they_o be_v careful_a in_o the_o practic_n part_n of_o navigation_n it_o very_o often_o happen_v that_o one_o error_n correct_v another_o as_o for_o example_n suppose_v we_o err_v 4_o or_o 5_o minute_n in_o the_o lattitude_n 2_o or_o 3_o minute_n in_o the_o sun_n r._n a._n or_o dec._n in_o the_o day_n time_n 3_o or_o 4_o min._n in_o the_o star_n r._n a._n and_o about_o as_o many_o in_o its_o altitude_n it_o be_v ten_o to_o one_o odds_o but_o these_o error_n if_o not_o much_o great_a will_v so_o help_v to_o correct_v one_o another_o that_o you_o will_v come_v very_o near_o the_o true_a time_n of_o the_o day_n or_o night_n and_o what_o blockhead_n will_v trust_v to_o one_o observation_n when_o he_o can_v have_v the_o mean_v of_o 6_o or_o 8_o observation_n i_o account_v he_o a_o ignorant_a observer_n that_o err_v above_o 10_o or_o 12_o second_n of_o time_n day_n or_o night_n trust_v not_o to_o mr._n seller_n colson_n norwood_n newton_n table_n of_o the_o sun_n r._n a._n for_o for_o they_o be_v of_o no_o use_n in_o this_o case_n in_o observe_v the_o time_n of_o the_o night_n be_v very_o careful_a to_o find_v the_o sun_n r._n a._n true_a for_o want_v of_o good_a table_n of_o the_o sun_n place_n and_o r._n asc_n table_n of_o the_o sun_n place_n and_o declination_n may_v serve_v with_o a_o little_a more_o trouble_n for_o example_n anno_fw-la 1696_o march_v the_o 19_o at_o 3_o h_o a.m._n 30°_n to_o the_o westward_n of_o our_o first_o meridian_n i_o desire_v to_o know_v the_o sun_n r._n asc_n the_o table_n of_o the_o sun_n place_n and_o dec._n in_o most_o book_n of_o navigation_n want_v correction_n mr._n parker_n ephemeris_fw-la for_o this_o year_n give_v the_o sun_n place_n at_o noon_n in_o our_o first_o meridian_n 9°_n 44′_n ♈_o ☉_o dec._n 3°_n 51′_n n._n but_o 30°_n to_o the_o westward_n the_o ☉_o place_n at_o noon_n will_v in_o 9°_n 49′_n ♈_o and_o the_o ☉_o dec._n 3°_n 53′_n n._n if_o you_o consider_v the_o diurnal_a difference_n of_o the_o ☉_o place_n and_o dec._n you_o will_v find_v his_o place_n at_o the_o time_n propose_v to_o be_v in_o 9°_n 27_o ♈_o ☉_o dec._n 3°_n 44′_n n._n then_o have_v the_o ☉_o present_z dec._n say_v as_o rad._n to_o tang._n comp._n 23°_n 29′_n ☉_o great_a declination_n so_o be_v the_o tang._n 3°_n 44′_n the_o present_a dec._n to_o the_o sine_fw-la 8°_n 38′_n the_o ☉_o r._n a._n from_fw-la ♈_o at_o the_o time_n and_o place_n propose_v but_o there_o be_v a_o ready_a way_n have_v find_v the_o ☉_o place_n vide_fw-la astr_n car._n tabula_fw-la ascensionum_fw-la rectarum_fw-la and_o against_o the_o ☉_o place_n be_v the_o ☉_o r._n ascention_n etc._n etc._n this_o example_n i_o think_v fit_a to_o add_v for_o seman_n instruction_n in_o answer_n to_o the_o second_o objection_n that_o the_o theory_n of_o the_o moon_n motion_n be_v false_a it_o be_v not_o long_o ago_o since_o mr._n thomas_n street_n live_v among_o we_o who_o say_v as_o i_o have_v be_v inform_v that_o he_o be_v capable_a to_o perfect_v the_o theory_n of_o the_o moon_n motion_n so_o that_o her_o place_n may_v be_v as_o true_o find_v by_o calculation_n as_o any_o of_o the_o rest_n of_o the_o planet_n if_o he_o have_v encouragement_n it_o be_v ten_o thousand_o pity_n he_o have_v not_o but_o such_o be_v our_o english_a ingratitude_n there_o be_v now_o live_v in_o england_n two_o man_n that_o i_o believe_v be_v capable_a to_o perfect_v the_o theory_n of_o the_o moon_n motion_n which_o if_o either_o of_o