before_o lay_v down_o in_o the_o rectification_n of_o the_o quadrant_n we_o be_v to_o find_v the_o quantity_n of_o this_o erroneous_a angle_n and_o to_o allow_v for_o it_o in_o observation_n in_o instrument_n furnish_v with_o two_o pair_n of_o telescopick-sight_n sight_n one_o on_o a_o fix_a arm_n and_o other_o on_o a_o movable_a arm_n by_o the_o ancient_n term_v a_o alidade_fw-mi it_o be_v easy_a rectify_v the_o sight_n on_o the_o movable_a arm_n thus_o after_o the_o sight_n on_o the_o fix_a arm_n be_v rectify_v by_o what_o forego_v bring_v the_o index_n of_o the_o movable_a arm_n to_o the_o begin_n of_o the_o division_n on_o the_o limb_n of_o the_o instrument_n be_v it_o quadrant_n or_o sextant_a etc._n etc._n it_o be_v then_o manifest_a that_o the_o line_n of_o collimation_n through_o the_o movable_a telescope_n if_o it_o be_v right_a shall_v lie_v parallel_n to_o the_o line_n of_o collimation_n through_o the_o fix_a telescope_n observe_v therefore_o whether_o the_o cross-hair_n in_o both_o telescope_n do_v at_o the_o same_o time_n cut_v the_o same_o star_n or_o fall_v on_o the_o same_o point_n in_o a_o object_n distant_a three_o or_o four_o mile_n if_o they_o do_v than_o the_o movable_a telescope_n agree_v with_o the_o fix_a and_o the_o fix_a being_n suppose_v rectify_v to_o the_o division_n on_o the_o instrument_n the_o movable_a be_v right_o likewise_o but_o if_o the_o hair_n in_o the_o movable_a telescope_n do_v not_o agree_v in_o make_v the_o same_o point_n with_o the_o cross-hair_n in_o the_o fix_a telescope_n then_o the_o hair_n in_o this_o movable_a telescope_n be_v to_o be_v remove_v by_o whatever_o contrivance_n there_o be_v for_o that_o purpose_n and_o bring_v to_o right_n and_o there_o fix_v there_o be_v other_o method_n propound_v for_o rectify_v telescopick-sight_n on_o other_o sort_n of_o instrument_n by_o mean_n of_o observation_n towards_o the_o zenith_n as_o our_o former_a method_n have_v be_v employ_v towards_o the_o horizon_n but_o it_o be_v sufficient_a here_o to_o lay_v down_o only_o what_o forego_v as_o be_v of_o the_o great_a and_o most_o frequent_a use_n refer_v for_o the_o other_o to_o m._n picardâ—_n s_o treatise_n of_o the_o measure_n of_o a_o degree_n of_o a_o great_a circle_n of_o the_o earth_n publish_v at_o the_o end_n of_o memoir_n for_o a_o natural_a history_n of_o animal_n etc._n etc._n by_o the_o academy_n royal_a at_o paris_n late_o translate_v into_o english_a and_o print_v at_o london_n 1688._o fol._n before_o i_o quit_v this_o point_n telescopick-ruler_n it_o may_v not_o be_v amiss_o to_o intimate_v one_o use_n to_o which_o a_o plain_a ruler_n furnish_v with_o telescopick-sight_n such_o as_o be_v express_v tab._n 39_o fig._n 3._o may_v be_v apply_v and_o that_o be_v not_o only_o for_o try_v the_o exquisite_a straitness_n of_o either_o of_o its_o own_o edge_n and_o parallelism_n of_o its_o own_o two_o side_n but_o also_o for_o the_o ready_a trial_n of_o the_o same_o in_o any_o other_o ruler_n for_o it_o be_v but_o affix_v by_o a_o little_a cement_n or_o otherwise_o this_o telescopick-ruler_n over_o the_o ruler_n to_o be_v try_v and_o rest_v the_o edge_n of_o this_o latter_a against_o the_o pin_n h_o i_o and_o gentle_o slide_v the_o edge_n alongst_o these_o pin_n and_o always_o touch_v they_o look_v all_o the_o while_n through_o the_o telescope_n observe_v whether_o the_o cross-hair_n do_v steady_o adhere_v to_o the_o same_o point_n in_o a_o object_n for_o if_o the_o edge_n of_o the_o ruler_n have_v the_o least_o irregular_a crookedness_n thâ—_n cross-hair_n will_v move_v from_o the_o point_n first_o observe_v and_o this_o shall_v detect_v the_o least_o curvity_n in_o the_o edge_n of_o a_o ruler_n especial_o if_o the_o ruler_n be_v long_o and_o the_o distance_n of_o the_o pin_n be_v considerable_a that_o shall_v escape_v the_o most_o exquisite_a eye_n of_o a_o workman_n the_o way_n of_o try_v the_o parallelism_n of_o the_o two_o side_n of_o this_o latter_a ruler_n be_v the_o same_o with_o what_o forego_v for_o the_o telescopick-ruler_n itself_o for_o when_o the_o telescopick-ruler_n be_v adjoin_v over_o the_o other_o they_o may_v both_o be_v take_v but_o as_o one_o ruler_n with_o telescope-sight_n affix_v 6._o i_o come_v now_o to_o the_o last_o thing_n propose_v concern_v telescopick-sight_n performance_n and_o that_o be_v to_o show_v the_o dioptrick-reason_n of_o their_o performance_n and_o exactness_n but_o herein_o there_o will_v be_v little_o requisite_a to_o be_v add_v to_o what_o forego_v both_o in_o the_o first_o part_n concern_v telescope_n in_o general_a and_o to_o what_o be_v lay_v down_o in_o this_o chapter_n concern_v telescopick-sight_n it_o be_v manifest_a by_o experiment_n that_o the_o ordinary_a power_n of_o man_n eye_n extend_v no_o far_a than_o perceive_v what_o subtend_v a_o angle_n of_o about_o a_o minute_n or_o something_o less_o but_o when_o a_o eye_n be_v arm_v with_o a_o telescope_n it_o may_v discern_v a_o angle_n less_o than_o a_o second_o the_o telescope_n that_o magnify_v distinct_o the_o appearance_n of_o body_n magnify_v also_o distinct_o the_o appearance_n of_o extension_n space_n and_o motion_n through_o this_o space_n so_o if_o the_o minute-hand_n of_o a_o watch_n which_o can_v but_o just_a be_v perceive_v to_o move_v be_v look_v upon_o with_o a_o magnifying-glass_n we_o shall_v see_v it_o give_v a_o considerable_a leap_n at_o every_o stroke_n of_o the_o balance_n and_o thus_o likewise_o the_o slow_a diurnal_a motion_n of_o the_o sun_n or_o star_n which_o be_v hardly_o perceivable_a by_o the_o bare_a eye_n unless_o assist_v by_o a_o instrument_n of_o a_o vast_a radius_fw-la be_v most_o easy_o perceive_v through_o a_o ordinary_a telescope_n of_o 18_o inch_n long_o insomuch_o that_o we_o may_v determine_v to_o the_o great_a niceity_n and_o exactness_n when_o a_o star_n pass_v just_a over_o the_o cross-hair_n even_o to_o the_o single_a beat_n of_o a_o second-pendulum_a and_o let_v a_o object_n in_o the_o heaven_n