of_o the_o cause_n of_o attraction_n by_o suction_n a_o paradox_n by_o the_o honourable_a robert_n boyle_n fellow_n of_o the_o royal_a society_n london_n print_v by_o william_n godbid_v and_o be_v to_o be_v sell_v by_o moses_n pitt_n at_o the_o angel_n over_o against_o the_o little_a north_n door_n of_o st._n paul_n church_n 1674._o preface_n have_v about_o twelve_o year_n ago_o summary_o express_v and_o publish_v my_o opinion_n of_o the_o cause_n of_o suction_n and_o a_o while_n before_o or_o after_o bring_v to_o the_o royal_a society_n the_o glass_n instrument_n i_o employ_v to_o make_v it_o out_o i_o desist_v for_o some_o time_n to_o add_v any_o thing_n about_o a_o problem_n that_o i_o have_v but_o occasional_o handle_v only_o because_o the_o instrument_n i_o mention_v in_o my_o examen_fw-la of_o mr._n hobbes_n opinion_n and_o afterward_o use_v at_o gresham-college_n be_v difficult_a enough_o to_o be_v well_o make_v and_o not_o to_o be_v procure_v ready_o make_v i_o do_v for_o the_o sake_n of_o some_o virtuoso_n that_o be_v curious_a of_o such_o thing_n devise_v a_o slight_a and_o easy_o make_v instrument_n describe_v in_o the_o follow_a tract_n chap._n 4_o in_o which_o the_o chief_a phaenomena_n i_o show_v before_o the_o society_n be_v easy_o producible_a but_o afterward_o the_o mistake_n and_o erroneous_a opinion_n that_o in_o print_n as_o well_o as_o in_o discourse_n i_o meet_v with_o even_o among_o learned_a man_n about_o suction_n and_o the_o curiosity_n of_o a_o ingenious_a person_n engage_v i_o to_o resume_v that_o subject_a and_o treat_v of_o it_o as_o if_o i_o have_v never_o before_o meddle_v with_o it_o for_o the_o reason_n intimate_v in_o the_o begin_n of_o the_o ensue_a paper_n and_o find_v upon_o the_o review_n of_o my_o late_a animadversion_n on_o mr._n hobbes_n problemata_fw-la de_fw-fr vacuo_fw-la that_o some_o passage_n of_o this_o tract_n be_v refer_v to_o there_o i_o see_v myself_o thereby_o little_o less_o than_o engage_v to_o annex_v that_o discourse_n to_o those_o animadversion_n and_o this_o i_o the_o rather_o consent_v to_o because_o it_o contain_v some_o experiment_n that_o i_o have_v not_o elsewhere_o meet_v with_o which_o together_o with_o some_o other_o part_n of_o that_o essay_n may_v i_o hope_v prove_v of_o some_o use_n to_o illustrate_v and_o confirm_v our_o doctrine_n about_o the_o weight_n and_o spring_n of_o the_o air_n and_o supply_v the_o less_o experience_v than_o ingenious_a friend_n to_o our_o hypothesis_n with_o more_o ground_n of_o answer_v the_o late_a objection_n of_o some_o learned_a man_n against_o who_o endeavour_n i_o perceive_v it_o will_v be_v useful_a to_o employ_v variety_n of_o experiment_n and_o other_o proof_n to_o evince_v the_o same_o truth_n that_o some_o or_o other_o of_o these_o may_v meet_v with_o those_o argument_n or_o evasion_n with_o which_o they_o strive_v to_o elude_v the_o force_n of_o the_o rest_n the_o title_n of_o the_o follow_a essay_n may_v sufficient_o keep_v the_o reader_n from_o expect_v to_o find_v any_o other_o kind_n of_o attraction_n discourse_v of_o than_o that_o which_o be_v make_v by_o suction_n but_o yet_o thus_o much_o i_o shall_v here_o intimate_v in_o general_n that_o i_o have_v find_v by_o trial_n purposely_o make_v that_o the_o example_n of_o suction_n be_v not_o the_o only_o note_v one_o of_o attraction_n that_o may_v be_v reduce_v to_o pulsion_n of_o the_o cause_n of_o attraction_n by_o suction_n a_o paradox_n chap._n i._n i_o may_v sir_n save_v myself_o some_o trouble_n in_o give_v you_o that_o account_v you_o desire_v of_o i_o about_o suction_n by_o refer_v you_o to_o a_o passage_n in_o the_o examen_fw-la i_o long_o since_o write_v of_o mr._n hobbes_n dialogus_fw-la physicus_fw-la de_fw-la natura_fw-la aeris_fw-la if_o i_o know_v you_o have_v those_o two_o book_n lie_v by_o you_o but_o because_o i_o suspect_v that_o my_o examen_fw-la may_v not_o be_v in_o your_o hand_n since_o it_o be_v almost_o out_o of_o print_n and_o have_v not_o for_o some_o year_n be_v in_o my_o own_o and_o because_o i_o do_v not_o so_o well_o remember_v after_o so_o long_a a_o time_n the_o particular_n that_o i_o write_v there_o about_o suction_n as_o i_o do_v in_o general_n that_o the_o hypothesis_n