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more_o difficult_a and_o nice_a to_o lie_v upon_o any_o thing_n that_o decline_v from_o a_o level_n than_o quicksilver_n yet_o lie_v never_o so_o much_o of_o it_o upon_o this_o board_n while_o it_o be_v swing_v it_o shall_v lie_v dead_a and_o without_o motion_n but_o no_o soon_o you_o stop_v the_o motion_n of_o the_o wood_n but_o assoon_o the_o bullet_n or_o the_o quicksilver_n be_v hurl_v either_o this_o way_n or_o that_o way_n observaton_n xii_o i_o find_v it_o mention_v by_o some_o learned_a person_n that_o when_o a_o ship_n be_v under_o sail_n if_o a_o stone_n be_v demit_v from_o the_o top_n of_o the_o mast_n it_o will_v move_v down_o in_o a_o line_n parallel_n with_o it_o and_o fall_v at_o the_o root_n some_o may_v think_v it_o ought_v not_o to_o fall_v direct_o above_o the_o place_n it_o hang_v over_o but_o rather_o some_o distance_n behind_o see_v the_o ship_n have_v advance_v so_o much_o bound_n in_o the_o time_n wherein_o the_o stone_n be_v come_v down_o likewise_o while_o a_o 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throw_v a_o stone_n towards_o the_o brink_n of_o the_o water_n in_o this_o case_n he_o shall_v not_o hit_v the_o place_n he_o aim_v at_o but_o some_o other_o place_n more_o forward_o this_o let_v we_o see_v that_o when_o a_o gun_n be_v fire_v in_o a_o ship_n under_o sail_n the_o bullet_n can_v hit_v the_o place_n it_o be_v direct_v to_o neither_o can_v a_o man_n ride_v with_o a_o full_a career_n and_o shoot_v a_o pistol_n hit_v the_o person_n he_o aim_v at_o but_o must_v sure_o miss_v he_o notwithstanding_o that_o though_o in_o the_o very_a instant_n of_o time_n wherein_o he_o fire_v the_o mouth_n of_o the_o pistol_n be_v most_o just_o direct_v for_o remedy_v whereof_o allowance_n must_v be_v grant_v in_o the_o aim_v at_o the_o mark_n while_o a_o man_n throw_v up_o a_o stone_n in_o a_o ship_n under_o sail_n it_o must_v receive_v two_o distinct_a impulse_n one_o from_o the_o hand_n whereby_o it_o be_v carry_v upward_o the_o other_o from_o the_o ship_n whereby_o it_o be_v carry_v forward_o by_o this_o mean_n the_o stone_n in_o go_v up_o and_o come_v down_o can_v describe_v a_o perpendicular_a but_o a_o crooked_a line_n either_o a_o parabola_fw-la or_o a_o line_n very_o like_a unto_o it_o neither_o can_v it_o describe_v a_o perpendicular_a line_n in_o come_v down_o from_o the_o top_n of_o the_o mast_n though_o in_o appearance_n it_o seem_v to_o do_v so_o but_o a_o crooked_a one_o which_o in_o effect_n must_v be_v the_o half_a of_o that_o which_o it_o describe_v in_o go_v up_o and_o come_v down_o for_o this_o same_o cause_n a_o stone_n throw_v horizontal_o or_o towards_o the_o brink_n of_o the_o water_n must_v describe_v a_o crooked_a line_n also_o and_o a_o pistol_n bullet_n shot_n while_o a_o man_n be_v ride_v at_o a_o full_a career_n must_v describe_v a_o line_n of_o the_o same_o kind_n note_v that_o a_o man_n walk_v from_o the_o stern_a of_o a_o ship_n to_o the_o head_n walk_v a_o long_a way_n than_o in_o walk_v from_o the_o head_n to_o the_o stern_a second_o a_o man_n may_v walk_v from_o the_o head_n to_o the_o stern_a and_o yet_o not_o change_v his_o place_n it_o be_v observable_a that_o a_o man_n under_o board_n will_v not_o perceive_v whether_o the_o ship_n be_v sail_v or_o not_o and_o can_v know_v when_o her_o head_n go_v about_o and_o it_o be_v strange_a that_o when_o a_o man_n be_v enclose_v in_o a_o hogshead_n though_o he_o have_v light_a with_o he_o yet_o let_v he_o be_v never_o so_o oft_o whirl_v about_o he_o shall_v not_o know_v whether_o he_o be_v go_v about_o or_o not_o observation_n xiii_o i_o find_v in_o a_o philosophical_a transaction_n late_o print_v
80_o in_o the_o four_o and_o so_o forth_o until_o it_o become_v 1000_o he_o will_v find_v the_o great_a difficulty_n the_o long_o he_o pull_v it_o be_v just_a so_o with_o air_n or_o water_n raise_v mercury_n in_o a_o tub_n for_o as_o the_o cylinder_n of_o the_o mercury_n grow_v high_a by_o rise_v so_o it_o become_v heavy_a and_o consequent_o the_o imaginary_a surface_n upon_o which_o the_o base_a of_o the_o pillar_n rest_v be_v more_o and_o more_o burden_a and_o so_o become_v less_o and_o less_o able_a to_o press_v it_o up_o this_o lead_v we_o to_o a_o clear_a discovery_n of_o the_o reason_n why_o it_o be_v more_o difficult_a by_o suction_n to_o pull_v up_o mercury_n in_o a_o pipe_n than_o to_o pull_v up_o water_n and_o more_o hard_a to_o suck_v up_o ten_o foot_n of_o water_n then_o to_o suck_v up_o five_o for_o trial_n of_o this_o which_o be_v soon_o do_v take_v a_o slender_a glass-pipe_n 30_o or_o 40_o inch_n long_o open_a at_o both_o end_n and_o drown_v the_o one_o end_n among_o quicksilver_n and_o put_v your_o mouth_n to_o the_o other_o and_o have_v suck_v you_o will_v find_v great_a difficulty_n to_o pull_v up_o through_o the_o pipe_n 15_o inch_n of_o mercury_n than_o to_o pull_v up_o 10_o or_o 8_o and_o far_o great_a difficulty_n to_o suck_v up_o 20_o than_o to_o pull_v up_o 15._o it_o may_v be_v object_v that_o if_o a_o man_n have_v strength_n sufficient_a in_o his_o lung_n to_o suck_v out_o the_o whole_a air_n of_o the_o pipe_n thirty_o inch_n of_o mercury_n will_v come_v as_o easy_o up_o as_o three_z which_o seem_v to_o prove_v that_o the_o difficulty_n of_o the_o mercurie_n up-coming_a depend_v not_o upon_o the_o weakness_n of_o the_o air_n but_o upon_o the_o weakness_n of_o the_o lung_n and_o want_v of_o strength_n to_o suck_v i_o answer_v though_o a_o man_n be_v able_a to_o suck_v out_o the_o whole_a air_n of_o the_o pipe_n yet_o 30_o inch_n will_v never_o ascend_v so_o easy_o as_o ten_o nor_o ten_o so_o easy_o as_o three_o and_o that_o for_o the_o reason_n already_o give_v but_o why_o be_v it_o then_o say_v you_o that_o the_o strong_a the_o suction_n be_v the_o high_a the_o mercury_n ascend_v in_o the_o pipe_n i_o answer_v the_o suction_n serve_v for_o no_o use_n but_o to_o remove_v the_o impediment_n that_o hinder_v the_o mercury_n from_o come_v up_o which_o be_v nothing_o else_o but_o the_o air_n within_o the_o pipe_n now_o the_o more_o of_o this_o air_n that_o be_v take_v away_o by_o suction_n the_o strong_a the_o suction_n be_v the_o more_o air_n be_v take_v away_o the_o â—arder_n up_o come_v the_o mercury_n but_o why_o ought_v there_o to_o be_v difficulty_n in_o the_o suction_n of_o mercury_n to_o the_o altitude_n of_o 15_o or_o 20_o inch_n more_o than_o in_o the_o suction_n of_o water_n to_o that_o altitude_n i_o answer_v when_o i_o suck_v water_n up_o through_o a_o pipe_n the_o suction_n of_o the_o air_n above_o it_o be_v easy_a because_o the_o ascend_a water_n help_v much_o to_o drive_v it_o up_o to_o the_o mouth_n the_o outward_a air_n drive_v up_o both_o but_o the_o suction_n be_v difficult_a in_o mercury_n because_o the_o ascend_a liquor_n do_v not_o help_v so_o much_o to_o drive_v up_o the_o air_n to_o the_o mouth_n as_o the_o water_n do_v and_o the_o reason_n be_v because_o the_o air_n be_v more_o burden_v with_o 15_o inch_n of_o mercury_n than_o with_o 15_o inch_n of_o water_n can_v so_o easy_o drive_v up_o the_o one_o as_o the_o oâ—her_n and_o so_o mercury_n can_v so_o easy_o drive_v up_o the_o air_n of_o the_o pipe_n to_o the_o mouth_n as_o water_n do_v in_o a_o word_n according_a to_o the_o difference_n of_o specific_a weight_n between_o water_n and_o mercury_n so_o be_v the_o difficulty_n of_o suction_n therefore_o because_o mercury_n be_v 14_o time_n heavy_a than_o water_n there_o be_v 14_o time_n more_o difficulty_n to_o pull_v up_o the_o one_o than_o the_o other_o note_v that_o suction_n be_v not_o take_v here_o strict_o as_o contradistinguish_v from_o pulsion_n but_o in_o a_o large_a sense_n as_o it_o may_v comprehend_v it_o to_o proceed_v a_o little_a further_o let_v we_o suppose_v the_o pillar_n of_o mercury_n see_v the_o 11._o figure_n g_z h_n that_o be_v raise_v by_o the_o surface_n of_o air_n f_o g_o to_o be_v 29_o inch_n and_o every_o inch_n to_o weigh_v one_o ounce_n second_o that_o the_o say_a surface_n have_v 29_o degree_n of_o power_n or_o force_v in_o it_o for_o in_o all_o counterpoise_n the_o pondus_fw-la and_o the_o potentia_n be_v equal_a therefore_o if_o the_o mercury_n be_v 29_o