rise_v never_o so_o little_a the_o image_n in_o the_o distinct-base_a fall_v correspondent_o at_o the_o cross-hair_n and_o the_o eye_n by_o mean_n of_o the_o eye-glass_n perceive_v this_o motion_n be_v it_o never_o so_o small_a thus_o suppose_v tab._n 39_o fig._n 1â—_n that_o a_o star_n rise_v from_o b_o to_o a_o the_o image_n fall_v at_o the_o cross-hair_n in_o the_o distinct_a base_a from_o e_z to_z d_o then_o by_o mean_n of_o the_o eye-glass_n o_o p_o the_o space_n e_o d_o be_v might_o magnify_v and_o consequent_o the_o angle_n b_o c_o a_o equal_a to_o e_o c_o d_o by_o which_o the_o star_n be_v rise_v be_v make_v most_o sensible_a to_o the_o eye_n q._n by_o whatforegoe_v in_o the_o first_o part_n concern_v the_o magnify_n of_o this_o sort_n of_o telescope_n by_o this_o we_o may_v perceive_v how_o the_o noble_a hevelius_n manifest_v be_v mistake_v in_o his_o estimate_n of_o these_o sight_n when_o he_o imagine_v the_o line_n of_o collimation_n therein_o be_v no_o long_a than_o between_o the_o cross-hair_n and_o eye-glass_n whereas_o this_o distance_n be_v not_o at_o all_o to_o be_v consider_v in_o their_o performance_n the_o line_n of_o collimation_n be_v full_a as_o long_o as_o the_o distance_n between_o the_o object-glass_n and_o cross-hair_n i_o be_o persuade_v have_v he_o be_v rectify_v in_o this_o particular_a he_o will_v never_o have_v adhere_v so_o obstinate_o to_o the_o use_v of_o plain_a sight_n upon_o his_o most_o costly_a instrument_n though_o i_o must_v confess_v it_o be_v difficult_a to_o wean_v a_o man_n from_o the_o use_n of_o what_o he_o have_v be_v accustom_v to_o for_o so_o many_o year_n and_o upon_o the_o exactness_n of_o which_o the_o accuracy_n of_o all_o his_o former_a labour_n do_v depend_v as_o to_o all_o other_o objection_n which_o he_o make_v against_o they_o answer_v as_o that_o they_o be_v easy_o disorder_v that_o the_o glass_n be_v easy_o vitiate_v by_o the_o breath_n of_o the_o observer_n etc._n etc._n they_o be_v not_o of_o any_o the_o least_o moment_n for_o it_o be_v manifest_a they_o may_v be_v contrive_v so_o as_o to_o be_v more_o secure_a and_o less_o subject_a to_o injury_n than_o any_o other_o plain_a sight_n whatsoever_o and_o in_o this_o particular_a telescope-sight_n be_v so_o far_o from_o be_v obnoxious_a that_o certain_o they_o be_v preferable_a to_o the_o best_a contrive_a plain_a sight_n for_o what_o can_v be_v more_o simple_a and_o easy_a preserve_v than_o the_o forementioned_a small_a but_o strong_a brass_n ring_v defend_v by_o a_o tin_n or_o brassâ—_n tube_n cover_v all_o when_o once_o these_o be_v adjust_v and_o fix_v nothing_o can_v possible_o injure_v they_o it_o be_v true_a the_o breath_n of_o the_o observer_n if_o puff_v into_o the_o telescope_n will_v full_o the_o eye-glass_n but_o how_o easy_o be_v this_o avoid_v who_o be_v it_o go_v purposely_o to_o make_v a_o speaking-trumpet_n of_o a_o
the_o reason_n say_v he_o that_o the_o appearance_n through_o glass_n of_o the_o change_n of_o the_o object_n place_v do_v not_o so_o strong_o strike_v the_o sense_n as_o the_o doctrine_n here_o lay_v down_o seem_v to_o intimate_v proceed_v from_o hence_o that_o optick-glass_n be_v seldom_o or_o never_o make_v so_o large_a as_o to_o be_v look_v through_o by_o both_o eye_n at_o once_o for_o if_o they_o be_v he_o assert_n that_o the_o locus_fw-la apparens_fw-la objecti_fw-la will_v be_v much_o more_o plain_o and_o sensible_o determine_v to_o the_o sight_n in_o this_o particular_a certain_o he_o be_v much_o in_o the_o right_a for_o we_o see_v at_o all_o time_n that_o two_o eye_n make_v a_o more_o exact_a estimate_n of_o the_o position_n of_o a_o object_n than_o one_o single_a eye_n and_o we_o have_v a_o sensible_a experiment_n hereof_o in_o catoptric_n by_o the_o large_a concave_a miroirs_n where_o a_o hand_n and_o dagger_n present_v beyond_o the_o focus_n seem_v to_o strike_v far_o without_o the_o speculum_fw-la at_o he_o that_o present_v it_o but_o not_o so_o strong_o if_o the_o speculum_fw-la be_v but_o small_a so_o that_o the_o image_n can_v be_v see_v but_o by_o one_o eye_n at_o once_o scholium_fw-la to_o this_o property_n of_o the_o change_n of_o the_o apparent_a place_n of_o a_o object_n may_v we_o attribute_v that_o common_a effect_n of_o object_n seem_v to_o dance_n and_o move_v be_v see_v through_o spherick-glass_n whether_o convex_a or_o concave_a nimble_o shake_v between_o the_o eye_n and_o the_o object_n it_o be_v a_o note_a experiment_n that_o to_o know_v whether_o a_o glass_n be_v plain_a or_o spherical_a which_o be_v not_o to_o be_v find_v by_o inspection_n of_o the_o glass_n itself_o or_o by_o touch_n if_o the_o glass_n he_o form_v on_o large_a sphere_n and_o be_v but_o small_a portion_n thereof_o the_o common_a trial_n be_v to_o shake_v they_o something_o nimble_o between_o the_o eye_n and_o a_o object_n and_o if_o the_o object_n seem_v to_o move_v by_o the_o motion_n of_o the_o glass_n the_o glass_n be_v not_o plain_a the_o reason_n hereof_o be_v this_o that_o towards_o the_o extremity_n of_o a_o glass_n the_o glass_n refract_v more_o than_o towards_o the_o middle_n for_o the_o very_a middle_a ray_n that_o be_v perpendicular_a be_v not_o refract_v at_o all_o and_o consequent_o the_o apparent_a place_n of_o a_o object_n be_v more_o change_v by_o the_o refraction_n in_o the_o extreme_a part_n of_o the_o glass_n than_o in_o the_o middle_n of_o the_o glass_n so_o that_o the_o object_n by_o the_o motion_n of_o the_o glass_n appear_v sometime_o through_o the_o middle_n of_o the_o glass_n sometime_o through_o the_o extremity_n of_o the_o glass_n the_o apparent_a place_n thereof_o be_v vary_v likewise_o and_o the_o object_n seem_v therefore_o to_o change_v its_o place_n or_o to_o move_v but_o in_o a_o plain_a glass_n the_o case_n be_v otherwise_o for_o the_o refraction_n thereof_o be_v equal_o prevalent_a throughout_o the_o whole_a glass_n and_o neither_o strong_a nor_o weak_a in_o the_o middle_n than_o in_o the_o extremity_n so_o that_o