i_o propose_v be_v very_o incidental_o and_o brief_o discourse_v of_o upon_o a_o occasion_n minister_v by_o a_o wrong_a explication_n give_v of_o suction_n by_o mr._n hobbes_n i_o shall_v here_o decline_v refer_v you_o to_o what_o i_o there_o write_v and_o propose_v to_o you_o those_o thought_n about_o suction_n that_o i_o remember_v i_o there_o point_v at_o i_o shall_v annex_v some_o thing_n to_o illustrate_v and_o confirm_v they_o that_o will_v not_o have_v be_v so_o proper_a for_o i_o to_o have_v insist_v on_o in_o a_o short_a and_o but_o occasional_a excursion_n and_o i_o shall_v immediate_o proceed_v to_o what_o you_o expect_v from_o i_o but_o that_o suction_n be_v general_o look_v upon_o as_o a_o kind_n of_o attraction_n it_o will_v be_v requisite_a for_o i_o to_o premise_v something_o about_o attraction_n itself_o for_o beside_o that_o the_o cause_n of_o it_o which_o i_o here_o dispute_v not_o of_o be_v obscure_a the_o very_a nature_n and_o notion_n of_o it_o be_v wont_n by_o naturalist_n to_o be_v either_o left_a untouched_a or_o but_o very_o dark_o deliver_v and_o therefore_o will_v not_o be_v unfit_a to_o be_v here_o somewhat_o explain_v how_o general_a and_o ancient_a soever_o the_o common_a opinion_n may_v be_v that_o attraction_n be_v a_o kind_n of_o motion_n quite_o differ_v from_o pulsion_n if_o not_o also_o opposite_a to_o it_o yet_o i_o confess_v i_o concur_v in_o opinion_n though_o not_o altogether_o upon_o the_o same_o ground_n with_o some_o modern_a naturalist_n that_o think_v attraction_n a_o species_n of_o pulsion_n and_o at_o least_o among_o inanimate_a body_n i_o have_v not_o yet_o observe_v any_o thing_n that_o convince_v i_o that_o attraction_n can_v be_v reduce_v to_o pulsion_n for_o these_o two_o seem_v to_o i_o to_o be_v but_o extrinsical_a denomination_n of_o the_o same_o local_a motion_n in_o which_o if_o a_o move_v body_n precede_v the_o movent_fw-la or_o tend_v to_o acquire_v a_o great_a distance_n from_o it_o we_o call_v it_o pulsion_n and_o if_o upon_o the_o score_n of_o the_o motion_n the_o same_o body_n follow_v the_o movent_fw-la or_o approach_v to_o it_o we_o call_v it_o attraction_n but_o this_o difference_n may_v consist_v but_o in_o a_o accidental_a respect_n which_o do_v not_o physical_o alter_v the_o nature_n of_o the_o motion_n but_o be_v found_v upon_o the_o respect_n which_o the_o line_n wherein_o the_o motion_n be_v make_v happen_v to_o have_v to_o the_o situation_n of_o the_o movent_fw-la and_o that_o which_o seem_v to_o i_o to_o have_v be_v the_o chief_a cause_n of_o man_n mistake_v attraction_n for_o a_o motion_n opposite_a to_o pulsion_n be_v that_o they_o have_v look_v upon_o both_o the_o move_n and_o move_v body_n in_o too_o popular_a and_o superficial_a a_o manner_n and_o consider_v in_o the_o movent_fw-la rather_o the_o situation_n of_o the_o conspicuous_a and_o more_o bulky_a part_n of_o the_o animal_n or_o other_o agent_n than_o the_o situation_n of_o that_o part_n of_o the_o animal_n or_o instrument_n that_o do_v immediate_o impress_v that_o motion_n upon_o the_o mobile_n for_o those_o that_o attentive_o heed_v this_o may_v easy_o take_v notice_n that_o some_o part_n of_o that_o body_n or_o of_o the_o instrument_n which_o by_o reason_n of_o their_o conjunction_n in_o this_o operation_n be_v to_o be_v look_v on_o but_o as_o make_v one_o with_o it_o be_v real_o place_v behind_o some_o part_n of_o the_o body_n to_o be_v draw_v and_o therefore_o can_v move_v outward_o itself_o without_o thrust_v that_o body_n forward_o this_o will_v be_v easy_o understand_v if_o we_o consider_v what_o happen_v when_o a_o man_n draw_v a_o chain_n after_o he_o for_o though_o his_o body_n do_v precede_v the_o chain_n yet_o his_o finger_n or_o some_o other_o part_n of_o the_o hand_n wherewith_o he_o draw_v it_o have_v some_o part_n or_o other_o that_o reach_v behind_o the_o fore_a part_n of_o the_o first_o link_n and_o the_o hinder_a part_n of_o this_o link_n come_v behind_o the_o anteriour_a part_n of_o the_o second_o link_n and_o so_o each_o link_n have_v one_o of_o its_o part_n place_v behind_o some_o part_n of_o the_o link_n next_o after_o it_o till_o you_o come_v to_o the_o last_o link_n of_o all_o and_o so_o as_o the_o finger_n that_o be_v in_o the_o first_o link_n can_v move_v forward_o but_o it_o must_v thrust_v on_o that_o link_n by_o this_o series_n of_o trusion_n the_o whole_a chain_n be_v move_v forward_o and_o if_o any_o other_o body_n be_v draw_v by_o that_o chain_n you_o may_v perceive_v that_o some_o part_n of_o the_o last_o link_n come_v behind_o some_o part_n of_o that_o
