ N. (115.) Aug. 12, 1853, at 5h 4m A.M., mean time nearly, in long. 94° 40′ E., the observed meridian altitude of the moon's upper limb was 72° 20' 0" (Z. S.), the index correction +3' 40", and height of eye 22 feet, required the latitude. Ans., lat. 31° 53′ 3′′ S. (116.) Dec. 27, 1853, at 9h 12m A.M., mean time nearly, in long. 15° 20′ W., the observed meridian altitude of the moon's upper limb was 19° 50′ 4′′ (Z. S.), the index correction 0' 30", and height of eye above the sea was 24 feet, required the latitude. Ans., lat. 87° 35′ 20′′ S. To find the latitude by the meridian altitude of a fixed star, and its declination. The declination of a fixed star changes so slowly, that we may, without any practical error, take it out of the Nautical Almanac by inspection; a Greenwich date will therefore be unnecessary. 1. Correct the observed altitude for index correction, dip, and refraction, and thus get the true meridian altitude: subtract this from 90° to obtain the true zenith distance. 2. Mark the same N. or S. according as the star is north or south of the zenith. 3. Take out the star's declination by inspection from the Nautical Almanac, and apply it to the true zenith distance in the manner pointed out in Rule XXVIII., Art. 5, and thus get the latitude. EXAMPLES. Feb. 10, 1853, the observed meridian altitude of a Hydræ was 35° 50′ 40′′ (zenith north of star), the index correction was 2′ 10′′, and height of eye 0 feet, required the (117.) May 21, 1853, the observed meridian altitude of a Bootis was 62° 42′ 10′′ (Z. N.), the index correction -44", and height of eye 18 feet, required the latitude. Ans., lat. 47° 23' 32" N. (118.) June 16, 1853, the observed meridian altitude of a Lyre was 77° 1' 50' (Z. N.), index correction + 2' 10", and height of eye 16 feet, required the latitude. Ans., lat. 51° 39′ 4′′ N. (119.) May 6, 1853, the observed meridian altitude of a Virginis was 16° 52′ 5′′ (Z. N.), index'correction + 1′ 45′′, and height of eye 20 feet, required the latitude. Ans., lat. 62° 50′ 4′′ N. (120.) Oct. 26, 1853, the observed meridian altitude of a Piscis Australis was 70° 10′ 0′′ (Z. S.), the index correction - 4' 5", and height of eye 10 feet, required the latitude. Ans., lat. 50° 21′ 23′′ S. (121.) May 10, 1853, the observed meridian altitude of a2 Centauri was 10° 4′ 15′′ (Z. N.), index correction and height of eye 20 feet, required the latitude. 2′ 10′′, Ans., lat. 9° 54′ 9′′ N. 4' 10", and (122.) Aug. 1, 1853, the observed altitude of a Aquila was 50° 4′ 15′′ (Z. N.), index correction height of eye 14 feet, required the latitude. Ans., lat. 48° 33′ 32′′ N. |