they_o will_v be_v please_v to_o undertake_v as_o also_o to_o furnish_v we_o with_o large_a map_n of_o the_o fix_a star_n such_o as_o dr._n sprat_n be_v please_v to_o mention_v hist_o r._n s._n p._n 190._o i_o may_v be_v capable_a to_o practise_v and_o instruct_v other_o in_o the_o practic_n part_n of_o longitude_n at_o sea_n or_o the_o ingenious_a may_v put_v it_o to_o practice_n without_o my_o further_a assistance_n table_n of_o the_o moon_n place_n right_a ascension_n and_o declination_n will_v be_v please_v easie_n and_o more_o intelligible_a to_o our_o seaman_n if_o they_o be_v true_o calculate_v for_o noon_n or_o midnight_n in_o our_o first_o meridian_n but_o i_o think_v i_o can_v find_v as_o great_a objection_n as_o either_o of_o the_o former_a it_o be_v very_o difficult_a to_o contrive_v a_o instrument_n useful_a at_o sea_n for_o take_v the_o moon_n true_a distance_n from_o fix_a star_n for_o if_o you_o err_v but_o one_o minute_n of_o motion_n in_o the_o distance_n it_o will_v produce_v a_o error_n of_o about_o 28′_n in_o longitude_n and_o if_o the_o star_n place_n which_o you_o take_v your_o distance_n from_o happen_v to_o be_v one_o or_o two_o minute_n false_a the_o error_n will_v be_v so_o much_o the_o great_a also_o idleness_n be_v the_o root_n of_o ignorance_n and_o many_o other_o evil_n our_o mathematic_a schoolmaster_n that_o teach_v navigation_n most_o of_o their_o scholar_n when_o they_o come_v to_o sea_n be_v half_a to_o begin_v again_o a_o seaman_n have_v much_o nightwork_n as_o well_o as_o daywork_n it_o be_v convenient_a to_o go_v to_o school_n at_o night_n to_o learn_v to_o know_v the_o star_n how_o to_o find_v the_o time_n of_o the_o night_n by_o observation_n and_o how_o to_o find_v the_o moon_n place_n by_o observation_n i_o mean_v to_o practise_v it_o for_o example_n be_v best_a precept_n many_o able_a mathematician_n have_v write_v concern_v find_v the_o longitude_n by_o the_o moon_n eclipse_n concern_v which_o you_o may_v find_v many_o example_n in_o ph._n trans_fw-la of_o the_o royal_a society_n as_o also_o in_o a_o new_a system_fw-la of_o the_o mathematics_n by_o sir_n ionas_n more_o in_o the_o doctrine_n of_o the_o sphere_n to_o which_o i_o refer_v you_o it_o be_v more_o difficult_a to_o find_v the_o longitude_n by_o a_o eclipse_n of_o the_o sun_n then_o of_o the_o moon_n because_o that_o of_o the_o moon_n happen_v at_o one_o and_o the_o same_o time_n all_o over_o the_o world_n but_o a_o eclipse_n of_o the_o sun_n appear_v various_a in_o the_o various_a part_n of_o the_o earth_n the_o duration_n of_o a_o solar_a eclipse_n appear_v long_a in_o some_o place_n of_o the_o earth_n then_o in_o other_o therefore_o the_o end_n of_o a_o solar_a eclipse_n happen_v not_o at_o the_o same_o moment_n of_o time_n all_o over_o the_o world_n the_o superior_a planet_n suffer_v no_o eclipse_n when_o the_o earth_n come_v between_o they_o and_o the_o sun_n because_o the_o conical_a shadow_n of_o the_o earth_n can_v reach_v they_o anno_fw-la 1688_o october_n the_o 14_o 12°_n 40′_n mer._n do_v west_n plain_a chart_n from_o the_o mauritius_n i_o observe_v the_o sun_n eclipse_v at_o the_o end_n of_o the_o eclipse_n the_o ☉_o alt_z 27°_n 35′_n ☉_o dec._n 12°_n 3′_n s._n lat._n 31°_n 6′_n s._n will_v give_v the_o hour_n of_o the_o day_n 10_o h_o 33′_n 48″_n a._n m._n in_o our_o first_o meridian_n the_o end_n of_o the_o eclipse_n happen_v by_o some_o calculation_n at_o 7_o h_o 