body_n or_o of_o some_o intervening_a body_n which_o by_o its_o cohesion_n with_o it_o aught_o in_o our_o present_a case_n to_o be_v consider_v as_o part_v of_o it_o and_o thus_o attraction_n seem_v to_o be_v but_o a_o species_n of_o pulsion_n and_o usual_o belong_v to_o that_o kind_a of_o it_o which_o for_o distinction_n sake_n be_v call_v trusion_n by_o which_o we_o understand_v that_o kind_n of_o pulsion_n wherein_o the_o movent_fw-la go_v along_o with_o the_o move_a body_n without_o quit_v it_o whilst_o the_o progress_n last_v as_o it_o happen_v when_o a_o gardener_n drive_v his_o wheel-barrow_n before_o he_o without_o let_v go_v his_o hold_n of_o it_o but_o i_o must_v not_o here_o dissemble_v a_o difficulty_n that_o i_o foresee_v may_v be_v specious_o urge_v against_o this_o account_n of_o attraction_n for_o it_o may_v be_v say_v that_o there_o be_v attraction_n where_o it_o can_v be_v pretend_v that_o any_o part_n of_o the_o attrahent_fw-la come_v behind_o the_o attract_v body_n as_o in_o magnetical_a and_o electrical_a attraction_n and_o in_o that_o which_o be_v make_v of_o water_n when_o it_o be_v draw_v up_o into_o spring_n and_o pump_n i_o need_v not_o tell_v you_o that_o you_o know_v so_o well_o as_o that_o partly_o the_o cartesian_o and_o partly_o other_o modern_a philosopher_n have_v recourse_n on_o this_o occasion_n either_o to_o screw_v particle_n and_o other_o magnetical_a emission_n to_o explicate_v phaenomena_n of_o this_o kind_n and_o according_a to_o such_o hypothesis_n one_o may_v say_v that_o many_o of_o these_o magnetical_a and_o electrical_a effluvia_fw-la come_v behind_o some_o part_n of_o the_o attract_a body_n or_o at_o least_o of_o the_o little_a solid_a particle_n that_o be_v as_o it_o be_v the_o wall_n of_o their_o pore_n or_o procure_v some_o discussion_n of_o the_o air_n that_o may_v make_v it_o thrust_v the_o movable_a towards_o the_o loadstone_n or_o amber_n etc._n etc._n but_o if_o there_o be_v none_o of_o these_o nor_o any_o other_o subtle_a agent_n that_o cause_v this_o motion_n by_o a_o real_a though_o unperceived_a pulsion_n i_o shall_v make_v a_o distinction_n betwixt_o other_o attraction_n and_o these_o which_o i_o shall_v then_o style_v attraction_n by_o invisibles_n but_o whether_o there_o be_v real_o any_o such_o in_o nature_n and_o why_o i_o scruple_n to_o admit_v thing_n so_o hard_o to_o be_v conceive_v may_v be_v elsewhere_o consider_v and_o you_o will_v i_o presume_v the_o free_o allow_v i_o this_o liberty_n if_o since_o in_o this_o place_n it_o be_v proper_a to_o do_v it_o i_o show_v you_o that_o in_o the_o last_o of_o the_o instance_n i_o former_o object_v that_o of_o the_o draw_v up_o of_o water_n into_o the_o barrel_n of_o a_o syringe_n there_o be_v no_o true_a attraction_n of_o the_o liquor_n make_v by_o the_o external_a air._n i_o say_v then_o that_o by_o the_o ascend_a rammer_n as_o a_o part_n of_o which_o i_o here_o consider_v the_o obtuse_a end_n plug_n or_o sucker_n there_o be_v no_o attraction_n make_v of_o the_o contiguous_a and_o subjacent_a water_n but_o only_o there_o be_v room_n make_v for_o it_o to_o rise_v into_o without_o be_v expose_v to_o the_o pressure_n of_o the_o supeiour_n air._n for_o if_o we_o suppose_v the_o whole_a rammer_n to_o be_v by_o divine_a omnipotence_n annihilate_v and_o consequent_o uncapable_a of_o exercise_v any_o attraction_n yet_o provide_v the_o superior_a air_n be_v keep_v off_o from_o the_o water_n by_o any_o other_o way_n as_o well_o as_o it_o be_v by_o the_o rammer_n the_o liquor_n will_v as_o well_o ascend_v into_o the_o cavity_n of_o the_o barrel_n since_o as_o i_o have_v elsewhere_o abundant_o prove_v the_o surface_n of_o the_o terraqueous_a globe_n be_v continual_o press_v on_o by_o the_o incumbent_a air_n or_o atmosphere_n the_o water_n must_v be_v by_o that_o pressure_n impel_v into_o any_o cavity_n