inch_n the_o potentia_fw-la of_o the_o surface_n must_v have_v 29_o degree_n of_o strength_n or_o force_n in_o it_o to_o counterbalance_v the_o pondus_fw-la these_o thing_n be_v suppose_v which_o be_v evident_a let_v we_o imagine_v the_o surface_n of_o air_n to_o raise_v the_o mercury_n one_o inch_n above_o f_o g._n in_o this_o case_n the_o surface_n be_v weak_a than_o it_o be_v which_o i_o prove_v evident_o because_o it_o be_v now_o but_o able_a to_o raise_v 28_o of_o mercury_n imagine_v next_o the_o say_a surface_n to_o have_v raise_v the_o mercury_n two_o inch_n above_o f_o g_o than_o it_o follow_v that_o it_o must_v be_v yet_o weak_a because_o it_o be_v now_o but_o able_a to_o raise_v 27_o inch_n for_o by_o support_v two_o ounce_n of_o the_o pondus_fw-la it_o lose_v two_o degree_n of_o its_o own_o potentia_fw-la in_o raiâ—ing_v three_o inch_n of_o mercury_n it_o be_v three_o degree_n weak_a and_o in_o raise_v four_o it_o be_v four_o degree_n weak_a and_o so_o forth_o therefore_o have_v raise_v 28_o inch_n there_o be_v but_o one_o degree_n of_o force_n remain_v in_o the_o surface_n and_o when_o it_o have_v raise_v the_o whole_a namely_o 29_o it_o be_v no_o more_o able_a and_o can_v no_o more_o press_v for_o confirmation_n put_v the_o case_n that_o the_o surface_n of_o air_n f_o g_o be_v as_o able_a and_o have_v as_o much_o pressure_n in_o it_o after_o it_o have_v raise_v 29_o inch_n of_o mercury_n as_o it_o be_v after_o the_o raise_n of_o 10_o then_o it_o follow_v of_o necessity_n that_o after_o the_o raise_n of_o 20_o it_o shall_v raise_v 19_o more_o which_o be_v impossible_a see_v the_o great_a altitude_n be_v 29._o it_o follow_v of_o necessity_n i_o say_v because_o after_o the_o raise_n of_o 10_o it_o be_v able_a to_o raise_v 19_o more_o therefore_o if_o it_o be_v as_o able_a after_o 20_o as_o after_o 10_o it_o must_v raise_v 19_o after_o 20._o yea_o if_o it_o be_v as_o able_a after_o 20_o as_o 10_o it_o must_v be_v as_o able_a after_o 29_o as_o 10._o if_o this_o be_v than_o it_o may_v raise_v other_o 29_o and_o a_o three_o 29_o and_o so_o in_o infinitum_fw-la therefore_o i_o conclude_v that_o when_o two_o fluid_a body_n be_v in_o equilibrio_n one_o with_o another_o or_o when_o the_o pondus_fw-la be_v equal_a to_o the_o potentia_fw-la none_o of_o they_o do_v actual_o press_v upon_o another_o at_o least_o the_o surface_n have_v lose_v all_o its_o power_n and_o pressure_n which_o be_v also_o evident_a in_o the_o pillar_n for_o understand_v this_o let_v we_o suppose_v a_o c_o b_o figure_n 11._o to_o be_v a_o pipe_n 58_o inch_n long_o and_o full_a of_o mercury_n and_o every_o inch_n of_o it_o to_o weigh_v one_o ounce_n now_o when_o the_o orifice_n d_o be_v open_v there_o be_v here_o as_o great_a a_o inequality_n between_o the_o pondus_fw-la and_o the_o potentia_fw-la of_o the_o surface_n of_o air_n e_o b_o on_o which_o it_o rest_v as_o be_v between_o the_o surface_n f_o g_o and_o the_o pondus_fw-la of_o mercury_n h_n g._n for_o as_o f_o g_o have_v 29_o degree_n of_o power_n to_o raise_v g_o h_n so_o the_o pillar_n a_o b_o have_v 29_o ounce_n of_o weight_n to_o overcome_v the_o surface_n e_o b._n and_o as_o the_o surface_n f_o g_o become_v one_o degree_n weak_a by_o raise_v one_o inch_n of_o the_o mercury_n h_o g_o and_o two_o degree_n weak_a by_o raise_v two_o inch_n and_o so_o forward_o till_o it_o lose_v all_o its_o pressure_n so_o the_o pillar_n by_o fall_v down_o one_o inch_n lose_v one_o ounce_n of_o the_o weight_n by_o fall_v down_o two_o it_o lose_v two_o ounce_n and_o so_o forward_o till_o by_o fall_v down_o from_o a_o to_o c_o it_o lose_v all_o its_o weight_n and_o pressure_n but_o here_o occur_v a_o difficulty_n for_o if_o the_o surface_n f_o g_o have_v lose_v all_o its_o pressure_n by_o raise_v the_o mercury_n from_o g_o to_o h_n and_o if_o the_o pillar_n c_o b_o have_v lose_v all_o its_o pressure_n by_o fall_v down_o from_o a_o to_o c_o it_o follow_v that_o when_o a_o pillar_n of_o a_o fluid_a and_o a_o surface_n of_o a_o fluid_a be_v in_o equal_a term_n or_o bring_v to_o
pillar_n high_o without_o any_o alteration_n at_o least_o considerable_a in_o the_o weight_n for_o it_o still_o remain_v a_o foot_n of_o water_n whatever_o be_v the_o height_n of_o the_o pillar_n above_o it_o last_o the_o weight_n of_o a_o fluid_a be_v essential_a to_o it_o but_o the_o pressure_n be_v only_o accidental_a because_o it_o be_v only_o generate_v and_o beget_v in_o the_o inferior_a part_n by_o the_o weight_n of_o the_o superior_a which_o weight_n may_v be_v take_v away_o theorem_fw-la xxiii_o though_o the_o bensil_n of_o a_o fluid_a be_v not_o the_o same_o thing_n formal_o with_o the_o weight_n yet_o be_v they_o the_o same_o effective_o this_o proposition_n be_v true_a in_o order_n to_o many_o other_o thing_n beside_o fluids_n for_o we_o see_v that_o the_o sun_n and_o fire_n be_v formal_o different_a yet_o they_o may_v be_v the_o same_o effective_o because_o the_o same_o effect_n that_o be_v do_v by_o the_o heat_n of_o the_o sun_n may_v be_v do_v by_o the_o heat_n of_o the_o fire_n so_o the_o same_o effect_n that_o be_v produce_v by_o the_o weight_n of_o a_o fluid_a may_v be_v do_v by_o the_o pressure_n and_o bensill_n of_o it_o thus_o the_o mercurial_a cylinder_n in_o the_o torricellian_a experiment_n may_v be_v either_o sustain_v by_o the_o bensil_n of_o the_o air_n or_o the_o weight_n of_o it_o by_o the_o bensil_n as_o when_o no_o more_o air_n be_v admit_v to_o rest_n upon_o the_o stagnant_a mercury_n than_o three_o or_o four_o inch_n the_o rest_n be_v seclude_v by_o stop_v the_o orifice_n of_o the_o vessel_n by_o the_o weight_n of_o it_o as_o when_o a_o entire_a pillar_n of_o air_n from_o the_o top_n of_o the_o atmosphere_n rest_v upon_o the_o face_n of_o the_o stagnant_a quicksilver_n it_o be_v also_o evident_a in_o a_o clock_n which_o may_v be_v make_v to_o move_v either_o by_o a_o weight_n of_o lead_n or_o by_o the_o force_n and_o power_n of_o a_o steel_n spring_n theorem_fw-la xxiv_o the_o surface_n of_o water_n be_v able_a to_o sustain_v any_o weight_n whatsoever_o provide_v that_o weight_n press_v equal_o and_o uniform_o figure_n 1._o this_o be_v evident_a because_o the_o imaginary_a surface_n of_o water_n o_o t_o v_n x_o do_v real_o support_v the_o whole_a sixteen_o cube_n of_o water_n above_o it_o yea_o though_o they_o be_v sixteen_o thousand_o and_o the_o reason_n be_v because_o they_o press_v most_o equal_o and_o uniform_o what_o i_o affirm_v of_o the_o imaginary_a surface_n the_o same_o i_o affirm_v of_o the_o first_o and_o visible_a for_o let_v a_o plain_a body_n of_o lead_n never_o so_o heavy_a be_v lay_v upon_o the_o top_n of_o the_o water_n a_o b_o c_o d_o yet_o will_v it_o support_v it_o and_o keep_v it_o from_o sink_v provide_v it_o press_v uniform_o all_o the_o part_n of_o that_o surface_n it_o be_v clear_a also_o from_o the_o subsequent_a theorem_n theorem_fw-la xxv_o the_o surface_n of_o all_o water_n whatsoever_o support_v as_o much_o weight_n from_o the_o air_n as_o if_o they_o have_v the_o weight_n of_o thirty_o four_o foot_n of_o water_n above_o they_o or_o twenty_o nine_o inch_n of_o quicksilver_n press_v they_o this_o proposition_n be_v evident_a from_o this_o that_o the_o pressure_n of_o the_o air_n be_v able_a to_o raise_v above_o the_o surface_n of_o any_o water_n a_o pillar_n of_o water_n thirty_o four_o foot_n high_a for_o put_v the_o case_n there_o be_v a_o pump_n forty_o foot_n high_a erect_v among_o stagnant_a water_n and_o a_o sucker_n in_o it_o for_o extract_v the_o internal_a air_n a_o man_n will_v find_v that_o the_o water_n will_v climb_v up_o in_o it_o four_o and_o thirty_o foot_n which_o phenomenon_n can_v never_o happen_v unless_o the_o surface_n of_o the_o stagnant_a water_n among_o which_o the_o end_n of_o the_o pump_n be_v drown_v be_v as_o much_o press_v with_o the_o air_n as_o if_o it_o have_v a_o burden_n of_o water_n upon_o it_o thirty_o four_o foot_n high_a the_o second_o part_n be_v also_o evident_a because_o if_o a_o man_n drown_v the_o end_n of_o a_o long_a pipe_n in_o a_o vessel_n with_o stagnant_a quicksilver_n and_o remove_v the_o air_n that_o be_v within_o the_o pipe_n by_o a_o sucker_n or_o more_o easy_o by_o the_o help_n