15′_n a._n m._n the_o difference_n be_v 3_o h_z 18′_n 48″_n convert_v into_o degree_n and_o minute_n give_v 49°_n 41′_n longitude_n east_n from_o our_o first_o meridian_n the_o penumbra_fw-la of_o the_o moon_n disk_n signify_v little_a or_o nothing_o astronomer_n make_v more_o ado_n about_o it_o then_o needs_o brother_n tar_n have_v a_o care_n of_o peep_v on_o a_o eclipse_n of_o the_o sun_n through_o a_o telescope_n for_o endanger_v the_o eyesight_n as_o i_o know_v one_o captain_n norgrave_n do_v i_o will_v tell_v thou_o the_o best_a way_n i_o know_v for_o observe_v eclipse_n of_o sun_n or_o moon_n take_v a_o looking-glass_n set_v it_o before_o thou_o so_o that_o thou_o may_v see_v the_o sun_n or_o moon_n by_o reflection_n on_o the_o glass_n then_o with_o a_o perspective_n or_o two_o or_o three_o foot_n telescope_n look_v on_o the_o looking-glass_n for_o the_o sun_n etc._n etc._n or_o you_o may_v have_v smoke_v or_o red_a glass_n to_o save_v the_o eyesight_n that_o the_o longitude_n may_v be_v find_v by_o the_o moon_n eclipse_v any_o of_o the_o rest_n of_o the_o planet_n or_o any_o know_a fix_a star_n be_v as_o certain_a as_o by_o eclipse_n of_o the_o sun_n or_o moon_n if_o mr._n halley_n be_v capable_a to_o observe_v the_o transit_fw-la of_o the_o sun_n and_o mercury_n as_o appear_v by_o these_o word_n viz._n schema_fw-la solis_fw-la ad_fw-la ingressum_fw-la mercurii_n st._n helena_n anno_fw-la 1677_o octob._n 28_o 9_o h_o 26′_n 40″_n p._n m._n sure_o with_o ordinary_a telescope_n we_o may_v be_v capable_a to_o observe_v when_o a_o star_n begin_v to_o culminate_v and_o limerge_n in_o or_o near_o the_o moon_n disk_n of_o or_o concern_v longitude_n by_o the_o moon_n approach_v and_o apulse_n to_o fix_a star_n this_o some_o think_v will_v be_v the_o most_o
practicable_a way_n for_o seaman_n yet_o mention_v when_o the_o theory_n of_o the_o moon_n motion_n be_v better_a know_v mr._n f._n have_v ingenious_o write_v to_o this_o purpose_n in_o his_o doctrine_n of_o the_o sphere_n annex_v to_o sir_n ionas_n moor_n system_n mathematics_n to_o which_o i_o advise_v you_o it_o be_v say_v that_o the_o moon_n move_v swift_a at_o new_a and_o full_a then_o at_o quarter_n to_o find_v the_o moon_n place_n by_o observation_n the_o most_o ingenious_a mathematical_a way_n be_v by_o take_v her_o distance_n from_o two_o know_a fix_a star_n see_v mr._n seller_n practical_a navigation_n the_o doctrine_n of_o the_o sphere_n problem_n 20._o but_o few_o seaman_n understand_v the_o affection_n and_o solution_n of_o spherical_a triangle_n that_o way_n be_v tedious_a and_o troublesome_a i_o know_v seaman_n care_v not_o to_o take_v so_o much_o pain_n beside_o the_o trouble_n of_o find_v the_o moon_n parallax_n and_o contrive_v instrument_n for_o take_v her_o exact_a distance_n from_o fix_a star_n the_o moon_n place_n may_v be_v find_v geometrical_o by_o scale_n and_o compass_n or_o on_o large_a map_n of_o the_o fix_a star_n first_o know_v her_o distance_n from_o any_o two_o know_a star_n in_o that_o map_n but_o a_o easy_a way_n be_v if_o we_o can_v contrive_v a_o instrument_n to_o take_v her_o difference_n of_o longitude_n from_o any_o fix_a star_n at_o one_o distance_n which_o i_o think_v not_o impossible_a especial_o when_o she_o be_v near_o the_o meridian_n or_o nonagesima_fw-la and_o then_o be_v the_o best_a time_n of_o observe_v illuminatio_fw-la lunae_fw-la per_fw-la solem._n see_v mr._n seller_n his_o atlas_n