the_o shake_n of_o it_o between_o the_o eye_n and_o object_n make_v no_o other_o difference_n in_o the_o apparent_a place_n than_o if_o the_o glass_n be_v look_v through_o fix_v and_o immovable_a and_o therefore_o the_o object_n seem_v not_o through_o it_o to_o shake_v and_o move_v and_o though_o the_o locus_n be_v change_v by_o a_o spheric_a glas_n be_v remove_v to_o and_o from_o the_o eye_n yet_o in_o glass_n of_o large_a sphere_n the_o locus_n be_v not_o so_o sensible_o change_v as_o by_o be_v shake_v before_o the_o eye_n the_o same_o reason_n hold_v for_o the_o apparent_a dance_a of_o object_n see_v through_o rise_a smoke_n or_o vapour_n prop._n xxxii_o a_o object_n be_v place_v in_o the_o focus_n of_o a_o convex-glass_n and_o the_o eye_n on_o other_o side_n the_o glass_n see_v this_o object_n distinct_o and_o erect_v that_o a_o object_n so_o posit_v be_v see_v distinct_o be_v evident_a because_o the_o ray_n from_o each_o particular_a point_n after_o pass_v the_o glass_n become_v parallel_n by_o prop._n vi_o and_o so_o fall_v on_o the_o eye_n and_o therefore_o by_o prop._n xxviii_o sec._n 7._o they_o be_v fit_a to_o cause_v distinct_a vision_n tab._n 27._o fig._n 3._o 3._o the_o point_n a_o send_v forth_o its_o diverge_a ray_n a_o c_o a_o d_o on_o the_o convex-glass_n c_o d_o these_o be_v transmit_v by_o the_o glass_n parallel_n in_o c_o e_o d_o g_o and_o so_o fall_v on_o the_o eye_n by_o who_o coar_n and_o humour_n especial_o by_o the_o crystalline_a h_o i_o they_o be_v refract_v and_o bring_v together_o in_o the_o point_n k_o on_o the_o retina_fw-la there_o represent_v distinct_o the_o point_n a_o of_o the_o object_n or_o thus_o tab._n 28._o fig._n 1._o 1._o the_o eye_n o_o p_o be_v in_o the_o place_n where_o some_o of_o the_o ray_n from_o every_o point_n in_o the_o object_n be_v mix_v together_o be_v in_o the_o place_n of_o the_o great_a confusion_n and_o therefore_o by_o prop._n xxviii_o sec._n 3._o the_o vision_n be_v distinct_a i_o say_v also_o the_o object_n be_v see_v erect_v in_o the_o same_o figure_n g_o k_o be_v a_o convex-glass_n a_o b_o c_o a_o object_n we_o may_v imagine_v that_o each_o point_n of_o this_o object_n send_v from_o it_o a_o cone_n of_o ray_n fall_v on_o the_o whole_a surface_n of_o the_o glass_n but_o for_o avoid_v confusion_n in_o the_o scheme_n i_o only_o express_v and_o consider_v the_o ray_n c_o g_o c_o h_o from_o the_o point_n c_o and_o a_o k_o a_o i_o from_o the_o point_n aâ—_n o_o p_o be_v the_o crystalline_a of_o the_o eye_n the_o ray_n c_o g_o c_o h_o after_o pass_v the_o glass_n become_v parallel_n as_o g_o o_fw-fr h_o p_o and_o fall_v so_o on_o the_o crystalline_a by_o who_o refraction_n they_o be_v again_o bring_v together_o in_o the_o point_n d_o on_o the_o retina_fw-la there_o paint_v the_o lively_a representation_n of_o the_o point_n c_o and_o the_o same_o may_v be_v show_v of_o the_o representation_n of_o the_o point_n a_o at_o f_o on_o the_o retina_fw-la wherefore_o the_o smister_n point_fw-fr c_o be_v represent_v on_o the_o dexter_a part_n of_o the_o fund_z of_o the_o eye_n d_o and_o the_o dexter_a part_n of_o the_o object_n a_o be_v paint_v on_o the_o smister_n part_n of_o the_o eye_n f._n and_o consequent_o the_o image_n on_o the_o retina_fw-la be_v invert_v the_o object_n be_v see_v erect_v by_o prop._n xxviii_o sec._n 4_o 5._o which_o be_v to_o be_v demonstrate_v prop._n xxxiii_o a_o object_n be_v place_v in_o the_o focus_n of_o a_o convex_a glass_n and_o the_o eye_n be_v place_v in_o the_o focus_n on_o other_o side_n the_o glass_n see_v this_o object_n under_o the_o same_o angle_n as_o be_v the_o naked_a eye_n place_v at_o the_o station_n of_o the_o glass_n tab._n 28._o fig._n 2._o 2._o a_o x_o b_o be_v a_o object_n place_v in_o the_o focus_n of_o the_o glass_n e_o f_o which_o we_o suppose_v of_o the_o least_o thickness_n imaginable_a let_v the_o ray_n a_o e_o b_o f_o run_v parallel_n to_o the_o axis_n x_o c_o o_o these_o ray_n be_v unite_v in_o the_o focus_n at_o o_o at_o which_o point_n we_o suppose_v the_o eye_n produce_v o_o e_o and_o o_o f_o directly_z to_z g_o and_o k_o and_o draw_v e_o c_o f_o which_o by_o supposition_n be_v parallel_n to_o a_o x_o b_o and_o then_o draw_v a_o c_o b_o c._n the_o optick-angle_n through_o the_o glass_n be_v e_o o_o f_o which_o we_o be_v to_o prove_v equal_a to_o a_o c_o b._n thus_o a_o x_o and_o e_o c_o being_n parallel_n and_o a_o e_o x_o c_o be_v so_o likewise_o a_o x_o be_v equal_a to_o e_o c_o and_o a_o e_o to_o x_o c_o be_v the_o opposite_a side_n of_o a_o parallelogram_n but_o x_o c_o be_v equal_a to_z c_o o_fw-fr the_o focal_a length_n on_o one_o side_n and_o tother_o wherefore_o the_o right-angled_n triangle_n e_o c_o o_fw-fr be_v equal_a and_o similar_v to_o the_o right-angled_n triangle_n a_o x_o c._n wherefore_o the_o angle_n e_o o_o c_o be_v equal_a to_o the_o angle_n a_o c_o x_o or_o e_o o_o f_o be_v equal_a to_o a_o c_o b._n and_o consequent_o the_o eye_n at_o o_o see_v the_o object_n through_o the_o glass_n under_o the_o same_o angle_n as_o the_o naked_a eye_n be_v place_n at_o c_o will_v see_v it_o which_o be_v to_o be_v prove_v vid._n gregorii_n opt._n prom._n prop._n xliv_o scholium_fw-la this_o be_v the_o posture_n of_o both_o eye_n and_o object_n for_o cause_v the_o most_o perfect_a vision_n possible_a through_o a_o single_a convex_a glass_n unless_o perhaps_o we_o say_v that_o see_v all_o object_n which_o we_o perceive_v most_o distinct_o be_v pretty_a nigh_o our_o eye_n therefore_o we_o may_v conceive_v the_o