here_o below_o where_o there_o be_v no_o air_n to_o resist_v it_o as_o by_o our_o supposition_n there_o be_v not_o in_o the_o barrel_n of_o our_o syringe_n when_o the_o rammer_n or_o whatever_o else_o be_v in_o it_o have_v be_v annihilate_v which_o reason_v may_v be_v sufficient_o confirm_v by_o a_o experiment_n whereby_o i_o have_v more_o than_o once_o show_v some_o curious_a person_n that_o if_o the_o external_a air_n and_o consequent_o its_o pressure_n be_v withdraw_v from_o about_o the_o syringe_n one_o may_v pull_v up_o the_o sucker_n as_o much_o as_o he_o please_v without_o draw_v up_o after_o it_o the_o subjacent_a water_n in_o short_a let_v we_o suppose_v that_o a_o man_n stand_v in_o a_o inner_a room_n do_v by_o his_o utmost_a resistance_n keep_v shut_v a_o door_n that_o be_v neither_o lock_v nor_o latch_a against_o another_o who_o with_o equal_a force_n endeavour_n to_o thrust_v it_o open_a in_o this_o case_n as_o if_o one_o shall_v forcible_o pull_v away_o the_o first_o man_n it_o can_v not_o be_v say_v that_o this_o man_n by_o his_o recess_n from_o the_o door_n he_o endeavour_v to_o press_v outward_o do_v true_o and_o proper_o draw_v in_o his_o antagonist_n though_o upon_o that_o recess_n the_o come_n in_o of_o his_o antagonist_n will_v present_o ensue_v so_o it_o can_v proper_o be_v say_v that_o by_o the_o ascent_n of_o the_o rammer_n which_o displace_v the_o superior_a air_n either_o the_o rammer_n itself_o or_o the_o expel_v air_n do_v proper_o attract_v the_o subjacent_a water_n though_o the_o ingress_n of_o that_o liquor_n into_o the_o barrel_n do_v thereupon_o necessary_o ensue_v and_o that_o as_o the_o comparison_n suppose_v there_o be_v a_o pressure_n of_o the_o superior_a air_n against_o the_o upper_a part_n of_o the_o sucker_n you_o may_v easy_o perceive_v if_o have_v well_o stop_v the_o low_a orifice_n of_o the_o syringe_n with_o your_o finger_n you_o forcible_o draw_v up_o the_o sucker_n to_o the_o top_n of_o the_o barrel_n for_o if_o then_o you_o let_v go_v the_o rammer_n you_o will_v find_v it_o impel_v downward_o by_o the_o incumbent_a air_n with_o a_o notable_a force_n chap._n ii_o have_v thus_o premise_v something_o in_o general_n about_o the_o nature_n of_o attraction_n as_o far_o as_o it_o be_v necessary_a for_o my_o present_a design_n it_o will_v be_v now_o seasonable_a to_o proceed_v to_o the_o consideration_n of_o that_o kind_n of_o attraction_n that_o be_v employ_v to_o raise_v liquor_n and_o be_v by_o a_o distinct_a name_n call_v suction_n about_o the_o cause_n of_o this_o there_o be_v great_a contention_n between_o the_o new_a philosopher_n as_o they_o be_v style_v and_o the_o peripatetic_n for_o the_o follower_n of_o aristotle_n and_o many_o learned_a man_n that_o in_o other_o thing_n dissent_v from_o he_o ascribe_v the_o ascension_n of_o liquor_n upon_o suction_n to_o nature_n abhorrence_n of_o a_o vacuum_n for_o say_v they_o when_o a_o man_n dip_v one_o end_n of_o a_o straw_n or_o reed_n into_o stagnant_a water_n and_o suck_v at_o the_o other_o end_n the_o air_n contain_v in_o the_o cavity_n of_o the_o reed_n pass_v into_o that_o of_o his_o lung_n and_o consequent_o the_o reed_n will_v be_v leave_v empty_a if_o no_o other_o body_n succeed_v in_o the_o place_n it_o desert_n but_o there_o be_v only_o that_o they_o take_v notice_n of_o two_o body_n that_o can_v succeed_v the_o air_n and_o the_o grosser_n liquor_n the_o water_n and_o the_o air_n can_v do_v it_o because_o of_o the_o interposition_n of_o the_o water_n that_o deny_v it_o access_n to_o the_o immersed_a orifice_n of_o the_o reed_n and_o therefore_o it_o must_v be_v the_o water_n itself_o which_o according_o do_v ascend_v to_o prevent_v a_o vacuum_n detest_a by_o nature_n but_o many_o of_o the_o modern_a philosopher_n and_o general_o all_o the_o corpuscularian_o look_v upon_o this_o fuga_fw-la vacui_fw-la as_o but_o a_o imaginary_a cause_n of_o suction_n though_o they_o do_v it_o upon_o very_o differ_v ground_n for_o the_o atomist_n that_o willing_o admit_v of_o vacuity_n proper_o so_o call_v both_o within_o and_o without_o our_o world_n can_v think_v that_o nature_n hate_v or_o fear_v a_o vacuum_n and_o decline_v her_o usual_a course_n to_o prevent_v it_o and_o the_o