coelestibus_fw-la in_o the_o figure_n take_v from_o p._n gassendi_n institutio_fw-la astronomia_fw-la lib._n 2_o cap._n 26._o etc._n etc._n the_o moon_n be_v a_o round_a body_n and_o receive_v its_o light_n from_o the_o sun_n it_o follow_v that_o always_o one_o half_a of_o it_o yea_o somewhat_o more_o must_v be_v enlighten_v by_o he_o for_o see_v that_o the_o sun_n exceed_v the_o moon_n in_o bigness_n and_o that_o the_o big_a sphere_n always_o enlighten_v above_o half_a the_o less_o it_o do_v follow_v that_o above_o one_o half_a of_o the_o body_n of_o the_o moon_n must_v always_o be_v illuminate_v and_o see_v that_o the_o moon_n alter_v her_o position_n and_o in_o run_v about_o the_o earth_n do_v various_o face_n the_o sun_n it_o must_v needs_o be_v that_o according_a to_o its_o various_a access_n to_o or_o recess_n of_o the_o sun_n less_o or_o more_o of_o the_o illuminate_v half_a will_v appear_v to_o we_o which_o variation_n of_o her_o appearance_n be_v common_o call_v her_o phase_n the_o moon_n be_v never_o less_o enlighten_v then_o when_o she_o be_v at_o the_o full_a or_o in_o opposition_n with_o the_o sun_n because_o when_o she_o be_v full_a only_a that_o part_n towards_o we_o be_v enlighten_v whereas_o when_o new_a or_o in_o conjunction_n with_o the_o sun_n she_o be_v whole_o illuminate_v that_o part_n which_o be_v then_o towards_o we_o be_v enlighten_v by_o the_o earth_n and_o the_o other_o part_n that_o be_v turn_v from_o we_o by_o the_o sun_n for_o the_o moon_n do_v not_o only_o borrow_v her_o light_n from_o the_o sun_n but_o receive_v some_o weak_a illustration_n from_o the_o earth_n because_o the_o earth_n be_v a_o opake_v body_n must_v of_o necessity_n reflect_v part_n of_o her_o receive_a light_n and_o forasmuch_o as_o the_o earth_n be_v big_a than_o the_o moon_n consequent_o more_o light_a must_v be_v derive_v from_o the_o earth_n to_o the_o moon_n then_o from_o the_o moon_n to_o the_o earth_n this_o be_v confirm_v by_o experience_n because_o this_o secondary_a light_n as_o galilaeus_fw-la call_v it_o after_o the_o first_o quarter_n quite_o vanish_v by_o reason_n of_o the_o moon_n be_v too_o far_o distant_a and_o without_o the_o bound_n to_o which_o the_o reflect_a beam_n of_o the_o earth_n reach_v le_fw-fr grands_fw-fr body_n of_o philosophy_n see_v fig._n 30._o part_n 5._o chap._n 20._o now_o if_o the_o difference_n of_o the_o moon_n phase_n or_o the_o quantity_n of_o her_o illumination_n by_o the_o sun_n be_v mensurable_a by_o instrument_n than_o this_o method_n may_v happen_v to_o prove_v good_a for_o find_v the_o longitude_n in_o the_o ph._n tr_fw-la n._n 29._o p_o 451._o be_v a_o description_n of_o a_o instrument_n for_o divide_v a_o foot_n into_o many_o thousand_o part_n and_o thereby_o measure_v the_o diameter_n of_o the_o planet_n to_o great_a exactness_n etc._n etc._n also_o see_v ph._n tr_fw-la n._n 21._o p._n 373._o concern_v a_o way_n for_o take_v the_o diameter_n of_o the_o planet_n and_o for_o know_v the_o parallax_n of_o the_o moon_n etc._n etc._n the_o consideration_n hereof_o i_o humble_o recommend_v to_o the_o ingenious_a more_o especial_o to_o the_o royal_a society_n of_o london_n i_o have_v almost_o forget_v i_o desire_v you_o to_o take_v notice_n that_o one_o good_a map_n of_o the_o fix_a star_n may_v serve_v for_o ever_o without_o alteration_n save_o that_o it_o may_v decay_v in_o time_n which_o bad_a usage_n or_o a_o little_a alteration_n