of_o the_o air-pump_n he_o will_v find_v the_o liquor_n to_o rise_v twenty_o nine_o inch_n above_o the_o surface_n below_o which_o thing_n can_v never_o come_v to_o pass_v unless_o the_o pressure_n of_o the_o air_n upon_o the_o surface_v of_o all_o body_n be_v equivalent_a to_o the_o pressure_n and_o weight_n of_o twenty_o nine_o inch_n of_o quicksilver_n theorem_fw-la xxvi_o all_o fluid_a body_n have_v a_o sphere_n of_o activity_n to_o which_o they_o be_v able_a to_o press_v up_o themselves_o or_o another_o fluid_a and_o no_o further_o which_o be_v less_o or_o more_o according_a to_o the_o altitude_n of_o the_o press_a fluid_n figure_n 2._o for_o understand_v this_o proposition_n let_v we_o imagine_v g_z h_o c_o d_o to_n be_v a_o vessel_n in_o who_o bottom_n there_o be_v five_o inch_n of_o mercury_n e_o f_o c_o d._n next_o that_o above_o the_o stagnant_a mercury_n there_o be_v thirty_o four_o foot_n of_o water_n rest_v namely_o a_o b_o e_o f._n last_o that_o upon_o the_o surface_n of_o the_o say_a water_n there_o be_v rest_v the_o element_n of_o air_n g_o h_o a_o b_o who_o top_n g_o h_n i_o reckon_v to_o be_v about_o six_o thousand_o fathom_n above_o a_o b._n beside_o these_o let_v we_o imagine_v that_o there_o be_v here_o three_o pipe_n open_a at_o both_o end_n the_o first_o whereof_o c_z a_o g_z have_v it_o be_v low_a orifice_n c_o drown_v among_o the_o stagnant_a mercury_n e_o f_o c_o d_o go_v so_o high_a that_o theu_o p_a orifice_n go_v above_o the_o top_n of_o the_o air_n g_o h._n the_o second_o who_o low_a orifice_n i_o be_v only_o drown_v among_o the_o water_n a_o b_o e_o f_o reach_v to_o the_o top_n of_o the_o air_n likewise_o the_o three_o who_o open_a end_n k_o be_v above_o the_o surface_n of_o the_o water_n a_o n_o b_o and_o hang_v in_o the_o open_a air_n go_v likewise_o above_o the_o atmosphere_n these_o thing_n be_v suppose_v we_o see_v that_o no_o fluid_n can_v by_o its_o own_o proper_a weight_n press_v any_o part_n of_o itself_o high_a than_o it_o be_v own_o surface_n see_v the_o stagnant_a mercury_n e_o f_o c_o d_o can_v press_v itself_o within_o the_o pipe_n c_o g_o high_o than_o e._n neither_o can_v the_o water_n a_o b_o e_o f_o press_v itself_o high_a within_o the_o pipe_n i_o l_o then_z the_o point_n n._n last_o neither_o can_v the_o air_n g_o h_o a_o b_o press_v itself_o within_o the_o pipe_n k_o m_o high_a than_o m._n but_o when_o one_o fluid_a press_v upon_o another_o as_o the_o water_n a_o b_o e_o f_o upon_o the_o mercury_n e_o f_o c_o d_o then_o do_v the_o say_a mercury_n ascend_v high_a than_o it_o be_v own_o surface_n namely_o from_o e_z to_z o_o which_o point_n be_v the_o high_a to_o which_o the_o thirty_o four_o foot_n of_o water_n a_o b_o e_o f_o can_v raise_v the_o mercury_n which_o altitude_n be_v twenty_o nine_o inch_n above_o the_o surface_n e_o i_o f._n but_o if_o a_o second_o fluid_fw-la be_v superad_v as_o the_o whole_a air_n g_o h_o a_o b_o then_o must_v the_o mercury_n according_a to_o that_o new_a pressure_n rise_v by_o proportion_n so_o rise_v the_o mercury_n from_o o_o to_o p_o other_o twenty_o nine_o inch_n by_o this_o same_o additional_a weight_n of_o air_n the_o water_n rise_v thirty_o four_o foot_n in_o the_o pipe_n i_o l_o namely_o from_o n_o to_o r._n now_o i_o say_v the_o outmost_a and_o high_a point_n to_o which_o the_o element_n of_o air_n g_o h_o a_o b_o can_v raise_v the_o mercury_n be_v from_o o_o to_o p_o for_o by_o the_o pressure_n of_o the_o water_n a_o b_o e_o f_o it_o rise_v from_o e_z to_z o._n and_o the_o high_a point_n to_o which_o the_o say_a air_n can_v raise_v the_o water_n be_v from_o n_o to_o r._n the_o reason_n of_o these_o determinate_a altitude_n must_v be_v seek_v for_o from_o the_o altitude_n of_o the_o incumb_a and_o press_v fluid_n for_o as_o these_o be_v less_o or_o more_o so_o be_v the_o altitude_n of_o the_o mercury_n and_o of_o the_o water_n within_o the_o pipe_n more_o or_o less_o the_o hight_v therefore_o of_o the_o mercury_n e_o o_fw-fr be_v twenty_o nine_o inch_n because_o the_o deepness_n of_o the_o press_a water_n a_o b_o e_o f_o be_v thirty_o four_o foot_n and_o the_o height_n of_o the_o water_n n_o r_o be_v thirty_o four_o foot_n because_o the_o height_n of_o the_o air_n g_o h_n above_o a_o b_o be_v six_o thousand_o fathom_n or_o thereabouts_o and_o for_o the_o same_o reason_n be_v the_o mercury_n o_o p_o twenty_o nine_o inch_n theorem_fw-la xxvii_o
m_o g_o h._n the_o same_o phenomenon_n happen_v in_o take_v the_o air_n out_o of_o the_o narrow_a pipe_n f_o k._n the_o reason_n be_v still_o unequal_a pressure_n for_o in_o remove_v the_o air_n that_o be_v within_o the_o pipe_n the_o part_n of_o the_o surface_n m_o and_o the_o part_n h_n remain_v burden_a while_o the_o part_n g_z be_v free_v of_o its_o burden_n therefore_o this_o part_n of_o the_o surface_n be_v liberate_v of_o its_o burden_n that_o come_v down_o through_o the_o pipe_n instant_o rise_v and_o climb_v up_o as_o far_o as_o the_o outward_a air_n rest_v upon_o m_n and_o h_n can_v raise_v it_o which_o be_v to_o e_o 34_o foot_n for_o the_o pressure_n of_o the_o air_n upon_o the_o surface_v of_o all_o water_n according_a to_o the_o 25_o theorem_fw-la be_v equivalent_a to_o the_o weight_n of_o 34_o foot_n of_o water_n must_v raise_v the_o say_a water_n in_o the_o pipe_n 34_o foot_n you_o do_v not_o wonder_v why_o it_o rise_v from_o i_o to_o g_o as_o in_o the_o first_o experiment_n no_o more_o ought_v you_o to_o wonder_n why_o it_o rise_v from_o g_z to_z e_z see_v the_o weight_n of_o the_o air_n do_v the_o same_o thing_n that_o 34_o foot_n of_o water_n rest_v upon_o the_o surface_n m_o h_n will_v do_v from_o this_o experiment_n we_o see_v first_o that_o the_o pressure_n of_o the_o air_n be_v the_o proper_a cause_n of_o the_o motion_n of_o water_n up_o through_o pump_n and_o siphons_n or_o any_o other_o instrument_n that_o be_v use_v in_o water-work_n of_o that_o kind_n for_o if_o the_o weight_n of_o the_o air_n rest_v upon_o the_o surface_n m_o h_n be_v the_o cause_n why_o the_o water_n climb_v up_o from_o g_z to_z e_z the_o same_o must_v be_v the_o cause_n why_o the_o stagnant_a water_n follow_v the_o sucker_n of_o the_o pump_n while_o it_o be_v pull_v up_o and_o the_o same_o be_v the_o cause_n why_o water_n ascend_v the_o leg_n of_o a_o siphon_n and_o be_v the_o cause_n why_o motion_n continue_v after_o suction_n be_v end_v we_o see_v second_o that_o every_o press_v fluid_a have_v a_o sphere_n of_o activity_n to_o which_o it_o be_v able_a to_o raise_v the_o fluid_a that_o be_v press_v this_o be_v evident_a in_o this_o experiment_n because_o the_o pressure_n of_o the_o air_n rest_v upon_o m_n h_n be_v able_a to_o raise_v the_o water_n the_o height_n of_o e_o in_o the_o wide_a pipe_n and_o the_o height_n of_o f_o in_o the_o narrow_a and_o no_o further_o even_o though_o the_o say_v pipe_n be_v far_o long_o and_o this_o altitude_n and_o high_a point_n be_v precise_o 34_o foot_n between_o air_n and_o water_n we_o see_v three_o that_o it_o be_v all_o one_o matter_n whether_o pump_n and_o siphons_n be_v wide_a or_o narrow_a whether_o the_o tub_n of_o the_o baroscope_n be_v wherein_o the_o mercury_n be_v suspend_v of_o a_o large_a diameter_n or_o of_o a_o lesser_a diameter_n this_o be_v also_o evident_a from_o the_o same_o experiment_n see_v there_o be_v no_o more_o difficulty_n in_o cause_v the_o water_n ascend_v the_o wide_a pipe_n than_o in_o cause_v it_o ascend_v the_o narrow_a one_o and_o the_o reason_n be_v because_o the_o press_a fluid_n repect_v not_o the_o press_v fluid_a according_a to_o its_o thickness_n and_o breadth_n but_o only_o according_a to_o its_o altitude_n therefore_o '_o be_v as_o easy_a for_o the_o air_n to_o press_v up_o water_n through_o a_o pump_n four_o foot_n in_o diameter_n as_o to_o press_v it_o up_o through_o a_o pump_n but_o one_o foot_n in_o diameter_n experiment_n iv._o figure_n 7._o this_o schematism_n represent_v a_o large_a vessel_n full_a of_o water_n who_o first_o and_o visible_a surface_n be_v d_o e_o h_o k._n the_o second_o that_o be_v imaginary_a be_v l_o i_o six_o foot_n below_o it_o the_o three_o of_o the_o same_o kind_n be_v m_n g_o six_o foot_n low_o the_o four_o be_v n_o f_o o_o six_o foot_n yet_o