true_a respective_a focus_n but_o if_o we_o believe_v the_o say_v mons._n auzout_o by_o this_o way_n if_o this_o way_n which_o i_o propose_v be_v his_o as_o i_o know_v not_o whether_o it_o be_v or_o not_o one_o come_v near_o enough_o to_o exactness_n and_o perhaps_o as_o just_a as_o by_o most_o of_o the_o method_n ordinary_o use_v however_o though_o the_o practice_n through_o some_o accidental_a difficulty_n do_v not_o so_o exact_o answer_v the_o theory_n yet_o it_o can_v be_v deny_v that_o the_o theory_n be_v true_a and_o perhaps_o far_a improvement_n may_v bring_v it_o to_o perfection_n chap._n vii_o a_o optic_a problem_n of_o double_a vision_n in_o tab._n 4â—_n fig._n 1._o 〈◊〉_d a_o b_o be_v the_o two_o eye_n c_o the_o nigh_a object_n d_o the_o far_a object_n if_o both_o eye_n open_a be_v fix_v upon_o c_o the_o object_n d_o shall_v seem_v double_a and_o then_o shut_v the_o left_a eye_n a_o the_o left_a image_n of_o d_o disappear_v and_o shut_v the_o right_a eye_n b_o the_o right_a image_n of_o d_o disappear_v but_o if_o both_o eye_n open_a be_v fix_v on_o d_o then_z c_z shall_v seem_v double_a and_o if_o the_o left_a eye_n a_o be_v shut_v the_o right_a image_n of_o c_o vanish_v if_o the_o right_a eye_n b_o be_v shuâ—_n the_o left_a image_n of_o c_o vanishes_z this_o be_v the_o declaration_n of_o the_o phaenomenon_n which_o any_o one_o may_v experiment_n by_o place_v two_o candle_n d_o 3_o foot_n and_o c_o 1_o foot_n distant_a from_o the_o eye_n and_o then_o stand_v so_o that_o the_o nose_n and_o two_o object_n may_v lie_v in_o or_o near_o a_o right_a line_n he_o fix_v his_o eye_n on_o either_o object_n alternate_o open_a and_o shut_v they_o i_o choose_v two_o candle_n and_o at_o that_o distance_n and_o posture_n because_o the_o experiment_n thereby_o will_v be_v more_o sensible_o evident_a though_o it_o hold_v in_o any_o two_o object_n at_o whatever_o distance_n till_o the_o distance_n be_v so_o great_a that_o the_o interval_n between_o the_o two_o eye_n bear_v no_o sensible_a proportion_n thereto_o that_o be_v till_o the_o angle_n acb_n and_o much_o more_o a_o d_o b_o be_v so_o very_o small_a that_o the_o line_n ac_fw-la bc_n may_v be_v take_v to_o run_v as_o it_o be_v parallel_v this_o be_v declare_v i_o explicate_v the_o reason_n of_o this_o appearance_n as_o follow_v in_o the_o first_o case_n both_o eye_n be_v fix_v on_o c_o if_o the_o right_a eye_n b_o be_v shut_v the_o object_n d_o will_v appear_v to_o the_o left_a hand_n of_o c_o then_o shut_v the_o left_a eye_n a_o and_o open_v the_o right_a eye_n b_o and_o look_v at_o c_o d_o will_v appear_v to_o the_o right_a hand_n of_o c_o therefore_o open_v both_o a_o and_o b_o and_o look_v steadfast_o on_o c_o the_o object_n d_o will_v appear_v on_o both_o side_n c_o that_o be_v both_o to_o the_o right_n and_o left_a hand_n of_o c_o and_o therefore_o double_a and_o it_o be_v manifest_a the_o right_a eye_n b_o receive_v the_o right_a image_n of_o d_o and_o the_o left_a eye_n a_o the_o left_a image_n of_o d_o therefore_o in_o this_o case_n to_o the_o right_a eye_n be_v shut_v the_o right_a image_n of_o d_o disappear_v and_o to_o the_o left_a eye_n be_v shut_v the_o left_a image_n of_o d_o disappear_v but_o in_o the_o second_o case_n fix_v both_o eye_n on_o d_o c_o seem_v double_a for_o the_o left_a eye_n a_o be_v shut_v c_o appear_v to_o b_o on_o the_o left_a hand_n of_o d_o then_o the_o right_a eye_n be_v shut_v the_o left_a eye_n a_o see_v c_o on_o the_o right_a hand_n of_o d_o so_o that_o in_o this_o case_n the_o right_a eye_n receive_v the_o left_a image_n of_o c_o and_o the_o left_a eye_n the_o right_a image_n of_o c_o and_o consequent_o the_o open_n or_o shut_v of_o either_o do_v in_o this_o case_n make_v the_o contrary_a image_n of_o c_o disappear_z and_o why_o c_o shall_v seem_v double_a be_v plain_a in_o this_o case_n for_o the_o right_a eye_n see_v it_o on_o the_o left_a hand_n of_o d_o and_o the_o left_a eye_n on_o the_o right_a hand_n of_o d_o so_o that_o both_o eye_n see_v it_o on_o both_o hand_n of_o d_o and_o therefore_o double_a but_o then_o in_o the_o first_o case_n the_o object_n d_o and_o not_o the_o object_n c_o seem_v double_a and_o in_o the_o second_o case_n the_o object_n c_o and_o not_o the_o object_n d_o seem_v double_a for_o in_o vision_n there_o be_v a_o difference_n between_o look_v and_o see_v whatever_o object_n i_o look_v at_o with_o both_o eye_n appear_v single_a and_o all_o other_o more_o remote_a or_o nigh_o that_o i_o see_v appear_v double_a for_o upon_o the_o object_n i_o look_v at_o the_o optic_a axe_n do_v concur_v but_o not_o so_o on_o those_o i_o only_o see_v and_o this_o be_v the_o reason_n that_o at_o any_o time_n i_o can_v make_v all_o the_o object_n about_o i_o seem_v confuse_v only_o by_o turn_v the_o optic_a axe_n so_o that_o they_o may_v concur_v in_o the_o free_a air_n as_o if_o there_o be_v a_o certain_a visible_a object_n there_o before_o they_o though_o real_o there_o be_v none_o and_o that_o the_o concurrence_n of_o the_o axe_n optici_fw-la in_o a_o single_a point_n or_o object_n be_v sufficient_a to_o make_v that_o object_n seem_v but_o one_o beside_o the_o proof_n of_o the_o forego_n experiment_n i_o shall_v endeavour_v to_o evince_v or_o at_o least_o to_o explicate_v by_o a_o other_o know_v affection_n of_o vision_n the_o explanation_n whereof_o be_v allow_v by_o all_o man_n as_o satisfactory_a it_o be_v this_o in_o tab._n 41._o fig._n 2._o 4._o the_o image_n a_o b_o of_o the_o object_n a_o b_o be_v paint_v on_o the_o retina_fw-la invert_v and_o yet_o the_o eye_n or_o rather_o the_o soul_n by_o mean_n of_o the_o eye_n see_v the_o object_n erect_v and_o in_o its_o natural_a posture_n because_o the_o mind_n take_v no_o notice_n of_o what_o happen_v to_o the_o ray_n in_o the_o eye_n by_o refraction_n or_o decussation_n but_o in_o its_o direction_n towards_o the_o object_n it_o follow_v straight_o alongst_o the_o ray_n as_o they_o by_o their_o impulse_n and_o in_o their_o plain_a course_n lead_v it_o and_o consequent_o follow_v the_o ray_n a_o a_o it_o be_v direct_v straight_o to_o the_o upper_a part_n of_o the_o object_n and_o also_o follow_v the_o ray_n b_o b_o it_o be_v direct_v to_o the_o low_a part_n of_o the_o object_n and_o so_o of_o the_o rest_n for_o suppose_v the_o ball_n of_o the_o eye_n take_v out_o of_o its_o socket_n or_o cavity_n in_o the_o skull_n and_o a_o man_n receive_v in_o the_o socket_n a_o impulse_n by_o a_o stick_n come_v in_o