of_o the_o sun_n declination_n which_o be_v scarce_o worth_a our_o notice_n in_o one_o hundred_o year_n provide_v that_o either_o the_o equinoctial_a or_o the_o ecliptic_a line_n in_o those_o map_n be_v make_v to_o slide_v upon_o it_o and_o then_o it_o be_v only_o slide_v they_o a_o little_a every_o year_n according_a to_o the_o praecession_n of_o the_o aequinox_n the_o like_a aught_o to_o be_v consider_v in_o celestial_a globe_n and_o planisphere_n also_o one_o good_a table_n of_o the_o fix_a star_n place_n may_v serve_v for_o ever_o by_o add_v only_o the_o praecession_n of_o the_o aequinox_n chap._n vii_o longitude_n by_o jupiter_n satellite_n galilaeus_n in_o the_o year_n 1610_o the_o seven_o of_o january_n at_o the_o first_o hour_n of_o the_o night_n discover_v 4_o less_o planet_n about_o jupiter_n which_o like_o so_o many_o little_a moon_n be_v whirl_v round_o he_o those_o of_o they_o which_o be_v near_a to_o jupiter_n move_v more_o swift_o than_o those_o which_o be_v more_o remote_a the_o revolution_n of_o those_o secondary_a planet_n be_v thus_o calculate_v the_o innermost_a satellite_fw-la revolve_v to_o the_o sun_n in_o 1_o d_o 18_o h_o 28′_n 36″_n so_o precise_o that_o in_o 100_o year_n the_o difference_n be_v not_o sensible_a the_o period_n of_o the_o revolution_n of_o the_o other_o three_o satellite_n to_o jupiter_n shade_n be_v as_o follow_v  _fw-fr d_o h_o ′_o ″_o ‴_o period_n secundi_fw-la 3_o 13_o 17_o 54_o 3_o period_n tertii_fw-la 7_o 3_o 59_o 39_o 22_o period_n quaerti_n 16_o 18_o 5_o 6_o 50_o the_o attendant_n of_o jupiter_n whenever_o they_o enter_v the_o verge_n of_o his_o shadow_n do_v suffer_v a_o eclipse_n after_o the_o same_o manner_n as_o the_o moon_n do_v when_o she_o dip_v in_o the_o shadow_n of_o the_o earth_n and_o be_v total_o deprive_v of_o light_n as_o be_v opake_v body_n which_o borrow_v their_o light_n from_o the_o sun_n the_o 3_o first_o of_o these_o in_o every_o revolution_n produce_v 4_o eclipse_n the_o first_o when_o the_o satelles_fw-la enter_v into_o the_o rim_z of_o jupiter_n the_o second_o when_o the_o shadow_n of_o the_o satelles_fw-la do_v darken_v the_o rim_z of_o the_o say_a planet_n the_o three_o when_o the_o upper_a part_n of_o jupiter_n at_o his_o elongation_n from_o we_o do_v hide_v the_o satellite_n and_o the_o four_o when_o the_o satelles_fw-la dip_v in_o the_o shadow_n of_o jupiter_n so_o as_o that_o the_o first_o satelles_fw-la within_o the_o space_n of_o 7_o day_n do_v effect_n 16_o eclipse_n the_o second_o 8_o the_o three_o 4_o so_o that_o all_o of_o they_o together_o produce_v 28_o eclipse_n the_o four_o after_o that_o he_o have_v reach_v the_o nodes_fw-la do_v make_v 4_o eclipse_n in_o 17_o day_n but_o when_o near_o his_o bound_n he_o never_o suffer_v a_o defect_n of_o his_o light_n because_o his_o latitude_n be_v so_o large_a that_o he_o never_o touch_v the_o rim_z of_o jupiter_n or_o reach_v his_o shadow_n these_o eclipse_n be_v of_o great_a use_n in_o order_n to_o the_o determine_n of_o the_o longitude_n of_o place_n le_z grand_n philosophy_n but_o the_o eclipse_n for_o our_o purpose_n be_v only_o the_o immersion_n or_o emersion_n of_o the_o satellite_n in_o the_o verge_n of_o jupiter_n shade_n many_o there_o be_v who_o prefer_v this_o phaenomenon_n before_o other_o because_o the_o satellite_n of_o jupiter_n have_v no_o sensible_a parallax_n and_o in_o every_o position_n of_o jupiter_n above_o the_o horizon_n in_o the_o night_n when_o wether_n permit_v be_v convenient_o to_o be_v observe_v with_o a_o telescope_n of_o 12_o or_o 15_o foot_n long_o a_o fine_a dance_a instrument_n indeed_o at_o sea_n especial_o in_o a_o gale_n of_o wind_n than_o not_o manageable_a to_o look_v through_o a_o tube_n of_o 15_o or_o 18_o foot_n