cartesian_o though_o they_o do_v as_o well_o as_o the_o peripatetic_n deny_v that_o there_o be_v a_o vacuum_n yet_o since_o they_o affirm_v not_o only_o that_o there_o be_v none_o in_o rerum_fw-la natura_fw-la but_o that_o there_o can_v be_v none_o because_o what_o other_o call_v a_o empty_a space_n have_v three_o dimension_n have_v all_o that_o they_o think_v belong_v to_o the_o essence_n of_o a_o body_n they_o will_v not_o grant_v nature_n to_o be_v so_o indiscreet_a as_o to_o strain_v herself_o to_o prevent_v the_o make_n of_o a_o thing_n that_o be_v impossible_a to_o be_v make_v the_o peripatetic_a opinion_n about_o the_o cause_n of_o suction_n though_o common_o defend_v by_o the_o school_n as_o well_o modern_a as_o ancient_n
which_o be_v one_o of_o the_o two_o thing_n i_o chief_o intend_v that_o there_o may_v be_v case_n wherein_o the_o cause_n assign_v in_o the_o hypothesis_n i_o be_o examine_v will_v not_o have_v place_n but_o this_o will_v be_v better_o understand_v if_o before_o i_o proceed_v to_o the_o proof_n of_o it_o i_o propose_v to_o you_o the_o thought_n i_o have_v many_o year_n since_o and_o do_v still_o retain_v about_o the_o cause_n of_o the_o ascension_n of_o liquor_n in_o suction_n to_o clear_v the_o way_n to_o the_o right_a understanding_n of_o the_o ensue_a discourse_n it_o will_v not_o be_v amiss_o here_o to_o premise_v a_o summary_n intimation_n of_o some_o thing_n that_o be_v suppose_v in_o our_o hypothesis_n we_o suppose_v then_o first_o without_o dispute_v either_o the_o existence_n or_o the_o nature_n of_o elementary_a air_n that_o the_o common_a air_n we_o breath_n in_o and_o which_o i_o often_o call_v atmospherical_a air_n abound_v with_o corpuscle_n not_o devoid_a of_o weight_n and_o endow_v with_o elasticity_n or_o springiness_n whereby_o the_o low_a part_n compress_v by_o the_o weight_n of_o the_o upper_a incessant_o endeavour_v to_o expand_v themselves_o by_o which_o expansion_n and_o in_o proportion_n to_o it_o the_o spring_n of_o the_o air_n be_v weaken_a as_o other_o spring_n be_v wont_a to_o be_v the_o more_o they_o be_v permit_v to_o stretch_v themselves_o next_o we_o suppose_v that_o the_o terraqueous_a globe_n be_v environ_v with_o this_o gravitate_v and_o springy_a air_n have_v its_o surface_n and_o the_o body_n place_v on_o it_o press_v by_o as_o much_o of_o the_o atmosphere_n as_o either_o perpendicular_o lean_v on_o they_o or_o can_v otherwise_o come_v to_o bear_v upon_o they_o and_o this_o pressure_n be_v by_o the_o turricellian_a and_o other_o experiment_n find_v to_o be_v equivalent_a to_o a_o perpendicular_o erect_v cylinder_n of_o about_o twenty_o nine_o or_o thirty_o inch_n of_o quicksilver_n for_o the_o height_n be_v differ_v as_o the_o gravity_n of_o the_o atmosphere_n happen_v to_o be_v various_a last_o we_o suppose_v that_o air_n be_v contain_v in_o a_o pipe_n or_o other_o hollow_a body_n that_o have_v but_o one_o orifice_n open_a to_o the_o free_a air_n if_o this_o orifice_n be_v hermetical_o seal_v or_o otherwise_o as_o with_o the_o mouth_n of_o one_o that_o suck_v close_v the_o now_o include_v air_n whilst_o it_o continue_v without_o any_o far_a expansion_n will_v have_v a_o elasticity_n equivalent_a to_o the_o weight_n of_o as_o much_o of_o the_o outward_a air_n as_o do_v before_o press_v against_o it_o for_o if_o the_o weight_n of_o the_o atmosphere_n to_o which_o it_o be_v then_o expose_v have_v be_v able_a to_o compress_v it_o further_o it_o will_v have_v do_v so_o and_o then_o the_o close_n of_o the_o orifice_n at_o which_o the_o internal_a and_o external_a air_n communicate_v as_o it_o fence_v the_o include_v air_n from_o the_o pressure_n of_o the_o incumbent_n so_o it_o hinder_v the_o same_o include_v air_n from_o expand_v itself_o so_o that_o as_o it_o be_v shut_v up_o with_o the_o pressure_n of_o the_o atmosphere_n upon_o it_o that_o be_v in_o a_o state_n of_o as_o great_a compression_n as_o the_o weight_n of_o the_o atmosphere_n can_v bring_v it_o to_o so_o be_v shut_v up_o and_o thereby_o keep_v from_o weaken_v that_o pressure_n by_o expansion_n it_o must_v retain_v a_o springiness_n equipollent_a to_o the_o pressure_n it_o be_v expose_v to_o before_o which_o as_o i_o just_a now_o note_v be_v as_o