the_o posture_n of_o b_o b_o and_o hit_v he_o on_o the_o upper_a part_n of_o the_o cavity_n sure_o he_o will_v never_o look_v for_o the_o original_a of_o this_o blow_n at_o a_o but_o will_v be_v certain_o direct_v to_o hunt_v back_o as_o it_o be_v alongst_o the_o stick_n b_o b_o towards_o the_o place_n from_o whence_o the_o stroke_n come_v so_o the_o mind_n do_v hunt_v back_o by_o mean_n of_o each_o pencil_n of_o ray_n which_o be_v as_o it_o be_v a_o stick_n give_v the_o retina_fw-la a_o certain_a impulse_n to_o the_o point_n from_o whence_o it_o come_v and_o be_v thereby_o direct_v straight_o thereto_o to_o apply_v this_o to_o what_o i_o intend_v i_o say_v then_o that_o the_o mind_n or_o visive_a faculty_n if_o i_o may_v have_v leave_n to_o use_v that_o word_n for_o a_o thing_n we_o all_o understand_v and_o can_v better_o express_v take_v no_o notice_n that_o there_o be_v two_o axe_n optici_fw-la or_o two_o picture_n make_v by_o those_o axe_n optici_fw-la on_o each_o retina_fw-la but_o follow_v back_o and_o hunt_v counter_a alongst_o these_o axe_n it_o be_v direct_v to_o and_o determine_v in_o one_o single_a point_n and_o therefore_o it_o see_v it_o as_o one_o and_o see_v this_o speculation_n do_v natural_o lead_v i_o to_o the_o consideration_n of_o a_o opinion_n first_o as_o i_o think_v start_v by_o the_o celebrate_v gassendus_fw-la and_o since_o embrace_v by_o many_o viz._n that_o we_o see_v but_o with_o one_o eye_n at_o once_o one_o and_o the_o same_o point_n of_o a_o object_n otiante_fw-la alio_fw-la as_o they_o term_v it_o whilst_o the_o other_o be_v idle_a and_o do_v nothing_o i_o shall_v not_o think_v it_o improper_a to_o subjoin_v to_o my_o former_a discourse_n something_o relate_v to_o that_o opinion_n confine_v myself_o only_o to_o what_o may_v something_o illustrate_v my_o former_a explanation_n for_o to_o enumerate_v all_o the_o experiment_n that_o prove_v we_o see_v with_o two_o eye_n will_v swell_v this_o far_o beyond_o the_o limit_n i_o design_v it_o therefore_o to_o the_o matter_n against_o our_o see_v with_o two_o eye_n at_o once_o one_o and_o the_o
same_o point_n of_o a_o object_n it_o be_v common_o object_v that_o if_o it_o be_v so_o every_o object_n will_v seem_v in_o two_o place_n at_o once_o vide_fw-la gassendi_n epist._n 4._o de_fw-la magnit_fw-la solis_fw-la humilis_fw-la &_o sublimis_fw-la &_o taqueti_n opt._n lib._n 1._o prop._n 2._o thus_o in_o tab._n 41._o fig._n 3._o 3._o if_o the_o eye_n a_o b_o look_v at_o the_o object_n c_o and_o both_o see_v it_o at_o a_o time_n a_o will_v see_v it_o on_o the_o opposite_a wall_n suppose_v at_o e_o and_o b_o at_z d._n i_o be_o so_o far_o from_o think_v this_o a_o objection_n that_o i_o assert_v first_o that_o we_o do_v see_v all_o object_n in_o two_o place_n and_o that_o this_o be_v not_o take_v notice_n of_o by_o we_o upon_o these_o account_n first_o the_o common_a object_n of_o our_o sight_n be_v large_a and_o the_o axe_n of_o our_o eye_n direct_v to_o but_o one_o physical_a point_n thereof_o at_o a_o time_n and_o then_o we_o can_v be_v expect_v to_o see_v such_o in_o two_o place_n at_o once_o for_o when_o i_o read_v on_o a_o flat_a broad_a book_n where_o be_v the_o opposite_a wall_n for_o a_o single_a small_a letter_n to_o be_v see_v on_o at_o two_o place_n the_o letter_n themselves_o be_v fix_v to_o the_o surface_n that_o determine_v the_o sight_n what_o i_o instance_n in_o letter_n on_o a_o book_n may_v be_v accommodate_v to_o most_o other_o object_n second_o there_o be_v few_o object_n dispose_v fit_o for_o show_v we_o that_o we_o see_v they_o in_o two_o place_n for_o either_o their_o bulk_n hinder_v the_o experiment_n from_o appear_v so_o plain_o or_o their_o distance_n from_o each_o other_o or_o from_o the_o eye_n three_o the_o wall_n de_fw-fr and_o the_o part_n thereof_o be_v see_v so_o confuse_o by_o the_o eye_n a_o b_o when_o fix_v on_o c_o that_o we_o can_v so_o clear_o observe_v this_o experiment_n and_o this_o happen_v to_o all_o object_n more_o remote_a or_o nigh_a to_o we_o than_o c_o when_o the_o eye_n be_v fix_v on_o c_o still_a suppose_v that_o itself_o be_v but_o in_o a_o moderate_a distance_n from_o we_o that_o be_v in_o such_o a_o distance_n from_o we_o as_o may_v bear_v some_o considerable_a proportion_n to_o the_o distance_n of_o the_o two_o eye_n from_o each_o other_o four_o the_o chief_a reason_n why_o we_o do_v not_o perceive_v so_o plain_o the_o object_n c_o to_o cover_z both_z d_o and_o e_z be_v because_o though_o d_o be_v cover_v by_o c_o from_o the_o eye_n b_o yet_o it_o be_v not_o cover_v from_o the_o eye_n a_o and_o therefore_o we_o think_v it_o not_o cover_v at_o all_o also_o though_o e_z be_v cover_v by_o c_o from_o the_o eye_n a_o yet_o it_o be_v not_o cover_v from_o the_o eye_n b_o and_o consequent_o because_o we_o see_v e_o though_o but_o with_o one_o eye_n b_o we_o imagine_v it_o not_o cover_v at_o all_o so_o that_o both_o the_o point_n d_o and_o e_o being_n open_v to_o both_o the_o eye_n a_o and_o b_o viz._n the_o point_n d_o to_o the_o eye_n a_o and_o the_o point_n e_o to_o the_o eye_n b_o we_o think_v neither_o of_o they_o cover_v whereas_o real_o they_o be_v both_o obscure_v each_o to_o its_o proper_a eye_n as_o will_v be_v evident_a by_o wink_v and_o from_o hence_o be_v manifest_v the_o falsity_n of_o taquet_n assertion_n in_o the_o forecited_a place_n viz._n that_o open_v both_o eye_n a_o and_o b_o fig._n 3._o and_o look_v at_o c_o it_o shall_v appear_v only_o to_o cover_v e_o he_o imagine_v that_o most_o man_n see_v general_o with_o their_o left_a eye_n whereas_o i_o say_v it_o shall_v appear_v to_o obscure_v neither_o e_z nor_o d_o though_o to_o each_o eye_n respective_o it_o cover_v each_o five_o whereas_o the_o bulk_n of_o object_n as_o i_o have_v note_v do_v hinder_v the_o experiment_n from_o be_v so_o sensible_o evident_a if_o by_o any_o experiment_n i_o can_v show_v how_o a_o large_a object_n may_v be_v double_v i_o think_v it_o will_v be_v sufficient_o plain_a