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the_o sun_n refraction_n be_v great_a then_o near_o the_o equinoctial_a if_o the_o variation_n of_o the_o compass_n be_v better_o know_v and_o table_n of_o the_o variation_n for_o all_o the_o most_o note_a part_n in_o the_o world_n as_o headlands_n cape_n island_n etc._n etc._n the_o table_n calculate_v to_o a_o certain_a year_n because_o of_o the_o increase_n and_o decrease_v of_o the_o variation_n and_o the_o difference_n of_o the_o variation_n between_o those_o place_n then_o the_o knowledge_n thereof_o will_v be_v almost_o as_o good_a as_o the_o longitude_n know_v some_o few_o place_n except_v and_o if_o there_o be_v 10_o or_o 20_o year_n difference_n in_o lay_v or_o set_v down_o the_o variation_n in_o some_o place_n it_o matter_n not_o provide_v the_o year_n be_v set_v down_o when_o the_o variation_n be_v so_o much_o at_o such_o place_n and_o whether_o increase_v or_o decrease_v as_o for_o example_n suppose_v in_o the_o year_n 1708_o one_o shall_v happen_v to_o be_v 10_o or_o 12_o league_n south_n off_o of_o c._n b._n esperance_fw-fr and_o find_v the_o variation_n 12°_n 28′_n as_o i_o tell_v you_o before_o the_o difference_n of_o the_o variation_n between_o the_o say_a cape_n and_o st._n helena_n be_v 8°_n 56′_n by_o which_o rule_n when_o you_o be_v at_o the_o say_a cape_n you_o may_v know_v what_o the_o variation_n be_v at_o st._n helena_n viz._n 3°_n 32′_n both_o n._n westerly_n increase_v the_o like_a example_n may_v be_v consider_v of_o most_o other_o place_n in_o the_o world_n that_o be_v not_o above_o 20_o or_o 30°_n distant_a asunder_o except_o about_o the_o azore_n i_o present_v you_o with_o another_o method_n viz._n when_o we_o have_v such_o or_o such_o variation_n at_o london_n thereby_o to_o know_v what_o variation_n there_o be_v in_o any_o other_o part_n of_o the_o world_n for_o if_o at_o this_o present_a writing_n i_o know_v exact_o what_o variation_n there_o be_v in_o all_o part_n of_o the_o world_n i_o believe_v it_o will_v be_v no_o hard_a 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long_o which_o have_v only_o two_o glass_n in_o it_o and_o i_o have_v be_v trouble_v at_o sea_n to_o find_v a_o object_n with_o a_o perspective_n of_o 1_o foot_n and_o a_o half_a long_o which_o have_v only_o two_o glass_n in_o it_o therefore_o at_o sea_n for_o the_o better_a find_v a_o object_n we_o common_o use_v telescope_n with_o 3_o or_o 4_o glass_n in_o they_o of_o three_o or_o four_o foot_n long_o the_o telescope_n through_o which_o i_o have_v often_o look_v for_o jupiter_n but_o never_o can_v see_v his_o satellite_n through_o one_o of_o that_o length_n and_o what_o must_v we_o do_v for_o the_o longitude_n when_o jupiter_n rise_v and_o set_v cosmical_o or_o acronical_o as_o in_o september_n this_o year_n but_o we_o will_v suppose_v the_o best_a that_o the_o wether_n shall_v be_v so_o fair_a and_o sea_n smooth_a that_o we_o may_v possible_o get_v observation_n two_o or_o three_o time_n in_o a_o month_n indeed_o it_o will_v be_v a_o very_a great_a help_n and_o satisfaction_n to_o 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every_o