great_a as_o the_o weight_n of_o the_o incumbent_a pillar_n of_o the_o atmosphere_n can_v make_v it_o but_o if_o as_o be_v say_v in_o the_o first_o supposition_n the_o include_v air_n shall_v come_v to_o be_v dilate_v or_o expanded_a the_o spring_n be_v then_o unbend_v its_o spring_n like_o that_o of_o other_o elastical_a body_n will_v be_v debilitate_a answerable_o to_o that_o expansion_n to_o i_o than_o it_o seem_v that_o speak_v in_o general_n liquor_n be_v upon_o suction_n raise_v into_o the_o cavity_n of_o pipe_n and_o other_o hollow_a body_n when_o and_o so_o far_o as_o there_o be_v a_o less_o pressure_n on_o the_o surface_n of_o the_o liquor_n in_o the_o cavity_n than_o on_o the_o surface_n of_o the_o external_a liquor_n that_o surround_v the_o pipe_n whether_o that_o pressure_n on_o those_o part_n of_o the_o external_a liquor_n that_o be_v from_o time_n to_o time_n impel_v up_o into_o the_o orifice_n of_o the_o pipe_n proceed_v from_o the_o weight_n of_o the_o atmosphere_n or_o the_o propagate_v compression_n or_o impulse_n of_o some_o part_n of_o the_o air_n or_o the_o spring_n of_o the_o air_n or_o some_o other_o cause_n as_o the_o pressure_n of_o some_o other_o body_n quite_o distinct_a from_o air._n upon_o the_o general_a view_n of_o this_o hypothesis_n it_o seem_v very_o consonant_a to_o the_o mechanical_a principle_n for_o if_o there_o be_v on_o the_o differ_a part_n of_o the_o surface_n of_o a_o fluid_a body_n unequal_a pressure_n it_o be_v plain_a as_o well_o by_o the_o nature_n of_o the_o thing_n as_o by_o what_o have_v be_v demonstrate_v by_o archimedes_n and_o his_o commentator_n that_o the_o great_a force_n will_v prevail_v against_o the_o lesser_a and_o that_o that_o part_n of_o the_o water_n surface_n must_v give_v way_n where_o it_o be_v least_o press_v so_o that_o that_o wherein_o the_o hypothesis_n i_o venture_v to_o propose_v to_o you_o differ_v from_o that_o which_o i_o dissent_v from_o be_v not_o that_o i_o be_v less_o mechanical_a but_o partly_o in_o this_o that_o whereas_o the_o hypothesis_n i_o question_v suppose_v a_o necessity_n of_o the_o protrusion_n or_o impulse_n of_o the_o air_n i_o do_v not_o require_v that_o supposition_n but_o be_v more_o general_a reach_v to_o other_o way_n of_o procure_v the_o ascension_n of_o liquor_n without_o raise_v they_o by_o the_o impulse_n of_o the_o air_n and_o partly_o and_o indeed_o chief_o in_o that_o the_o hypothesis_n i_o decline_v make_v the_o cause_n of_o the_o ascension_n of_o liquor_n to_o be_v only_o the_o increase_a pressure_n of_o the_o air_n external_a to_o the_o pipe_n and_o i_o chief_o make_v it_o to_o depend_v upon_o the_o diminish_v pressure_n of_o the_o air_n within_o the_o pipe_n on_o the_o score_n of_o the_o expansion_n it_o be_v bring_v to_o by_o suction_n to_o proceed_v now_o to_o some_o experiment_n that_o i_o make_v in_o favour_n of_o this_o hypothesis_n i_o shall_v begin_v with_o that_o which_o follow_v we_o take_v a_o glass-pipe_n bend_a like_o a_o syphon_n but_o so_o that_o the_o short_a leg_n be_v as_o parallel_v to_o the_o long_a as_o we_o can_v get_v it_o make_v and_o be_v hermetical_o seal_v at_o the_o end_n into_o this_o syphon_n we_o make_v a_o shift_n for_o it_o be_v not_o very_o easy_a to_o convey_v water_n so_o that_o the_o crooked_a part_n be_v hold_v downward_o the_o liquor_n reach_v to_o the_o same_o height_n in_o both_o the_o leg_n and_o yet_o there_o be_v about_o a_o inch_n and_o half_a of_o uncomprest_a air_n shut_v up_o in_o the_o short_a leg_n this_o little_a instrument_n for_o it_o be_v but_o about_o fifteen_o inch_n long_o be_v thus_o prepare_v it_o be_v plain_a that_o according_a to_o the_o hypothesis_n i_o dissent_v from_o there_o be_v no_o reason_n why_o the_o water_n shall_v ascend_v upon_o suction_n for_o though_o we_o shall_v admit_v that_o the_o external_a air_n be_v considerable_o compress_v or_o receive_v a_o notable_a impulse_n when_o the_o sucker_n chest_n be_v enlarge_v yet_o in_o our_o case_n that_o compression_n or_o protrusion_n will_v not_o reach_v the_o surface_n of_o the_o water_n in_o the_o short_a leg_n because_o it_o be_v there_o fence_v from_o the_o action_n of_o the_o external_a air_n by_o the_o side_n of_o the_o glass_n and_o