therefore_o in_o tab._n 41._o fig._n 4._o 2._o let_v a_o b_o be_v the_o two_o eye_n before_o which_o at_o a_o convenient_a distance_n place_n the_o two_o candle_n c_o d_o then_o take_v a_o large_a piece_n of_o paper_n e_o f_o g_o h_n k_n in_o who_o middle_a at_o k_o there_o be_v a_o small_a hole_n this_o paper_n so_o place_n between_o the_o eye_n and_o candle_n that_o the_o eye_n a_o may_v through_o the_o hole_n k_o see_v the_o candle_n d_o and_o at_o the_o same_o time_n the_o eye_n b_o may_v see_v through_o the_o hole_n k_o the_o candle_n c_o the_o due_a distance_n of_o the_o paper_n that_o be_v requisite_a for_o this_o will_v be_v find_v by_o trial_n and_o wink_v alternate_o with_o the_o eye_n when_o all_o thing_n be_v in_o this_o posture_n open_v both_o eye_n a_o and_o b_o and_o direct_v they_o to_o look_v at_o either_o of_o the_o candle_n i_o say_v the_o hole_n k_o shall_v seem_v double_a and_o what_o be_v prove_v of_o the_o point_n k_o be_v true_a of_o all_o other_o point_n in_o the_o paper_n so_o the_o whole_a paper_n appear_v double_a but_o no_o point_n thereof_o be_v so_o evident_o double_v as_o the_o point_n k_o because_o they_o want_v the_o advantage_n of_o light_n behind_o they_o to_o render_v the_o experiment_n more_o sensible_a and_o upon_o this_o occasion_n i_o can_v but_o hint_n to_o all_o person_n that_o be_v desirous_a to_o make_v experiment_n about_o vision_n that_o they_o always_o employ_v the_o most_o luminous_a and_o vigorous_a object_n they_o can_v possible_o for_o many_o experiment_n will_v be_v evident_a by_o they_o that_o will_v not_o sensible_o succeed_v with_o other_o but_o i_o assert_v second_o that_o unless_o we_o see_v with_o both_o eye_n the_o two_o first_o mention_v experiment_n will_v not_o succeed_v and_o they_o may_v be_v reckon_v among_o the_o great_a argument_n that_o can_v be_v produce_v for_o it_o for_o suppose_v in_o fig._n 1._o a_o and_o b_o to_o look_v steadfast_o on_o c_o i_o say_v they_o see_v c_o in_o two_o place_n at_o once_o for_o they_o see_v it_o both_o on_o the_o right_a hand_n and_o left_a hand_n of_o d._n for_o it_o be_v the_o same_o thing_n to_o see_v c_o between_o two_o d_n as_o to_o see_v it_o at_o two_o place_n at_o once_o and_o this_o i_o will_v declare_v more_o full_o tab._n 41._o fig._n 5._o 5._o suppose_v the_o two_o eye_n a_o and_o b_o fix_v on_o the_o object_n c_o i_o say_v c_o appear_v on_o the_o opposite_a wall_n x_o z_o in_fw-la two_o place_n viz._n at_o e_o and_o f_o though_o neither_o e_z nor_o f_o be_v obscure_v thereby_o for_o the_o forego_n reason_n for_o let_v we_o suppose_v the_o object_n d_o of_o the_o first_o figure_n to_o be_v place_v due_o on_o this_o wall_n shut_v a_o the_o object_n c_o shall_v appear_v to_o b_o on_o the_o left_a hand_n of_o d_o by_o the_o angle_n d_o b_o e_o then_o shut_v b_o the_o object_n c_o shall_v appear_v to_o a_o on_o the_o right_a hand_n of_o d_o by_o the_o angle_n daf_n wherefore_o to_o both_o open_a at_o a_o time_n and_o look_v at_o it_o it_o shall_v appear_v on_o both_o side_n of_o d_o to_z a_o on_o the_o right_a side_n to_z b_o on_o the_o left_a side_n and_o this_o happen_v by_o double_v of_o d_o so_o that_o from_o hence_o this_o paradoxical_a corollary_n arise_v that_o a_o object_n may_v be_v see_v in_o two_o place_n and_o yet_o â—ot_n see_v double_a they_o that_o assert_v that_o we_o see_v but_o with_o one_o eye_n whilst_o the_o other_o be_v idle_a and_o do_v nothing_o assert_v likewise_o that_o all_o visual_a spirit_n recede_v from_o the_o idle_a eye_n and_o only_o supply_v the_o eye_n that_o see_v but_o i_o see_v no_o reason_n why_o the_o eye_n a_o b_o looking_z at_z c_o either_o of_o they_o shall_v be_v say_v destitute_a of_o spirit_n in_o respect_n of_o c_o which_o they_o see_v single_a and_o yet_o both_o replenish_v with_o spirit_n in_o respect_n of_o d_o which_o they_o see_v double_a the_o image_n of_o c_o and_o d_o both_o be_v paint_v on_o the_o retina_fw-la of_o a_o as_o well_o as_o of_o b_o and_o therefore_o a_o and_o b_o both_o be_v replenish_v with_o spirit_n to_o â—ee_z d_o even_o by_o the_o concession_n of_o our_o adversary_n why_o not_o to_o see_v c_o also_o at_o which_o they_o steadfast_o look_v appendix_n whilst_o this_o book_n be_v in_o the_o press_n my_o affair_n be_v such_o that_o i_o can_v not_o attend_v the_o perusal_n and_o correction_n thereof_o but_o therein_o have_v make_v use_n of_o my_o friend_n mr._n e._n halley_n who_o be_v willing_a to_o do_v i_o that_o service_n he_o after_o the_o first_o part_n hereof_o be_v finish_v send_v i_o a_o proposition_n of_o his_o own_o which_o i_o take_v to_o be_v of_o that_o
videbuntur_fw-la propinquissimè_fw-la &_o è_fw-la conuerso_fw-la sic_fw-la etiam_fw-la faceremus_fw-la solemn_a &_o lunam_fw-la &_o stellas_fw-la descendere_fw-la secundum_fw-la apparentiam_fw-la hic_fw-la inferius_fw-la etc._n etc._n thus_o in_o english_a great_a wonder_n than_o all_o these_o be_v perform_v by_o refracted_a vision_n for_o thereby_o it_o be_v easy_o make_v appear_v that_o the_o great_a object_n may_v be_v represent_v as_o very_o little_a and_o contrary_o and_o so_o likewise_o the_o most_o distant_a object_n as_o just_a at_o hand_n and_o contrary_o hereby_o also_o may_v we_o bring_v the_o sun_n and_o moon_n and_o star_n down_o here_o below_o in_o appearance_n etc._n etc._n this_o i_o think_v be_v so_o express_v in_o the_o point_n that_o it_o leave_v no_o room_n to_o doubt_v but_o that_o he_o have_v some_o admirable_a secret_n in_o optic_a glass_n add_v to_o this_o what_o he_o have_v in_o his_o epistle_n ad_fw-la parisiensem_fw-la of_o the_o secret_n of_o art_n and_o 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passage_n in_o his_o epistola_fw-la ad_fw-la parisiensem_fw-la cap._n 6._o a_o hundred_o year_n before_o barthold_n swartz_n live_v in_o omnem_fw-la distantiam_fw-la quam_fw-la volumus_fw-la possumus_fw-la artificialiter_fw-la componere_fw-la ignem_fw-la comburentem_fw-la ex_fw-la sale_n petrae_fw-la &_o aliis_fw-la these_o