low_o the_o last_o and_o low_a be_v a_o b_o c._n there_o be_v here_o also_o four_o tub_n or_o rather_o one_o tub_n under_o four_o divers_a position_n with_o both_o end_n open_a after_o this_o tub_n d_o a_o be_v thrust_v below_o the_o water_n till_o it_o ascend_v as_o high_a as_o d_o in_o it_o lift_v it_o up_o between_o your_o finger_n till_o it_o have_v the_o position_n of_o the_o second_o pipe_n e_o f_o and_o then_o you_o shall_v see_v as_o the_o orifice_n of_o the_o pipe_n ascend_v the_o cylinder_n of_o water_n fall_v out_o by_o little_a and_o little_a until_o it_o be_v no_o long_o than_o e_o f._n again_o lift_v it_o further_o up_o till_o it_o have_v the_o position_n of_o the_o pipe_n h_o g_o then_o shall_v you_o find_v the_o cylinder_n of_o water_n become_v yet_o short_a last_o if_o it_o be_v situate_v as_o the_o pipe_n k_o i_o the_o internal_a water_n become_v no_o long_a than_o k_o i._o the_o reason_n of_o these_o phenomena_n be_v the_o same_o namely_o unequal_a pressure_n for_o the_o orifice_n a_o be_v lift_v up_o as_o high_a as_o f_o it_o come_v to_o the_o imaginary_a surface_n n_o o_o which_o be_v not_o under_o so_o much_o pressure_n as_o the_o other_o be_v therefore_o one_o part_n of_o it_o be_v more_o burden_v than_o another_o namely_o the_o part_n upon_o which_o the_o cylinder_n of_o water_n rest_v it_o present_o yield_v and_o suffer_v the_o cylinder_n to_o become_v short_a and_o light_a till_o it_o become_v no_o heavy_a than_o be_v proportionable_a to_o its_o own_o strength_n to_o make_v this_o reason_n more_o evident_a it_o be_v to_o be_v note_v that_o no_o surface_n of_o water_n be_v able_a to_o support_v a_o cylinder_n high_a than_o its_o own_o deepness_n that_o be_v to_o say_v if_o a_o surface_n be_v 40_o foot_n deep_a it_o be_v able_a to_o sustain_v a_o cylinder_n 40_o foot_n high_a and_o no_o more_o therefore_o the_o surface_n n_o o_o be_v but_o 18_o foot_n deep_a it_o can_v sustain_v a_o cylinder_n 24_o foot_n long_o for_o if_o that_o be_v than_o the_o potentia_n shall_v be_v inferior_a to_o the_o pondus_fw-la which_o be_v impossible_a in_o the_o hydrostaticks_n in_o effect_n it_o be_v no_o less_o absurdity_n then_o to_o say_v 18_o ounce_n be_v able_a to_o counterbalance_v 24._o for_o a_o second_o trial_n lift_v up_o the_o same_o pipe_n high_o till_o it_o acquire_v the_o position_n of_o the_o tub_n g_o h_n in_o this_o case_n the_o cylinder_n of_o water_n within_o it_o become_v yet_o short_a even_o no_o long_o than_z g_z h._n the_o reason_n be_v the_o same_o namely_o unequal_a pressure_n for_o when_o a_o cylinder_n of_o water_n 18_o foot_n high_a come_v to_o rest_v upon_o this_o surface_n that_o be_v but_o 12_o foot_n deep_a it_o make_v one_o part_n of_o it_o more_o burden_v than_o another_o therefore_o the_o part_n that_o be_v more_o press_v present_o yield_v and_o suffer_v the_o cylinder_n to_o fall_v down_o till_o the_o pondus_fw-la of_o it_o become_v equal_a to_o its_o own_o potentia_fw-la for_o the_o last_o trial_n lift_v up_o the_o tub_n till_o it_o acquire_v the_o position_n of_o the_o pipe_n k_o i_o in_o this_o case_n the_o water_n within_o it_o become_v no_o long_o than_o k_o i_o the_o surface_n l_o i_o that_o be_v but_o six_o foot_n deep_a not_o be_v able_a to_o sustain_v a_o cylinder_n 12_o foot_n high_a from_o this_o experiment_n we_o see_v first_o that_o in_o all_o fluid_a body_n there_o be_v a_o pressure_n which_o be_v more_o or_o less_o according_a to_o the_o deepness_n of_o that_o fluid_a this_o be_v evident_a from_o the_o four_o several_a surface_n there_o be_v more_o pressure_n and_o force_n in_o the_o low_a a_o b_o c_o then_z in_o the_o next_z n_o o_o and_o more_o in_o this_o then_o in_o the_o surface_n m_o g_o and_o more_o in_o this_o then_o in_o l_o 1_n we_o see_v second_o that_o in_o all_o fluid_n there_o be_v a_o pondus_fw-la and_o a_o potentia_n which_o two_o be_v always_o of_o equal_a force_n and_o strength_n the_o potentia_n be_v clear_a and_o evident_a in_o the_o surface_n by_o support_v the_o pillar_n which_o pillar_n be_v nothing_o else_o but_o the_o pondus_fw-la support_v and_o that_o they_o be_v always_o of_o equal_a strength_n be_v most_o evident_a also_o for_o when_o you_o endeavour_v to_o make_v the_o pondus_fw-la unequal_a to_o the_o potentia_n in_o make_v a_o surface_n 18_o foot_n deep_a to_o support_v a_o pillar_n 24_o foot_n high_a they_o of_o their_o own_o accord_n become_v equal_a the_o pillar_n become_v short_a and_o suitable_a to_o the_o strength_n of_o the_o surface_n that_o sustain_v it_o we_o see_v three_o that_o it_o be_v impossible_a for_o one_o part_n of_o the_o same_o horizontal_n surface_n to_o be_v more_o burden_v than_o another_o for_o when_o you_o endeavour_v to_o do_v it_o by_o set_v a_o long_a pillar_n upon_o it_o the_o part_n burden_v
instant_o yield_v till_o it_o be_v no_o more_o press_v than_o the_o next_o part_n to_o it_o we_o see_v four_a that_o the_o inequality_n that_o be_v between_o the_o pondus_fw-la and_o the_o potentia_fw-la in_o fluids_n be_v the_o proper_a cause_n of_o the_o motion_n of_o fluids_n for_o when_o you_o endeavour_v to_o make_v a_o surface_n 30_o foot_n deep_a sustain_v a_o pillar_n 40_o foot_n high_a this_o inequality_n be_v the_o true_a cause_n why_o the_o pillar_n subside_v and_o fall_v down_o and_o why_o the_o surface_n yield_v and_o give_v way_n to_o it_o and_o this_o inequality_n be_v the_o true_a cause_n why_o the_o motion_n of_o water_n through_o siphons_n continue_v for_o understand_v this_o you_o must_v conceive_v a_o siphon_n to_o be_v nothing_o else_o but_o a_o crooked_a pipe_n with_o two_o leg_n the_o one_o drown_v among_o water_n the_o other_o hang_v in_o the_o open_a air._n the_o use_n of_o it_o be_v for_o convey_v wine_n or_o water_n from_o one_o vessel_n to_o another_o which_o be_v easy_o do_v by_o suction_n now_o after_o suction_n be_v end_v the_o motion_n of_o the_o water_n continue_v till_o the_o surface_n become_v low_a than_o the_o orifice_n out_o of_o which_o it_o run_v the_o true_a reason_n then_o why_o the_o water_n flow_v out_o be_v the_o inequality_n between_o the_o potentia_fw-la of_o the_o air_n and_o the_o pondus_fw-la of_o the_o water_n the_o pondus_fw-la be_v strong_a than_o the_o potentia_fw-la for_o in_o air_n as_o in_o water_n we_o must_v conceive_v horizontal_n surface_v and_o these_o surface_n to_o be_v endow_v with_o pressure_n and_o force_n as_o be_v the_o surface_v of_o water_n now_o when_o the_o leg_n of_o a_o siphon_n be_v hang_v in_o the_o air_n it_o must_v rest_v upon_o one_o surface_n or_o another_o and_o consequent_o the_o water_n in_o it_o must_v rest_v upon_o the_o same_o surface_n if_o the_o potentia_fw-la of_o the_o surface_n be_v strong_a than_o the_o pondus_fw-la of_o the_o water_n the_o water_n be_v drive_v backward_o which_o always_o come_v to_o pass_v when_o the_o orifice_n be_v high_a than_o the_o surface_n of_o the_o water_n of_o the_o vessel_n among_o which_o the_o other_o leg_n be_v drown_v if_o the_o potentia_fw-la of_o the_o surface_n of_o that_o air_n be_v of_o equal_a power_n and_o strength_n with_o the_o pondus_fw-la of_o the_o water_n the_o water_n go_v neither_o backward_a nor_o forward_o but_o stand_v in_o equilibrio_n this_o happen_v when_o the_o orifice_n be_v neither_o high_o nor_o low_o than_o the_o surface_n of_o the_o water_n in_o the_o vessel_n but_o if_o the_o potentia_fw-la of_o the_o surface_n of_o the_o air_n be_v weak_a than_o the_o pondus_fw-la of_o the_o water_n in_o this_o case_n the_o air_n yield_v and_o suffer_v the_o water_n to_o run_v out_o even_o as_o a_o surface_n 30_o foot_n deep_a yield_v to_o a_o pillar_n of_o water_n 40_o foot_n high_a the_o same_o inequality_n be_v the_o reason_n why_o water_n climb_v up_o the_o pump_n why_o water_n climb_v up_o a_o pipe_n when_o a_o man_n suck_v with_o his_o mouth_n before_o suction_n the_o potentia_n that_o be_v in_o the_o surface_n of_o water_n among_o which_o the_o end_n of_o the_o pipe_n be_v drown_v be_v of_o equal_a force_n with_o the_o pondus_fw-la of_o the_o pillar_n of_o air_n that_o come_v down_o through_o the_o pipe_n or_o pump_n but_o assoon_o as_o a_o man_n begin_v to_o suck_v the_o say_a pillar_n of_o air_n become_v light_a and_o the_o water_n