5. Calculating an altitude for an observation of lunar distance. The moon's meridian zenith-distance was 19° 20' 16" on February 27, in latitude N. 3° 42' 0"; what was its altitude at 7 h. 1 min. 27 sec. of mean time on the same day; the sid. time of mean noon being 22 h. 24 min. 47 sec.; moon's hor. par. 54′ 57′′. Observed transits Coll. Level 6. Finding the longitude on land by lunar transit. In latitude 51°23′36′′ 34 N., in February 1860, the following transits of the moon and ♪ Geminorum were observed in sidereal time. Az. Corrections for the Transit Instrument. I. To determine by observation the equatorial intervals of a transit instrument on January 12, 1860, in latitude 51°23′36 N., and longitude 2 min. 10 sec. E. Hence, for reduction to mean wire from centre wire add o'or when vertical circle is west and star above pole. 2. To determine the equatorial collimation error of the same instrument at the same place and date, also the level and azimuth errors. The inequality of pivots, a permanent portion of the level error, n this instrument amounted to o"03; the remainder of the error will vary with every observation. The equatorial collimation error (e) is constant for the same instrument. The azimuthal deviation (d) is the mean result of observations, and is practically a constant quantity. Observations on 8 Ursa Minoris. Star below pole. Levels () Corr. levels (7) Transits corr. for level Wires Obs. transits When the vertical circle E., and star above pole, it is -0*20. 3. Determining the corrections for the same instrument on February 10, 1860. Observations on 8 Ursa Minoris. Star below pole. When the vertical circle is W., and star below pole, it is + deviations E. of N., star S. of zenith. Taking the permanent means of the preceding corrections for the same instrument, without readjustment, they are For inequality of pivots, o".03. For equatorial collimation error, e= (0.20+006) = 0·13. For azimuthal deviation, d= (0·07+0·15)=0'II. In some other examples given, e is taken as =0'09 or 0·13. |