year_n that_o be_v in_o the_o west_n and_o east-indies_n a_o late_a author_n in_o his_o book_n print_v anno_fw-la 1695_o have_v insert_v two_o year_n table_n for_o the_o time_n past_a viz._n 1693_o and_o 1694._o borrow_v perhaps_o out_o of_o some_o old_a ephemeris_fw-la it_o be_v well_o he_o say_v something_o of_o the_o time_n past_a its_o likely_a he_o know_v little_a or_o nothing_o of_o what_o be_v to_o come_v yet_o some_o of_o our_o able_a astronomer_n revile_v and_o reflect_v on_o our_o seman_n ignorance_n because_o the_o seaman_n as_o they_o say_v can_v find_v the_o longitude_n indeed_o i_o think_v our_o seaman_n have_v most_o cause_n to_o rail_v at_o our_o mathematician_n that_o have_v do_v nothing_o as_o i_o know_v of_o to_o any_o purpose_n for_o the_o encouragement_n or_o improvement_n of_o navigation_n for_o almost_o 20_o year_n past_a except_o a_o tide_n table_n as_o i_o shall_v prove_v by_o sellers_n practical_a navigation_n the_o most_o useful_a book_n for_o seaman_n yet_o extant_a and_o the_o impression_n worse_o now_o than_o it_o be_v almost_o 20_o year_n ago_o compare_v the_o table_n of_o the_o sun_n place_n and_o declination_n in_o the_o seven_o edition_n of_o the_o practical_a navigation_n with_o table_n of_o the_o sun_n place_n and_o declination_n in_o parker_n ephemeris_fw-la for_o this_o year_n and_o you_o will_v find_v considerable_a difference_n and_o that_o the_o impression_n be_v better_a 18_o or_o 20_o year_n ago_o i_o prove_v by_o pag._n 330_o viz._n a_o table_n of_o the_o variation_n of_o the_o sun_n declination_n to_o be_v apply_v for_o year_n to_o come_v etc._n etc._n if_o the_o table_n be_v the_o same_o as_o in_o anno_fw-la 1680_o or_o thereabouts_o we_o may_v by_o the_o say_a table_n of_o variation_n have_v correct_v the_o table_n of_o the_o sun_n declination_n but_o there_o be_v impose_v on_o we_o new_a date_n of_o year_n etc._n etc._n the_o aforesaid_a book_n want_v correction_n very_o much_o there_o be_v want_v in_o it_o a_o large_a table_n of_o difference_n of_o latitude_n and_o departure_n such_o a_o one_o as_o be_v in_o colson_n calendar_n the_o table_n of_o the_o sun_n right_a ascension_n aught_o to_o be_v more_o large_a and_o calculate_v to_o degree_n and_o minute_n to_o a_o certain_a year_n etc._n etc._n pardon_v this_o digression_n now_o to_o our_o purpose_n again_o since_o we_o be_v unfurnished_v with_o fit_v table_n of_o all_o the_o say_a satellite_n i_o recommend_v you_o to_o the_o best_a i_o know_v of_o viz._n see_v ph._n trans_fw-la n._n 214_o p._n 237._o to_o 256._o mounseur_fw-fr cassini_n his_o new_a and_o exact_a table_n for_o the_o eclipse_n of_o the_o first_o satellite_fw-la of_o jupiter_n reduce_v to_o the_o julian_n style_n and_o meridian_n of_o london_n etc._n etc._n but_o in_o calculate_v the_o eclipse_n of_o the_o satellite_fw-la by_o the_o say_a table_n there_o sometime_o happen_v a_o error_n of_o 3_o or_o 4_o minute_n of_o time_n i_o believe_v i_o know_v how_o to_o correct_v that_o error_n though_o it_o have_v baffle_v the_o ingenious_a and_o will_v a_o do_v it_o here_o if_o it_o have_v no_o require_a figure_n or_o cut_v for_o demonstration_n saturn_n have_v also_o five_o satellite_n attend_v he_o but_o be_v not_o account_v so_o worthy_a our_o notice_n for_o the_o longitude_n as_o the_o former_a therefore_o i_o pass_v they_o in_o silence_n the_o sun_n jupiter_n and_o all_o the_o rest_n except_o the_o