find_v this_o present_o ascend_v the_o same_o be_v the_o reason_n why_o the_o mercury_n fall_v down_o to_o 29_o inch_n in_o the_o baroscope_n and_o no_o further_o for_o as_o long_o as_o the_o pondus_fw-la of_o the_o pillar_n of_o mercury_n exceed_v the_o potentia_fw-la of_o the_o surface_n of_o air_n so_o long_o do_v the_o motion_n continue_v and_o when_o both_o be_v become_v equal_a in_o force_n the_o motion_n cease_v when_o the_o glass-tub_n be_v 40_o inch_n long_o and_o fill_v with_o mercury_n and_o invert_v after_o the_o common_a manner_n you_o be_v endeavour_v as_o it_o be_v to_o cause_v a_o surface_n 29_o inch_n deep_a sustain_v a_o pillar_n 40_o inch_n high_a which_o be_v utter_o impossible_a in_o fluids_n it_o be_v judge_v by_o many_o a_o wonder_n to_o see_v the_o deflux_n of_o the_o mercury_n in_o the_o baroscope_n but_o in_o effect_n there_o be_v no_o more_o cause_n of_o admiration_n in_o it_o than_o to_o see_v the_o cylinder_n of_o water_n grow_v short_a by_o lift_v the_o pipe_n up_o from_o one_o surface_n to_o another_o from_o this_o experiment_n we_o see_v the_o true_a reason_n why_o the_o mercurial_a cylinder_n of_o the_o baroscope_n become_v short_a and_o short_a according_a as_o a_o man_n climb_v up_o a_o mountain_n with_o it_o for_o at_o the_o root_n of_o the_o hill_n the_o surface_n of_o air_n that_o sustain_v the_o pillar_n of_o mercury_n be_v of_o great_a force_n than_o the_o surface_n at_o the_o middle_a part_n and_o this_o be_v strong_a than_o any_o surface_n at_o the_o top_n the_o pipe_n therefore_o be_v carry_v up_o from_o one_o surface_n to_o another_o the_o mercury_n in_o it_o must_v subside_o and_o fall_v down_o even_o as_o the_o water_n fall_v down_o and_o become_v short_a by_o lift_v the_o pipe_n from_o the_o surface_n a_o b_o c_o d_o to_o the_o surface_n n_o o._n and_o as_o the_o whole_a water_n will_v fall_v down_o if_o the_o orifice_n i_o be_v lift_v above_o the_o surface_n d_o e_o h_o k_o so_o if_o the_o baroscope_n can_v be_v carry_v so_o high_a till_o it_o come_v above_o the_o top_n of_o the_o air_n the_o whole_a mercurial_a cylinder_n will_v sure_o fall_v down_o and_o as_o by_o thrust_v down_o the_o say_a pipe_n to_o the_o bottom_n of_o the_o vessel_n again_o as_o the_o pipe_n d_o a_o the_o water_n ascend_v in_o it_o so_o by_o bring_v down_o the_o baroscope_n to_o the_o earth_n again_o the_o whole_a 19_o inch_n will_v rise_v again_o experiment_n v._o figure_n 8._o fill_v the_o vessel_n a_o d_o g_o h_o with_o water_n to_o the_o brim_n next_o thrust_v down_o the_o open_a orifice_n of_o the_o tub_n d_o a_o to_o the_o bottom_n and_o you_o shall_v see_v the_o water_n ascend_v in_o it_o as_o high_z as_o d_o according_a to_o the_o first_o experiment_n when_o this_o be_v do_v recline_v the_o say_a pipe_n till_o it_o lie_v as_o b_o e_z and_o you_o shall_v find_v the_o pipe_n complete_o full_a of_o water_n next_o erect_v the_o same_o tub_n again_o as_o d_o a_o and_o you_o shall_v see_v the_o cylinder_n of_o water_n fall_v down_o and_o become_v short_a as_o at_o first_o for_o salve_v this_o phenomenon_n and_o such_o like_a i_o must_v suppose_v this_o water_n to_o be_v 50_o inch_n deep_a and_o the_o tub_n i_o a_o and_o b_o e_z 90_o inch_n long_o and_o the_o say_a tub_n in_o recline_v to_o describe_v the_o quadrant_a of_o a_o circle_n f_o e_o g._n now_o the_o question_n be_v why_o there_o be_v but_o 50_o inch_n of_o water_n in_o the_o tub_n while_o erect_v there_o shall_v be_v 60_o in_o it_o when_o it_o be_v recline_v second_o why_o there_o shall_v be_v 90_o inch_n of_o water_n in_o the_o tub_n b_o e_o and_o but_o 50_o in_o it_o when_o it_o stand_v perpendicular_a as_o d_o a_o if_o you_o reply_v because_o there_o be_v 90_o inch_n in_o recta_fw-la linea_fw-la between_o the_o point_n b_o and_o the_o point_n e_o and_o but_o 50_o between_o a_o and_o d._n but_o this_o will_v not_o answer_v the_o case_n because_o if_o you_o stop_v the_o orifice_n e_o with_o the_o pulp_n of_o your_o finger_n before_o it_o be_v erect_v you_o will_v find_v the_o tub_n remain_v full_a of_o water_n even_o while_o it_o stand_v perpendicular_a and_o fall_v down_o when_o the_o orifice_n be_v open_v or_o while_o the_o tub_n stand_v perpendicular_a stop_v the_o orifice_n i_o and_o recline_v it_o as_o b_o e_z yet_o no_o more_o water_n will_v be_v find_v in_o it_o than_o 50_o inch_n but_o by_o unstop_v the_o say_a orifice_n the_o water_n climb_v up_o from_o r_z to_z e_z and_o become_v 90_o inch_n now_o what_o be_v the_o reason_n why_o it_o run_v up_o from_o r_z to_z e_z and_o why_o it_o fall_v down_o from_o i_o to_o d_o i_o answer_v then_o the_o water_n must_v run-up_v from_o r_z to_z e_z because_o of_o the_o inequality_n that_o be_v between_o the_o pondus_fw-la of_o the_o cylinder_n b_o r_o and_o the_o potentia_fw-la of_o the_o surface_n of_o water_n a_o b_o c_o that_o support_v the_o say_v cylinder_n for_o understand_v this_o know_v while_o the_o tub_n be_v erect_v there_o be_v a_o perfect_a equality_n between_o the_o weight_n of_o the_o pillar_n a_o d_o and_o the_o force_n or_o power_n of_o the_o surface_n that_o sustain_v it_o see_v a_o surface_n 50_o inch_n deep_a support_v a_o pillar_n 50_o inch_n
six_o inch_n thick_a but_o this_o seem_v rather_o to_o flow_v from_o the_o disproportion_n of_o magnitude_n see_v a_o circular_a plain_a 4_o inch_n in_o diameter_n can_v receive_v a_o base_a of_o a_o pillar_n 6_o inch_n in_o diameter_n but_o this_o be_v certain_a from_o the_o very_a nature_n of_o fluids_n that_o in_o a_o deep_a water_n wherein_o may_v be_v distinguish_v 100_o or_o 1000_o different_a surface_n each_o one_o be_v able_a to_o support_v his_o own_o burden_n and_o no_o more_o experiment_n xiii_o figure_n 17_o 18_o 19_o for_o make_v this_o experiment_n take_v two_o plain_a body_n of_o brass_n or_o marble_n well_o polish_v make_v they_o of_o any_o quantity_n but_o for_o this_o present_a use_n let_v each_o of_o they_o be_v four_o inch_n broad_a square-wise_a upon_o the_o back_n part_n let_v each_o one_o have_v a_o handle_n about_o six_o inch_n long_o of_o the_o same_o metal_n form_v with_o the_o plain_n itself_o in_o the_o sound_n if_o they_o be_v of_o brass_n as_o be_v represent_v in_o this_o schematism_n when_o they_o be_v thus_o prepare_v anoint_v their_o inner-side_n with_o oil_n or_o water_n and_o have_v thrust_v the_o one_o face_n alongst_o upon_o the_o other_o with_o all_o the_o strength_n you_o have_v till_o all_o the_o four_o edge_n agree_v two_o whereof_o be_v represent_v by_o a_o b_o and_o c_o d_o you_o will_v find_v they_o cleave_v so_o close_o together_o as_o if_o they_o be_v but_o one_o body_n the_o effect_n be_v this_o that_o ordinary_a strength_n will_v not_o pull_v they_o asunder_o and_o that_o under_o a_o surface_n of_o water_n a_o strong_a pull_n be_v require_v than_o in_o the_o air._n that_o we_o may_v deduce_v some_o hydrostatical_a conclusion_n from_o this_o experiment_n let_v we_o suppose_v these_o two_o plain_a body_n to_o be_v unite_v in_o the_o middle_n of_o the_o water_n i_o k_n p_o qui_fw-fr that_o be_v 34_o foot_n deep_a and_o suspend_v by_o a_o beam_n or_o long_a tree_n t_o v_n exist_v in_o the_o air_n near_o the_o top_n of_o the_o water_n by_o a_o chord_n s_o e_z pass_v between_o the_o middle_n of_o the_o beam_n and_o the_o end_n of_o the_o handle_n at_o e._n suppose_v next_o a_o great_a weight_n of_o lead_n r_o 350_o pound_n to_o be_v append_v to_o the_o end_n of_o the_o handle_n at_o h_n of_o the_o under_o plain_a body_n c_o d_o n_o o._n this_o do_v i_o affirm_v that_o the_o beam_n t_o v_n neither_o sustain_v the_o under_o plain_a body_n c_o d_o n_o o_o g_o h_n not_o the_o 350_o pound_n weight_n of_o lead_n r_o that_o hang_v down_o from_o the_o handle_n g_o h._n if_o it_o be_v object_v that_o the_o beam_n support_v the_o upper_a plain_a body_n a_o b_o l_o m_o f_o e_o therefore_o it_o must_v bear_v the_o weight_n also_o of_o the_o under_o plain_a c_o d_o n_o o_o g_o h_n with_o the_o weight_n r_o see_v they_o be_v both_o unite_v together_o and_o cleave_v so_o close_o as_o if_o they_o be_v but_o one_o body_n i_o answer_v it_o support_v the_o one_o unquestionable_o but_o not_o the_o other_o to_o explicate_v this_o hydrostatical_a mystery_n i_o must_v aver_v three_o thing_n first_o that_o the_o inferior_a plain_n be_v support_v by_o the_o upward_a pressure_n 〈◊〉_d the_o low_a water_n p_o q_o n_o o._n second_o that_o the_o burden_n which_o the_o beam_n sustain_v be_v not_o the_o weight_n of_o the_o under_o plain_a but_o the_o weight_n of_o the_o 34_o foot_n of_o water_n i_o k_o l_o m._n three_o that_o this_o weight_n be_v exact_o the_o weight_n of_o the_o inferior_a plain_n and_o lead_v r._n but_o be_v it_o not_o more_o easy_a to_o say_v that_o the_o beam_n support_v both_o the_o plain_n i_o answer_v if_o i_o say_v so_o i_o can_v neither_o affirm_v truth_n nor_o speak_v consequential_o but_o may_v it_o not_o be_v say_v that_o the_o inferior_a plain_n be_v support_v both_o by_o the_o beam_n and_o the_o low_a water_n p_o q_o n_o o?