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The Method of Finding the Longitude at Sea, by Time-Keepers: To Which Are ...
No preview available - 2018
The Method of Finding the Longitude at Sea by Time-Keepers: To Which Are ...
No preview available - 2015
24 hours adjuſted againſt alſo altered its rate apparent noon aſſert aſſiſtant axis becauſe beſt caſe conſequently Correótion courſe decreaſes degrees diffe diſtance E X A M P L E eaſt elapſed elevated pole equation equinoćtial faſt finding the rate firſt limb firſt meridian fixed ſtar Fomalhaut glaſs half-interval horizon increaſes inſtant inſtru inſtrument interval laſt latitude leaſt leſs logarithm longitude for noon meridian moſt muſt Nautical Almanac neareſt neceſſary noon at Greenwich O's Long objećt obſervations obſerved difference ool or ool oppoſite parallax paſs paſſed perſons purpoſe rate of going repreſent reſpect reſt right aſcenſion ſail ſame ſcrew g ſea ſecant ſecond ſet ſextant ſhew ſhewn ſhip ſigns ſlow ſmall ſome ſouth ſpace ſtar's ſtill ſubjećt ſubtracted ſuch ſum ſun Sun's ſun's altitude ſun's declination ſun's longitude ſuppoſed teleſcope theſe thoſe time-keeper tion tranſit true altitude turn the ſcrew uſe weſt
Page 16 - 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 7 - 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 27 - 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 16 - 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 19 - 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 19 - 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 54 - 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 xiii - fhip is no otherwife an impediment in this fort of obfervations, than as it renders the repetition of them more