moon_n of_o the_o planet_n have_v a_o circumrotation_n in_o their_o own_o proper_a vortex_n as_o telescopial_n observation_n testify_v by_o several_a spot_n that_o appear_v in_o their_o phase_n perchance_o it_o may_v be_v say_v why_o have_v not_o i_o furnish_v this_o book_n with_o regular_a table_n of_o the_o moon_n motion_n and_o of_o jupiter_n satellite_n it_o will_v be_v a_o very_a unreasonable_a demand_n to_o require_v they_o from_o a_o man_n that_o have_v want_v both_o book_n and_o instrument_n till_o now_o also_o convenience_n and_o opportunity_n have_v only_o a_o small_a cabin_n sometime_o not_o high_a enough_o to_o stand_v upright_o in_o nor_o my_o length_n to_o lie_v down_o in_o insomuch_o that_o i_o have_v be_v oblige_v to_o borrow_v both_o book_n and_o instrument_n for_o the_o common_a practice_n of_o navigation_n beside_o the_o circumstance_n of_o my_o employ_v and_o many_o other_o inconvenience_n that_o may_v and_o do_v attend_v such_o study_n and_o observation_n i_o will_v conclude_v this_o chapter_n with_o the_o follow_a word_n which_o i_o take_v to_o be_v the_o ingenious_a mr._n flamstead'_v viz._n as_o by_o lunar_a eclipse_n so_o also_o by_o the_o eclipse_n of_o jupiter_n satellite_n the_o difference_n of_o the_o observe_v moment_n of_o the_o occultation_n or_o emersion_n of_o a_o satellite_fw-la from_o his_o shadow_n note_v careful_o in_o two_o distant_a place_n will_v be_v the_o difference_n of_o meridian_n betwixt_o these_o two_o place_n in_o time_n but_o i_o can_v hope_v that_o this_o method_n shall_v prove_v of_o much_o use_n to_o the_o ingenious_a seaman_n because_o the_o observation_n require_v long_a telescope_n which_o in_o a_o ship_n will_v hardly_o be_v manageable_a nor_o can_v we_o expect_v to_o find_v the_o difference_n of_o meridian_n by_o one_o only_a observation_n of_o a_o satellite_fw-la eclipse_n as_o we_o have_v hope_n we_o may_v by_o a_o lunar_a by_o reason_n that_o as_o yet_o the_o inequality_n of_o their_o motion_n and_o the_o time_n require_v for_o the_o transmission_n of_o light_n from_o the_o planet_n to_o our_o earth_n be_v unknown_a nay_o their_o mean_a motion_n be_v scarce_o so_o exact_o state_v but_o that_o we_o may_v just_o suspect_v they_o erroneous_a omit_v these_o therefore_o the_o best_a method_n for_o the_o discovery_n of_o the_o longitude_n will_v be_v in_o my_o opinion_n i_o be_o dubious_a he_o be_v now_o of_o another_o opinion_n by_o the_o moon_n apulse_n to_o or_o observe_v distance_n from_o fix_a star_n upon_o which_o accoun_n i_o will_v recommend_v the_o improvement_n and_o correction_n of_o her_o theory_n with_o the_o doctrine_n and_o construction_n of_o apulse_n to_o the_o study_n of_o the_o ingenious_a astronomer_n and_o seaman_n humanum_fw-la est_fw-la errare_fw-la i_o have_v almost_o forget_v mr._n newton_n have_v contrive_v a_o instrument_n for_o his_o own_o use_n to_o see_v jupiter_n satellite_n by_o reflection_n on_o well_o polish_a mettle_n the_o instrument_n be_v about_o 15_o inch_n long_o as_o some_o say_v other_z 9_o or_o 10_o inch_n and_o call_v it_o a_o reflect_a telescope_n i_o be_o inform_v it_o be_v of_o little_a or_o no_o use_n i_o have_v not_o see_v any_o of_o they_o therefore_o can_v give_v you_o no_o better_a description_n i_o also_o add_v to_o tell_v some_o master_n of_o of_o jupiter_n satellite_n be_v like_o tell_v a_o story_n to_o a_o bear_n they_o know_v better_o how_o to_o manage_v a_o cann_n of_o