_o i_o answer_v this_o be_v impossible_a because_o one_o and_o the_o same_o weight_n can_v be_v support_v total_o by_o two_o distinct_a supporter_n for_o make_v these_o assertion_n evident_a i_o must_v suppose_v the_o superior_a water_n i_o k_o l_o m_o to_n be_v 34_o foot_n deep_a and_o to_o weigh_v if_o it_o be_v put_v into_o a_o balance_n 400_o pound_n and_o which_o be_v unquestionable_a that_o the_o say_a water_n rest_v upon_o the_o back_n of_o the_o superior_a plain_n l_o m._n i_o suppose_v second_o that_o the_o low_a water_n p_o q_o n_o o_o weigh_v as_o much_o and_o thrust_v up_o the_o inferior_a plain_n with_o as_o great_a weight_n as_o the_o superior_a plain_n be_v press_v down_o with_o by_o the_o superior_a water_n this_o be_v evident_a from_o former_a experiment_n and_o last_o i_o suppose_v each_o plain_n to_o weigh_v two_o pound_n and_o the_o weight_n of_o lead_n r_o 350._o it_o be_v to_o be_v observe_v here_o that_o no_o mistake_n may_v arise_v in_o the_o calculation_n afterward_o that_o though_o it_o be_v say_v this_o 34_o foot_n of_o water_n weigh_v 400_o pound_n yet_o in_o itself_o it_o weigh_v but_o 200_o but_o consider_v the_o pressure_n of_o the_o air_n upon_o i_o k_o which_o be_v as_o much_o it_o may_v be_v true_o say_v to_o weigh_v 400._o these_o thing_n be_v premit_v i_o say_v the_o weight_n that_o the_o beam_n t_o v_n sustain_v be_v not_o the_o weight_n of_o the_o inferior_a plain_n and_o the_o lead_n r_o but_o 352_o pound_n of_o the_o superior_a water_n i_o k_o l_o m_o and_o consequent_o that_o the_o inferior_a plain_n be_v support_v by_o the_o low_a water_n p_o q_o n_o o._n the_o reason_n be_v because_o the_o low_a water_n press_v up_o â—â—th_o the_o weight_n of_o 48_o pound_n it_o be_v in_o itself_o 400_o pound_n but_o be_v burden_v with_o 352_o it_o can_v thrust_v up_o with_o more_o weight_n than_o 48._o now_o it_o press_v up_o with_o 48_o must_v ease_v the_o beam_n of_o 48_o and_o counterpoise_v so_o much_o of_o the_o superior_a water_n and_o consequent_o the_o beam_n must_v support_v only_o 352_o pound_n of_o it_o but_o put_v the_o case_n you_o say_v the_o weight_n r_o be_v 130_o pound_n 160_o pound_n or_o 180_o pound_n will_v the_o beam_n be_v less_o or_o more_o burden_a with_o the_o superior_a water_n i_o answer_v if_o r_o be_v 130_o pound_n than_o the_o beam_n support_v only_o 132_o pound_n of_o the_o superior_a water_n for_o if_o the_o inferior_a be_v only_o burden_v with_o 130_o the_o weight_n of_o r_o and_o with_o two_o the_o weight_n of_o the_o inferior_a plain_n then_o must_v it_o press_v up_o with_o 368_o and_o by_o this_o mean_n must_v ease_v the_o beam_n of_o so_o much_o it_o sustain_v 132_o pound_n only_o according_a to_o this_o count_a when_o the_o lead_n r_o weigh_v 160_o pound_n the_o beam_n support_v only_o 238_o pound_n of_o the_o superior_a water_n if_o it_o weigh_v 180_o pound_n it_o sustain_v 218._o and_o if_o the_o weight_n r_o be_v take_v away_o the_o beam_n support_v no_o more_o of_o the_o superior_a water_n than_o two_o pound_n to_o proceed_v a_o little_a further_o imagine_v the_o two_o plain_n to_o be_v draw_v up_o 17_o foot_n near_o the_o first_o surface_n i_o k_o namely_o as_o high_a as_o z_o w._n this_o do_v the_o union_n break_v up_o and_o they_o present_o fall_v asunder_o the_o reason_n be_v because_o the_o surface_n z_o w_n be_v not_o able_a to_o support_v 352_o pound_n but_o only_o 300_o which_o i_o prove_v thus_o if_o 68_o foot_n sustain_v 400_o than_o 51_o foot_n must_v sustain_v 300._o i_o say_v 68_o and_o not_o 34_o because_o as_o be_v note_v the_o pressure_n of_o the_o air_n upon_o the_o surface_n i_o k_n be_v equivalent_a to_o other_o 34_o foot_n and_o therefore_o though_o the_o deepness_n of_o this_o water_n between_o i_o k_o and_o l_o m_o be_v but_o 34_o foot_n real_o yet_o it_o be_v 68_o foot_n virtual_o and_o in_o effect_n imagine_v second_o the_o surface_n i_o k_o to_o subside_v 17_o foot_n namely_o to_o z_o w._n in_o this_o case_n the_o union_n be_v break_v also_o and_o the_o low_a plain_n fall_v from_o the_o upper_a the_o reason_n of_o this_o be_v the_o same_o with_o the_o former_a because_o by_o what_o proportion_n you_o diminish_v the_o high_a of_o the_o superior_a water_n by_o that_o same_o proportion_n you_o diminish_v the_o upward_a pressure_n of_o the_o low_a water_n therefore_o if_o you_o subtract_v from_o the_o superior_a water_n 17_o foot_n that_o weigh_v 100_o pound_n you_o subtract_v likewise_o 100_o pound_n from_o the_o inferior_a water_n and_o consequent_o you_o make_v it_o press_v up_o only_o with_o 300_o but_o 300_o be_v not_o able_a to_o counterpoise_v 352._o let_v we_o suppose_v three_o the_o superior_a plain_n and_o the_o superior_a water_n to_o be_v annihilate_v then_o i_o say_v the_o
plain_n have_v as_o many_o hole_n cut_v through_o it_o answer_v to_o the_o four_o of_o the_o nether_a second_o what_o will_v follow_v if_o the_o nether_a plain_n be_v entire_a and_o four_o bore_v through_o the_o upper_a but_o i_o shall_v supersede_n and_o leave_v these_o to_o be_v gather_v by_o the_o judicious_a reader_n from_o this_o experiment_n we_o see_v first_o that_o the_o broad_a and_o large_a a_o surface_n of_o a_o fluid_a be_v it_o be_v the_o more_o able_a to_o sustain_v a_o burden_n and_o the_o narrow_a it_o be_v it_o be_v the_o less_o able_a second_o that_o each_o part_n of_o a_o surface_n be_v able_a to_o sustain_v so_o much_o weight_n and_o no_o more_o and_o no_o less_o from_o what_o be_v say_v we_o shall_v only_o inâ—err_v this_o conclusion_n that_o equality_n of_o height_n between_o pillar_n of_o a_o fluid_a make_v equal_a pressure_n and_o inequality_n of_o height_n make_v unequal_a pressure_n therefore_o it_o be_v no_o matter_n whether_o they_o be_v gross_a or_o small_a thick_a or_o slender_a provide_v they_o be_v all_o of_o the_o same_o altitude_n experiment_n fourteen_o figure_n 20._o this_o schematism_n represent_v a_o vessel_n full_a of_o water_n 8_o foot_n deep_a e_o f_o be_v a_o glass-pipe_n open_a at_o both_o end_n about_o 9_o foot_n high_a and_o one_o inch_n in_o diameter_n a_o b_o c_o d_o be_v a_o vessel_n of_o glass_n or_o of_o any_o other_o metal_n through_o who_o orifice_n above_o the_o say_a pipe_n come_v down_o b_o h_n i_o be_v a_o pipe_n go_v out_o from_o the_o say_a vessel_n crooked_a with_o a_o right_a angle_n at_o h_n that_o the_o orifice_n i_o may_v look_v upward_o that_o some_o hydrostatical_a conclusion_n may_v be_v infer_v from_o this_o experiment_n fill_v the_o low_a vessel_n a_o b_o c_o d_o with_o quicksilver_n almost_o then_o pour_v in_o as_o much_o water_n above_o it_o as_o will_v fill_v the_o space_n a_o b_o h_n leave_v from_o h_n to_o i_o full_a of_o air._n next_o thrust_v down_o the_o orifice_n of_o the_o pipe_n e_o below_o the_o say_a water_n and_o mercury_n till_o it_o rest_v upon_o the_o bottom_n c_o d._n last_o stop_v well_o with_o cement_n the_o passage_n of_o the_o low_a vessel_n through_o which_o the_o pipe_n come_v down_o that_o neither_o air_n nor_o water_n may_v go_v out_o or_o come_v in_o these_o thing_n be_v do_v let_v down_o this_o engine_n to_o the_o bottom_n of_o the_o large_a vessel_n which_o as_o be_v note_v be_v full_a of_o water_n from_o m_n n_o to_o k_o l_o 8_o foot_n and_o you_o will_v find_v the_o mercury_n to_o rise_v in_o the_o pipe_n from_o a_o b_o to_z g_z 6_o inch_n and_o more_o the_o reason_n be_v because_o there_o be_v a_o pillar_n of_o water_n k_o i_o that_o