the_o hermetical_a seal_n at_o the_o top_n and_o yet_o if_o one_o suck_v strong_o at_o the_o open_a orifice_n in_o the_o long_a leg_n the_o water_n in_o the_o short_a will_v be_v depress_v and_o that_o in_o the_o long_o ascend_v at_o one_o suck_v about_o a_o inch_n and_o half_a of_o which_o the_o reason_n be_v clear_a in_o our_o hypothesis_n for_o the_o spring_n of_o the_o include_v air_n together_o with_o the_o weight_n of_o the_o water_n in_o the_o short_a leg_n and_o the_o pressure_n of_o the_o atmospherical_a air_n assist_v by_o the_o weight_n of_o the_o liquor_n in_o the_o long_a leg_n counterbalanced_n one_o another_o before_o the_o suction_n begin_v but_o when_o afterward_o upon_o suction_n the_o air_n in_o the_o long_a leg_n come_v to_o be_v dilate_v and_o thereby_o weaken_a it_o be_v render_v unable_a to_o resist_v the_o undiminish_a pressure_n of_o the_o air_n include_v in_o the_o short_a leg_n which_o consequent_o expand_v itself_o by_o virtue_n of_o its_o elasticity_n depress_v the_o contiguous_a water_n and_o make_v it_o proportionable_o rise_v in_o the_o
our_o case_n there_o ought_v to_o be_v a_o great_a deal_n of_o difference_n between_o the_o operation_n of_o the_o spring_n of_o the_o include_v air_n and_o the_o weight_n of_o the_o atmosphere_n after_o suction_n have_v be_v once_o begin_v for_o the_o weight_n of_o the_o atmosphere_n that_o impel_v up_o mercury_n and_o other_o liquor_n when_o the_o suction_n be_v make_v in_o the_o open_a air_n continue_v still_o the_o same_o but_o the_o force_n or_o pressure_n of_o the_o include_v air_n be_v equal_a to_o the_o counterpressure_n of_o the_o mercury_n no_o long_o than_o the_o first_o moment_n of_o the_o suction_n after_o which_o the_o force_n of_o the_o imprison_a air_n still_o decrease_v more_o and_o more_o since_o this_o compress_a air_n be_v further_a and_o further_o expanded_a must_v needs_o have_v its_o spring_n proportionable_o weaken_a so_o that_o it_o need_v be_v no_o wonder_n that_o the_o mercury_n be_v not_o suck_v up_o any_o more_o than_o we_o have_v relate_v for_o there_o be_v nothing_o to_o make_v it_o ascend_v to_o a_o great_a height_n than_o that_o at_o which_o the_o debilitate_a spring_n of_o the_o include_v but_o expanded_a air_n be_v bring_v to_o a_o equipollency_n with_o the_o undiminish_a and_o indeed_o somewhat_o increase_v weight_n of_o the_o mercurial_a cylinder_n in_o the_o long_a leg_n and_o the_o pressure_n of_o the_o aerial_a cylinder_n in_o the_o same_o leg_n lessen_v by_o the_o action_n of_o he_o that_o suck_v for_o whereas_o when_o the_o orifice_n of_o this_o leg_n stand_v open_a the_o mercury_n be_v press_v on_o by_o a_o cylinder_n of_o the_o atmospherical_a air_n equivalent_a to_o about_o thirty_o inch_n of_o quicksilver_n by_o the_o mouth_n and_o action_n of_o he_o that_o suck_v the_o tube_n be_v free_v from_o the_o external_a air_n and_o by_o the_o dilatation_n of_o his_o thorax_n the_o neighbour_a air_n that_o have_v a_o free_a passage_n through_o his_o windpipe_n to_o it_o be_v proportionable_o expanded_a and_o have_v its_o spring_n and_o pressure_n weaken_a by_o which_o mean_n the_o compress_a air_n in_o the_o short_a leg_n of_o the_o syphon_n be_v enable_v to_o impel_v up_o the_o mercury_n till_o the_o late_o mention_v equilibrium_n or_o equipollency_n be_v attain_v and_o i_o must_v here_o take_v notice_n that_o as_o the_o quicksilver_n be_v raise_v by_o suction_n but_o a_o little_a way_n so_o the_o cylinder_n that_o be_v raise_v be_v a_o very_a long_a one_o whereas_o when_o mercury_n be_v suck_v up_o in_o the_o free_a air_n it_o be_v seldom_o raise_v to_o half_a that_o length_n though_o as_o i_o note_v before_o the_o impellent_fw-fr cause_n which_o be_v the_o weight_n of_o the_o atmosphere_n continue_v still_o the_o same_o whereas_o in_o our_o syphon_n when_o the_o mercury_n be_v suck_v up_o but_o a_o inch_n the_o compress_a air_n possess_v double_a the_o space_n it_o do_v before_o have_v by_o this_o expansion_n already_o lose_v a_o very_a considerable_a part_n of_o its_o former_a spring_n and_o pressure_n i_o shall_v here_o conclude_v this_o discourse_n but_o that_o i_o remember_v a_o phaenomenon_n of_o our_o pneumatic_a engine_n which_o to_o divers_a learned_a