alia_fw-la in_o another_o manuscript_n copy_n be_v sulphur_n &_o carbonum_fw-la pulvis_fw-la and_o soon_o after_o he_o add_v praeter_fw-la haec_fw-la i._n e._n combustionem_fw-la sunt_fw-la alia_fw-la stupenda_fw-la naturae_fw-la nam_fw-la soni_fw-la velut_fw-la tonitrus_fw-la &_o coruscationes_fw-la possunt_fw-la fieri_fw-la in_o aere_fw-la imò_fw-la majore_fw-la horrore_fw-la quam_fw-la illa_fw-la quae_fw-la fiunt_fw-la per_fw-la naturam_fw-la nam_fw-la modica_fw-la materia_fw-la adapta_fw-la sc_n ad_fw-la quantitatem_fw-la unius_fw-la pollicis_fw-la sonum_fw-la facit_fw-la horribilem_fw-la &_o coruscationem_fw-la ostendit_fw-la violentem_fw-la &_o hoc_fw-la fit_a multis_fw-la modis_fw-la quibus_fw-la civitas_n aut_fw-la exercitus_fw-la destruatur_fw-la igne_fw-la exsiliente_fw-la cum_fw-la fragore_fw-la â—â—estimabili_fw-la mira_n haec_fw-la sint_fw-la si_fw-la quis_fw-la sciret_fw-la uti_fw-la in_fw-la debita_fw-la quantitate_fw-la &_o materia_fw-la by_o which_o last_o passage_n we_o may_v guess_v he_o have_v not_o the_o way_n of_o apply_v it_o to_o a_o gun_n though_o it_o be_v manifest_a he_o be_v sensible_a that_o some_o such_o use_n may_v be_v make_v of_o it_o but_o the_o particular_a manner_n do_v not_o offer_v itself_o to_o he_o at_o first_o i_o confess_v note_n i_o have_v not_o by_o i_o at_o this_o time_n the_o original_n from_o whence_o these_o passage_n be_v quote_v the_o present_a distraction_n of_o our_o miserable_a country_n have_v separate_v i_o and_o my_o book_n and_o the_o place_n where_o i_o be_o afford_v not_o the_o copy_n therefore_o if_o in_o these_o quotation_n i_o be_o any_o wise_a mistake_v i_o must_v not_o be_v blame_v acknowledge_v that_o i_o have_v they_o at_o second_o hand_n from_o the_o forename_a author_n but_o to_o return_v to_o our_o optick-glass_n it_o be_v evident_a that_o bacon_n be_v acquaint_v with_o they_o and_o probable_o know_v how_o to_o adapt_v they_o in_o a_o telescope_n but_o the_o long_a and_o close_a imprisonment_n he_o suffer_v before_o his_o death_n for_o it_o be_v say_v no_o one_o be_v permit_v to_o speak_v to_o he_o and_o that_o all_o his_o write_n book_n and_o instrument_n be_v seize_v and_o burn_v except_o only_o those_o few_o fragment_n of_o he_o which_o we_o have_v save_v accidental_o be_v the_o reason_n that_o we_o have_v no_o far_a advancement_n of_o his_o in_o this_o kind_n transmit_v to_o posterity_n but_o it_o be_v very_o probable_a that_o the_o use_n of_o single_a glass_n in_o spectacle_n as_o be_v a_o invention_n of_o immediate_a advantage_n to_o human_a life_n and_o in_o itself_o very_o easy_a and_o simple_a may_v therefore_o be_v present_o catch_v at_o by_o the_o 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instrument_n be_v that_o a_o dutchman_n have_v then_o late_o make_v one_o which_o set_v he_o galileo_n upon_o the_o thought_n how_o to_o effect_v it_o which_o he_o say_v he_o successful_o discover_v by_o the_o consideration_n of_o refraction_n and_o find_v that_o a_o concave_a and_o a_o convex_a glass_n right_o adapt_v will_v perform_v what_o he_o only_o hear_v in_o general_a of_o the_o dutch_a invention_n but_o certain_o the_o first_o public_a notice_n of_o this_o contrivance_n come_v from_o some_o of_o the_o forementioned_a dutchman_n for_o friar_n bacon_n hint_n mention_n not_o the_o particular_a combination_n of_o the_o glass_n and_o therefore_o the_o instrument_n be_v deserve_o call_v tubus_fw-la batavus_fw-la though_o we_o must_v confess_v at_o the_o same_o time_n that_o galileo_n an._n 1610._o see_v his_o nuâ—cius_fw-la sidereus_fw-la do_v first_o apply_v this_o curious_a instrument_n to_o celestial_a observation_n and_o have_v then_o make_v such_o wonderful_a discovery_n in_o the_o heaven_n thereby_o that_o all_o his_o philosophic_a successor_n have_v ever_o since_o attempt_v to_o climb_v high_o by_o lengthen_v their_o ladder_n and_o advance_v this_o instrument_n by_o many_o degree_n however_o i_o must_v not_o here_o conceal_v the_o pretence_n of_o baptista_n porta_n porta_n who_o in_o his_o magia_n
be_v observe_v in_o this_o planet_n be_v a_o spot_n first_o see_v by_o our_o ingenious_a mr._n hook_n may_v 9_o h._n 9_o p._n m._n 1665._o rotation_n by_o this_o spot_n it_o be_v manifest_a that_o jupiter_n turn_v round_o his_o own_o axis_n in_o the_o space_n of_o less_o than_o 10_o hour_n or_o about_o 9_o â—_o 56_o â—_o earth_n a_o very_a strong_a argument_n to_o prove_v that_o our_o earth_n may_v do_v so_o likewise_o since_o jupiter_n who_o be_v so_o considerable_o big_a than_o the_o earth_n have_v a_o motion_n much_o more_o quick_a than_o we_o in_o 24_o h._n kepler_n upon_o the_o restauration_n of_o the_o pythagorean_n or_o copernican_n hypothesis_n do_v conjecture_v from_o the_o motion_n of_o the_o primary_n planet_n about_o the_o sun_n as_o their_o centre_n that_o the_o sun_n move_v about_o its_o own_o axis_n but_o can_v not_o evince_v it_o till_o future_a observation_n by_o the_o telescope_n discover_v spot_n in_o the_o sun_n and_o by_o they_o demonstrate_v that_o the_o sun_n revolve_v on_o its_o own_o axis_n in_o 25_o ¼_n day_n jupiter_n have_v four_o secondary_a planet_n move_v round_o he_o and_o he_o himself_o in_o their_o centre_n turn_v on_o his_o axis_n our_o earth_n have_v a_o secundary_a planet_n the_o moon_n that_o move_v round_o she_o once_o a_o month_n be_v it_o not_o therefore_o high_o probable_a that_o the_o earth_n also_o revolve_v diurnal_o on_o its_o axis_n for_o a_o far_a account_n of_o this_o spot_n in_o jupiter_n i_o refer_v to_o the_o philosoph_n transact_v n._n 1._o p._n 3._o n._n 4._o p._n 75._o n._n 8._o p._n 143._o n._n 12._o p._n 209._o n._n 15._o p._n 246._o n._n 82._o p._n 4039._o 12._o eâ—tion_n but_o before_o i_o leave_v saturn_n and_o jupiter_n i_o can_v but_o take_v notice_n of_o one_o admirable_a property_n for_o the_o knowledge_n whereof_o we_o be_v behold_v to_o the_o telescope_n and_o that_o be_v the_o wonderful_a agreement_n which_o be_v find_v in_o all_o the_o