enter_v the_o orifice_n i_o and_o press_v down_o the_o air_n from_o i_o to_o p_o 3_o inch_n which_o before_o be_v 6._o this_o air_n be_v so_o burden_v instant_o press_v forward_o the_o water_n h_o b_o a_o and_o this_o press_v the_o surface_n of_o the_o stagnant_a mercury_n a_o b_o cause_v the_o liquor_n run_v up_o the_o pipe_n from_o a_o b_o to_z g_z 6_o inch_n the_o reason_n why_o it_o rise_v 6_o inch_n be_v this_o between_o the_o surface_n of_o the_o stagnant_a mercury_n a_o b_o and_o the_o top_n of_o the_o water_n l_o o_fw-fr k_o be_v 84_o inch_n now_o water_n be_v 14_o time_n natural_o light_a than_o mercury_n there_o must_v be_v 14_o inch_n of_o water_n require_v for_o sustain_v one_o inch_n of_o mercury_n and_o consequent_o 84_o for_o support_v 6._o for_o a_o second_o trial_n lift_v up_o the_o whole_a engine_n to_o the_o top_n of_o the_o water_n and_o you_o will_v find_v the_o 6_o inch_n of_o mercury_n b_o g_o sink_n down_o and_o become_v no_o high_o within_o the_o pipe_n than_o the_o surface_n of_o the_o stagnant_a mercury_n a_o b_o without_o the_o reason_n be_v because_o by_o come_v up_o above_o the_o water_n the_o pressure_n of_o the_o water_n k_o i_o be_v take_v away_o from_o the_o orifice_n i_o by_o which_o mean_v the_o compress_a air_n h_n p_o extend_v itself_o to_o i_o liberat_o the_o water_n a_o b_o h_n of_o the_o pressure_n it_o have_v and_o this_o free_v the_o mercury_n of_o its_o pressure_n and_o so_o the_o 6_o inch_n fall_v down_o for_o a_o three_o trial_n stop_v close_o the_o orifice_n i_o and_o let_v all_o down_o as_o before_o in_o this_o case_n you_o will_v find_v no_o ascent_n of_o mercury_n from_o b_o to_z g_z because_o the_o water_n k_o i_o can_v have_v access_n to_o thrust_v down_o the_o air_n from_o i_o to_o p_o as_o former_o for_o a_o four_o open_v the_o say_a orifice_n i_o while_o the_o engine_n be_v below_o the_o water_n and_o you_o will_v find_v the_o mercury_n rise_v from_o b_o to_z g_z because_o the_o pillar_n of_o water_n k_o i_o have_v now_o access_n to_o press_v for_o a_o five_o trial_n stop_v the_o orifice_n i_o and_o bring_v up_o all_o to_o the_o top_n and_o you_o will_v find_v the_o six_o inch_n of_o mercury_n b_o g_z suspend_v as_o if_o the_o engine_n be_v under_o the_o water_n the_o reason_n be_v because_o the_o stop_n of_o the_o orifice_n keep_v the_o enclose_a air_n p_o h_n under_o the_o same_o degree_n of_o pressure_n it_o obtain_v from_o the_o water_n k_o i._o for_o a_o six_o proof_n open_v the_o same_o orifice_n i_o while_o the_o engine_n be_v above_o the_o water_n and_o you_o will_v find_v the_o six_o inch_n of_o mercury_n fall_v down_o because_o the_o imprison_a air_n h_n p_o obtain_v now_o its_o liberty_n and_o expand_v itself_o from_o h_n to_o i_o ease_v the_o water_n b_o h_n of_o the_o burden_n it_o be_v under_o for_o a_o seven_o pour_v in_o 14_o inch_n of_o water_n at_o the_o orifice_n f_o till_o it_o rest_v upon_o the_o top_n of_o the_o mercury_n at_o g_o and_o you_o will_v find_v one_o inch_n fall_v down_o pour_v in_o as_o much_o and_o two_o inch_n fall_v down_o in_o a_o word_n pour_v in_o as_o much_o water_n as_o will_v fill_v the_o pipe_n to_o o_o and_o you_o will_v find_v the_o whole_a six_o inch_n fall_v down_o the_o reason_n be_v because_o the_o water_n k_o i_o be_v not_o able_a to_o sustain_v both_o the_o six_o inch_n of_o mercury_n and_o the_o water_n that_o be_v pour_v in_o any_o one_o of_o they_o be_v able_a and_o sufficient_a to_o counterpoise_v it_o for_o a_o eight_o trial_n empty_z the_o pipe_n of_o the_o say_a water_n and_o after_o the_o mercury_n be_v ascend_v from_o a_o b_o to_z g_z as_o formerly_z suck_v out_o the_o whole_a air_n between_o g_z and_o f_o and_o you_o will_v find_v the_o mercury_n to_o rise_v from_o g_z to_z r_z 29_o inch_n the_o reason_n of_o this_o be_v evident_a from_o the_o pillar_n of_o air_n s_o k_n that_o rest_v upon_o the_o top_n of_o the_o pillar_n of_o water_n k_o i_o for_o by_o suck_v out_o the_o say_a air_n you_o take_v away_o the_o pondus_fw-la or_o weight_n that_o counterpoise_v the_o weight_n of_o the_o pillar_n s_o k_n therefore_o it_o find_v its_o counterpoise_n remove_v present_o cause_v the_o water_n k_o i_o to_o enter_v far_o within_o the_o crooked_a pipe_n till_o it_o have_v press_v up_o the_o liquor_n to_o r._n for_o a_o nine_o trial_n take_v the_o six_o inch_n of_o mercury_n b_o g_o and_o put_v they_o into_o the_o scale_n of_o a_o balance_n then_o take_v as_o much_o water_n as_o will_v fill_v the_o tub_n between_o a_o b_o and_o o_o and_o put_v it_o into_o the_o other_o scale_n and_o you_o will_v find_v a_o most_o exact_a counterbalance_n between_o they_o the_o reason_n be_v because_o if_o the_o water_n k_o h_n or_o a_o pillar_n of_o that_o height_n be_v able_a to_o raise_v and_o counterpoise_v the_o mercury_n b_o g_o then_o must_v as_o much_o water_n as_o fill_v the_o pipe_n between_o b_o and_o o_o be_v the_o just_a weight_n of_o it_o the_o reason_n of_o this_o consequence_n be_v because_o these_o two_o water_n be_v of_o the_o same_o weight_n therefore_o if_o the_o one_o be_v the_o just_a weight_n of_o it_o the_o other_o must_v be_v so_o too_o if_o it_o be_v say_v that_o the_o water_n that_o fill_v the_o pipe_n between_o b_o and_o o_o be_v far_o thick_a than_o the_o water_n k_o h_n therefore_o they_o can_v be_v both_o of_o one_o weight_n i_o answer_v equality_n of_o altitude_n in_o this_o balance_n of_o nature_n be_v equality_n of_o weight_n therefore_o see_v the_o one_o water_n be_v as_o high_a as_o the_o other_o they_o must_v be_v both_o of_o one_o weight_n if_o it_o be_v say_v that_o a_o pillar_n of_o water_n between_o k_o and_o h_n can_v counterpoise_v the_o six_o inch_n of_o mercury_n b_o g_o both_o be_v put_v into_o a_o balance_n and_o the_o reason_n be_v because_o the_o one_o be_v thick_a than_o the_o
much_o mercury_n as_o will_v fill_v between_o x_o o_o and_o z_o f._n for_o understand_v the_o three_o remember_v as_o be_v note_v before_o that_o fluid_a body_n counterpoise_v one_o another_o only_o according_a to_o altitude_n therefore_o it_o be_v no_o matter_n whether_o the_o tub_n be_v wide_a or_o narrow_a if_o it_o be_v inquire_v how_o can_v one_o and_o the_o â—ame_n water_n counterpoise_v two_o fluid_n of_o different_a weight_n to_o say_v that_o fluids_n counterpoise_n one_o another_o according_a to_o altitude_n do_v not_o clear_a the_o difficulty_n for_o it_o still_o remain_v to_o be_v ask_v why_o they_o counterpoise_v one_o another_o after_o this_o manner_n therefore_o it_o seem_v that_o if_o the_o water_n raise_v the_o mercury_n from_o c_o to_o e_z in_o the_o wide_a pipe_n it_o must_v raise_v it_o in_o the_o narrow_a one_o from_o d_o to_o k._n for_o answer_v consider_v first_o that_o as_o there_o be_v here_o two_o pillar_n of_o mercury_n c_o e_o and_o d_o g_z within_z the_o two_o tub_n so_o there_o be_v here_o also_o two_o pillar_n of_o mercury_n a_o p_o and_o b_o q_o under_o the_o two_o orifice_n upon_o which_o the_o say_v two_o pillar_n stand_v and_o rest_n consider_v second_o that_o the_o potentia_fw-la or_o force_n of_o the_o pillar_n a_o p_o be_v just_o equal_a to_o the_o pondus_fw-la of_o the_o pillar_n e_o c_o a_o item_n that_o the_o potentia_fw-la of_o the_o pillar_n b_o q_n be_v equal_a to_o the_o pondus_fw-la g_o d_o b._n three_o that_o the_o potentia_fw-la of_o a_o p._n be_v most_o exact_o equal_v to_o the_o potentia_fw-la of_o b_o q_o and_o the_o reason_n be_v because_o their_o top_n a_o and_o b_o be_v part_n of_o the_o same_o horizontal_a surface_n i_o say_v then_o if_o a_o p_o be_v equal_a to_o e_o c_o a_o and_o b_o qui_fw-fr equal_a to_o g_o d_o b_o and_o a_o p_o and_o b_o q_n equal_a among_o themselves_o then_o must_v e_o c_o at_fw-fr be_v equal_a to_o g_o d_o b._n the_o same_o water_n then_o do_v not_o counterpoise_v two_o body_n of_o different_a weight_n i_o grant_v e_o c_o a_o to_o be_v far_o heavy_a than_o g_o d_o b_o while_o they_o be_v weigh_v in_o a_o pair_n of_o scale_n but_o the_o one_o be_v not_o heavy_a than_o the_o other_o as_o they_o be_v weigh_v in_o this_o balance_n of_o nature_n from_o what_o be_v say_v we_o see_v first_o that_o in_o water_n there_o be_v a_o pressure_n and_o a_o considerable_a weight_n this_o be_v evident_a from_o