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The Method of Finding the Longitude at Sea by Time-Keepers: To Which Are ...
No preview available - 2015
15 degrees 24 hours altered its rate appa apparent noon axis Barbadoes Board of Longitude Co-latitude co-secant column deviation diffe earth east ecliptic equa EQUAL ALTITUDES equinoctial point exactly fast for mean finding the longitude finding the rate fixed star flow for mean Fomalhaut fun's glass half half-interval horizon instru interval latitude latter limb Log-rising logarithm longi longitude for noon mark the second mean solar mean solar day Merid meridian middle wire minutes Nautical Almanac nearest the elevated noon at Greenwich number of days O's Long observed difference opposite parallax in altitude Pegasi pivot F quicksilver rate of going Refraction rence screw g secant servation sextant shew shewn ship signs star's declination subtracted sun's altitude sun's declination sun's longitude sun's lower limb Take the difference taken tangent telescope time-keeper tion TRANSIT INSTRUMENT tube tude turning the screw watch gains watch goes
Page 18 - and the time correfponding to it will be the apparent time from the neareft noon: confequently, if the obfervation be made in the morning, the time thus found muft be taken from 24. hours, and the remainder will be the apparent time from the noon of the preceding day.
Page 9 - As the earth revolves uniformly on its axis, if it had no annual motion in its orbit, or if that motion was uniform, and in a plane
Page 29 - a telefcope, of any convenient length, fixed at right angles to an horizontal axis; on which it turns in the plane of the meridian,
Page 18 - latitude, and the logarithmic fecant of the fun's declination ; their fum,' rejecting 20 from the index, muft be fought for in Table XVI. under log-rifing, and the time correfponding to it will be the
Page 21 - it will always Ihew the mean time at the firft meridian. Hence, if the mean time be found at the ihip, by the preceding problem, the difference between it and the time
Page 21 - will continue to ihew the mean time at that meridian, as long as it continues to go at the fame rate, whatever place it may be carried to : and,
Page 56 - attend again to the watch. And in this manner the times when the fun's firft limb arrives at every one of the wires muft be obferved, and noted down in its proper column. The times when the fécond limb arrives at each of the five wires muft be obferved in the fame manner, and written in
Page xv - fhip is no otherwife an impediment in this fort of obfervations, than as it renders the repetition of them more