several_a system_n of_o our_o vortex_n as_o well_o between_o 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mathematica_fw-la lib._n 3._o hypoth_o 5._o and_o the_o same_o law_n of_o motion_n be_v strict_o observe_v by_o the_o five_o primary_n planet_n and_o the_o earth_n about_o the_o sun_n as_o he_o note_n hypoth_o 7_o 8._o this_o be_v also_o verify_v by_o mons._n cassini_n in_o the_o five_o satellite_n of_o saturn_n as_o appear_v by_o his_o account_n of_o they_o in_o the_o philosoph_n transact_v num._n 92._o p._n 5178._o n._n 133._o p._n 831._o n._n 181._o p._n 79._o and_o from_o hence_o may_v we_o just_o fall_v into_o the_o deep_a admiration_n that_o one_o and_o the_o same_o law_n of_o motion_n shall_v be_v observe_v in_o body_n so_o vast_o distant_a from_o each_o other_o and_o which_o seem_v to_o have_v no_o dependence_n or_o correspondence_n with_o each_o other_o this_o do_v most_o evident_o demonstrate_v that_o they_o be_v all_o at_o first_o put_v into_o motion_n by_o one_o and_o the_o same_o unerring_a hand_n even_o the_o infinite_a power_n and_o wisdom_n of_o god_n who_o have_v fix_v this_o order_n among_o they_o all_o and_o have_v establish_v a_o law_n which_o they_o can_v transgress_v chance_n or_o dull_a matter_n can_v never_o produce_v such_o a_o harmonious_a regularity_n in_o the_o motion_n of_o body_n so_o vast_o distant_a this_o plain_o show_v a_o design_n and_o intention_n in_o the_o first_o mover_n and_o with_o submission_n to_o the_o reverend_n and_o learned_a divine_n i_o be_o apt_a to_o think_v that_o one_o argument_n draw_v from_o the_o order_n beauty_n and_o design_n of_o thing_n be_v more_o forecible_a against_o atheism_n than_o multitude_n of_o notional_a proof_n draw_v from_o idea_n apparition_n of_o spectre_n witch_n 〈◊〉_d etc._n etc._n not_o that_o these_o shall_v lose_v their_o due_a strength_n for_o beside_o the_o heaven_n even_o the_o little_a globe_n we_o inhabit_v afford_v we_o infinite_a variety_n in_o this_o kind_n and_o for_o my_o own_o part_n i_o must_v confess_v i_o can_v read_v more_o divinity_n in_o mr._n charlton_n admirable_a musaeum_fw-la on_o a_o box_n of_o beautiful_a shell_n of_o delicate_o paint_a plant_n curious_o adorn_v infect_v serpent_n bird_n or_o mineral_n than_o in_o large_a volume_n of_o notional_a writer_n for_o animal_n plant_n and_o mineral_n do_v yield_v we_o abundant_a instance_n which_o visible_o show_v a_o design_n or_o end_v propose_v which_o as_o it_o can_v possible_o consist_v with_o chance_n so_o neither_o can_v it_o be_v apprehend_v to_o have_v be_v so_o ab+aeterno_fw-la for_o it_o be_v absolute_o unconceivable_a that_o a_o thing_n design_v for_o some_o end_n or_o purpose_n shall_v not_o be_v so_o design_v in_o time_n by_o some_o design_v be_v but_o i_o beg_v pardon_n for_o this_o digression_n in_o which_o i_o be_o thus_o engage_v before_o i_o be_v aware_a to_o return_v therefore_o to_o our_o subject_n mars_n mars_n offer_v himself_o next_o who_o trust_v in_o his_o own_o strength_n be_v attend_v by_o no_o guard_n but_o the_o pry_v telescope_n discover_v in_o his_o face_n scar_n spot_n and_o ruggedness_n as_o we_o may_v find_v in_o the_o philosoph_n transact_v num._n 14._o p._n 239._o etc._n etc._n by_o these_o spot_n the_o acute_a cassini_n have_v determine_v rotation_n that_o he_o turn_v on_o his_o own_o axis_n once_o in_o 24_o h._n 40â—_n though_o other_o assign_v his_o revolution_n perform_v in_o just_a half_a that_o time_n a_o mistake_v easy_a enough_o vid._n ibidem_fw-la the_o fiery_a face_n of_o this_o planet_n require_v a_o very_a good_a telescope_n to_o view_v he_o and_o a_o small_a aperture_n on_o the_o object-glass_n or_o else_o this_o glare_a light_n make_v but_o a_o confuse_a appearance_n but_o however_o furious_a his_o beam_n be_v he_o be_v behold_v for_o they_o as_o all_o the_o rest_n of_o the_o planet_n to_o the_o great_a fountain_n of_o light_n and_o heat_v the_o sun_n for_o what_o the_o great_a distance_n of_o saturn_n and_o jupiter_n and_o their_o be_v so_o much_o above_o the_o sun_n as_o i_o may_v so_o speak_v hinder_v we_o from_o see_v decrease_v viz._n their_o increase_n and_o decrease_v in_o light_n like_o our_o moon_n be_v very_o visible_a in_o the_o planet_n mars_n who_o in_o his_o quadrature_n with_o the_o sun_n and_o in_o his_o perigeon_n may_v be_v see_v almost_o bissect_v but_o never_o corniculate_v or_o falcate_v as_o the_o other_o inferior_n vid._n hevelii_n selenograph_n cap._n 4._o p._n 66._o spot_n the_o glorious_a sun_n do_v next_o present_n in_o who_o bright_a face_n we_o can_v hardly_o expect_v to_o find_v dark_a spot_n yet_o such_o there_o be_v and_o frequent_v too_o scheinerus_n in_o his_o rosa_fw-la ursma_n have_v publish_v a_o large_a book_n in_o fol._n of_o nothing_o else_o and_o hevelius_n at_o the_o end_n of_o his_o selenography_n have_v many_o observation_n of_o these_o maculae_fw-la as_o also_o of_o some_o bright_a spot_n in_o the_o sun_n call_v faculae_fw-la the_o way_n of_o observe_v they_o be_v teach_v at_o large_a in_o the_o foresay_a author_n and_o be_v in_o short_a either_o by_o admit_v the_o light_n of_o the_o sun_n through_o a_o telescope_n upon_o a_o white_a paper_n in_o a_o dark_a room_n or_o by_o arm_v the_o eye_n with_o a_o small_a thin_a glass_n smoke_v over_o a_o torch_n lamp_n or_o candle_n and_o with_o it_o look_v through_o a_o telescope_n at_o the_o sun_n body_n rotation_n the_o only_a discovery_n that_o have_v be_v make_v by_o these_o maculae_fw-la be_v that_o the_o sun_n revolve_v round_o his_o own_o axis_n in_o the_o space_n of_o about_o 25_o ¼_n day_n but_o for_o a_o complete_a and_o succinct_a account_n of_o the_o theory_n of_o these_o maculae_fw-la and_o their_o motion_n i_o refer_v the_o reader_n to_o the_o excellent_a mathematician_n andrew_n tacquet_n astronom_n lib._n 8._o tract_n 3._o num._n 7._o it_o be_v only_a to_o be_v note_v that_o for_o these_o several_a year_n past_a the_o appearance_n of_o these_o maculae_fw-la have_v be_v much_o more_o