the_o rise_n of_o the_o mercury_n we_o see_v second_o that_o fluids_n counterpoise_n one_o another_o only_o according_a to_o altitude_n three_o that_o when_o a_o light_a fluid_n press_v up_o a_o heavy_a there_o be_v no_o more_o press_v up_o of_o it_o than_o be_v the_o just_a weight_n of_o the_o press_a fluid_n because_o the_o mercury_n e_o c_o be_v just_a the_o weight_n of_o the_o water_n that_o press_v upon_o x_o y_o o._n that_o be_v to_o say_v the_o part_n of_o the_o surface_n c_o be_v no_o more_o press_v with_o the_o mercury_n e_o c_o than_o the_o part_n x_o be_v press_v with_o the_o water_n l_o z_o x._o four_o if_o mercury_n be_v 28_o time_n heavy_a than_o water_n only_o three_o inch_n will_v be_v press_v up_o if_o it_o be_v but_o seven_o time_n heavy_a the_o altitude_n will_v be_v at_o saint_n 12_o inch_n above_o c._n five_o it_o be_v as_o easy_a for_o a_o large_a part_n of_o a_o surface_n to_o sustain_v a_o large_a pillar_n as_o it_o be_v for_o a_o narrow_a part_n to_o sustain_v a_o narrow_a pillar_n because_o a_o p_o sustain_v e_o c_o a_o as_o easy_o as_o b_o qui_fw-fr sustain_v g_o d_o b._n sixthly_a that_o in_o fluids_n there_o be_v a_o pondus_fw-la and_o a_o potentia_fw-la as_o be_v clear_a from_o the_o potentia_fw-la of_o a_o p_o that_o sustain_v the_o pondus_fw-la of_o e_o c_o a._n the_o water_n likewise_o that_o sustain_v have_v a_o potentia_fw-la and_o the_o mercury_n e_o c_o be_v the_o pondus_fw-la of_o it_o seven_o that_o there_o be_v always_o equality_n of_o weight_n between_o the_o pondus_fw-la and_o the_o potentia_fw-la so_o be_v the_o potentia_fw-la of_o a_o p_o equal_a to_o the_o pondus_fw-la e_o c_o a._n eighthly_a that_o the_o pondus_fw-la beget_v the_o potentia_fw-la so_o the_o weight_n of_o the_o water_n beget_v the_o potentia_fw-la that_n in_o a_o p._n for_o make_v this_o water_n deep_o and_o you_o augment_v the_o potentia_fw-la of_o a_o p._n if_o you_o subtract_v from_o it_o the_o potentia_fw-la of_o a_o p_o grow_v less_o by_o proportion_n or_o the_o weight_n of_o e_o c_o a_o may_v be_v say_v to_o beget_v the_o potentia_fw-la of_o a_o p._n to_o proceed_v a_o little_a further_o let_v we_o suppose_v the_o air_n h_o e_z to_o be_v remove_v in_o this_o case_n the_o mercury_n rise_v 29_o inch_n high_o than_o e_z or_o 35_o above_o c_o even_o as_o high_a as_o s._n in_o the_o narrow_a tub_n it_o will_v climb_v up_o to_o k_o if_o you_o take_v away_o the_o air_n i_o g._n this_o come_v to_o pass_v by_o virtue_n of_o the_o pressure_n of_o the_o atmosphere_n that_o rest_v upon_o l_o n._n from_o this_o we_o gather_v ninthly_a that_o there_o be_v a_o counterpoise_n between_o the_o air_n h_o e_o and_o the_o weight_n of_o the_o air_n that_o rest_v upon_o l_o n_o and_o that_o a_o slender_a pillar_n of_o air_n be_v able_a to_o counterpoise_v a_o thick_a for_o h_n e_z be_v far_o narrow_a than_o l_o n._n ten_o that_o the_o pressure_n of_o the_o air_n can_v be_v communicate_v through_o divers_a kind_n of_o fluid_n because_o the_o weight_n that_o rest_v upon_o l_o n_o be_v send_v down_o through_o the_o water_n l_o z_o x_o and_o down_o through_o the_o stagnant_a mercury_n and_o thrust_v up_o the_o liquor_n from_o a_o to_o saint_n 35_o inch_n eleven_o that_o a_o light_a fluid_n may_v be_v make_v to_o press_v with_o great_a burden_n than_o a_o fluid_a natural_o heavy_a because_o the_o weight_n of_o the_o air_n upon_o l_o n_o raises_z 29_o inch_n of_o mercury_n but_o the_o water_n raise_v only_o six_o we_o see_v twelfthly_a that_o fluids_n have_v a_o sphere_n of_o activity_n to_o which_o they_o be_v able_a to_o press_v up_o themselves_o or_o fluid_n of_o different_a kind_n because_o first_o the_o stagnant_a mercury_n can_v raise_v itself_o no_o high_o within_o the_o pipe_n than_o it_o be_v without_o next_o the_o 84_o inch_n of_o water_n can_v raise_v the_o mercury_n no_o high_o than_o e._n last_o the_o weight_n of_o the_o atmosphere_n can_v raise_v the_o mercury_n no_o high_o than_o saint_n 29_o inch_n above_o e._n for_o another_o trial_n take_v out_o from_o among_o the_o water_n the_o two_o pipe_n and_o stop_v close_o the_o two_o under_o orifice_n fill_v they_o with_o mercury_n to_o the_o brim_n then_o thrust_v they_o down_o as_o before_o and_o open_v the_o say_v two_o orifice_n while_o they_o be_v below_o the_o surface_n x_o in_n o_o and_o you_o will_v find_v the_o whole_a cylinder_n fall_n down_o from_o h_n to_o e_z and_o there_o halt_v and_o the_o whole_a cylinder_n in_o the_o narrow_a pipe_n fall_v down_o from_o i_o to_o g._n or_o if_o you_o please_v before_o this_o be_v do_v stop_v close_o the_o orifice_n h_n and_o the_o orifice_n i_o and_o you_o will_v find_v the_o mercury_n go_v no_o further_o down_o than_o saint_n by_o open_v the_o orifice_n a_o and_o no_o further_o down_o than_o k_o by_o open_v the_o orifice_n b._n this_o lead_v we_o to_o a_o clear_a discovery_n of_o the_o reason_n why_o the_o mercury_n subside_v and_o sink_v down_o from_o the_o top_n of_o the_o tub_n in_o the_o baroscope_n to_o the_o 29_o inch_n whatever_o the_o diameter_n of_o the_o pipe_n be_v and_o this_o let_v we_o see_v that_o the_o mercurial_a cylinder_n be_v suspend_v by_o the_o air_n after_o the_o same_o manner_n that_o the_o mercury_n e_o c_o be_v suspend_v after_o and_o that_o there_o be_v no_o more_o difficulty_n in_o the_o one_o than_o in_o the_o other_o experiment_n xvii_o figure_n 23_o 24._o this_o schematism_n represent_v a_o water_n 30_o fathom_n deep_a under_o the_o first_o surface_n a_o there_o be_v six_o imaginary_a as_o b_o c_o d_o e_o f_o g_o every_o one_o whereof_o be_v five_o fathom_v below_o another_o there_o be_v here_o likewise_o two_o glass_n each_o one_o 12_o inch_n high_a and_o 5_o inch_n broad_a like_a unto_o these_o wherein_o wine_n sack_n or_o brandy_n be_v preserve_v the_o glass_n g_o m_o have_v its_o orifice_n g_z upward_o the_o other_o glass_n be_v complete_o open_v below_o without_o a_o narrow_a orifice_n for_o make_v experiment_n take_v a_o long_a chord_n as_o long_o as_o the_o water_n be_v in_o deepness_n and_o knit_v the_o end_n of_o it_o round_o about_o the_o neck_n of_o the_o glass_n at_o g._n take_v another_o line_n of_o the_o same_o length_n and_o
sink_v a_o man_n may_v perceive_v distinct_o what_o be_v lie_v in_o the_o bottom_n so_o clear_a and_o transparent_a be_v the_o air_n of_o it_o but_o when_o the_o damp_n be_v go_v the_o medium_fw-la be_v not_o so_o clear_a in_o temperate_a and_o cold_a weather_n the_o damp_n be_v not_o so_o frequent_a from_o this_o sink_v in_o soft_a wind_n or_o in_o northerly_a wind_n or_o when_o it_o blow_v from_o east_n or_o north-east_n the_o damp_n be_v drive_v away_o observation_n ii_o jupiter_n upon_o wednesday_n night_n at_o eleven_o a_o clock_n be_v 24_o of_o november_n 1669_o have_v the_o follow_a position_n with_o the_o star_n of_o gemini_fw-la he_o be_v so_o near_o to_o the_o star_n c_o that_o to_o appearance_n the_o point_n of_o his_o ray_n do_v touch_v it_o this_o star_n by_o look_v upon_o the_o material_a glob_n be_v fix_v in_o the_o very_a zodiac_n and_o in_o the_o 13_o degree_n of_o cancer_n and_o be_v the_o very_a navel_n of_o the_o follow_a twine_n the_o star_n a_o be_v castor_n the_o star_n b_o be_v pollux_n the_o star_n d_o be_v fix_v in_o the_o forefoot_n of_o the_o follow_a twine_n from_o this_o place_n he_o move_v with_o a_o retrograde_a motion_n till_o he_o come_v to_o the_o 5_o of_o cancer_n about_o the_o 20_o of_o february_n 1670_o and_o from_o that_o time_n become_v direct_a in_o his_o motion_n and_o so_o upon_o the_o 27_o of_o march_n 1670_o at_o 9_o a_o clock_n he_o be_v in_o a_o right_a line_n with_o canis_fw-la minor_fw-la and_o the_o bright_a star_n in_o auriga_fw-la and_o be_v in_o a_o right_a line_n with_o the_o eastmost_a shoulder_n of_o orion_n and_o castor_n in_o gemini_fw-la or_o with_o that_o star_n when_o south-west_n that_o be_v high_a and_o west-most_a observation_n iii_o it_o be_v write_v in_o the_o history_n of_o the_o royal_a society_n that_o such_o a_o member_n of_o it_o who_o name_n i_o have_v forget_v have_v find_v out_o among_o many_o other_o curious_a invention_n this_o namely_o a_o way_n for_o know_v the_o motion_n of_o the_o sun_n 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