man_n especial_o aristotelian_o seem_v so_o much_o to_o argue_v that_o suction_n be_v make_v either_o by_o a_o fuga_fw-la vacui_fw-la or_o some_o internal_a principle_n that_o divers_a year_n ago_o i_o think_v fit_a to_o set_v down_o another_o account_n of_o it_o and_o late_o meet_v with_o that_o account_n among_o other_o paper_n i_o shall_v subjoin_v it_o just_a as_o i_o find_v it_o by_o way_n of_o appendix_n to_o the_o forego_n tract_n among_o the_o more_o familiar_a phaenomena_n of_o the_o machina_fw-la boyliana_n as_o they_o now_o call_v it_o none_o leave_v so_o much_o scruple_n in_o the_o mind_n of_o some_o sort_n of_o man_n as_o this_o that_o when_o one_o finger_n be_v lay_v close_o upon_o the_o orifice_n of_o the_o little_a pipe_n by_o which_o the_o air_n be_v wont_a to_o pass_v from_o the_o receiver_n into_o the_o exhaust_a cylinder_n the_o pulp_n of_o the_o finger_n be_v make_v to_o enter_v a_o good_a way_n into_o the_o cavity_n of_o the_o pipe_n which_o do_v not_o happen_v without_o a_o considerable_a sense_n of_o pain_n in_o the_o low_a part_n of_o the_o finger_n for_o most_o of_o those_o that_o be_v stranger_n to_o hydrostaticks_n especial_o if_o they_o be_v prepossess_v with_o the_o opinion_n general_o receive_v both_o in_o the_o peripatetic_a and_o other_o school_n persuade_v themselves_o that_o they_o feel_v the_o new_o mention_v and_o painful_a protuberance_n of_o the_o pulp_n of_o the_o finger_n to_o be_v effect_v not_o by_o pressure_n as_o we_o will_v have_v it_o but_o distinct_o by_o attraction_n to_o this_o we_o be_v wont_n to_o answer_v that_o common_a air_n be_v a_o body_n not_o devoid_a of_o weight_n the_o phenomenon_n be_v clear_o explicable_a by_o the_o pressure_n of_o it_o for_o when_o the_o finger_n be_v first_o lay_v upon_o the_o orifice_n of_o the_o pipe_n no_o pain_n nor_o swell_a be_v produce_v because_o the_o air_n which_o be_v in_o the_o pipe_n press_v as_o well_o against_o that_o part_n of_o the_o finger_n which_o cover_v the_o orifice_n as_o the_o ambient_fw-la air_n do_v against_o the_o other_o part_n of_o the_o same_o finger_n but_o when_o by_o pump_v the_o air_n in_o the_o pipe_n or_o the_o most_o part_n of_o it_o be_v make_v to_o pass_v out_o of_o the_o pipe_n into_o the_o exhaust_a cylinder_n than_o there_o be_v nothing_o leave_v in_o the_o pipe_n who_o pressure_n can_v any_o thing_n near_o countervail_v the_o undiminish_a pressure_n of_o the_o external_a air_n on_o the_o other_o part_n of_o the_o finger_n and_o consequent_o that_o air_n thrust_v the_o most_o yield_a and_o fleshy_a part_n of_o the_o finger_n which_o be_v the_o pulp_n into_o that_o place_n where_o its_o pressure_n be_v unresisted_a that_o be_v into_o the_o cavity_n of_o the_o pipe_n where_o this_o forcible_a intrusion_n cause_v a_o pain_n in_o those_o tender_a part_n of_o the_o finger_n to_o give_v some_o visible_a illustration_n of_o what_o we_o have_v be_v say_v as_o well_o as_o for_o other_o purpose_n i_o think_v on_o the_o follow_a experiment_n we_o take_v a_o glass-pipe_n of_o a_o convenient_a length_n and_o open_a at_o both_o end_n who_o cavity_n be_v near_o about_o a_o inch_n in_o diameter_n such_o a_o determinate_a breadth_n be_v convenient_a though_o not_o necessary_a to_o one_o of_o the_o end_n of_o this_o pipe_n we_o cause_v to_o be_v firm_o tie_v on_o a_o piece_n of_o very_o fine_a bladder_n that_o have_v be_v ruffle_v and_o oil_v to_o make_v it_o both_o very_a limber_a and_o unapt_a to_o admit_v water_n and_o care_n be_v take_v that_o the_o piece_n of_o bladder_n tie_v on_o shall_v be_v large_a enough_o not_o only_o to_o cover_v the_o orifice_n but_o to_o hang_v loose_a somewhat_o beneath_o it_o this_o do_v we_o put_v the_o cover_a end_n of_o the_o pipe_n into_o a_o glass-body_n or_o cucurbit_n purposely_o make_v more_o than_o ordinary_o tall_a and_o the_o pipe_n be_v hold_v in_o such_o manner_n as_o that_o the_o end_n of_o it_o reach_v almost_o but_o not_o quite_o to_o the_o bottom_n of_o the_o glass-body_n we_o cause_v water_n to_o be_v pour_v both_o into_o this_o vessel_n and_o into_o the_o pipe_n at_o its_o upper_a orifice_n which_o be_v leave_v open_a that_o the_o water_n may_v ascend_v equal_o enough_o both_o without_o and_o within_o the_o pipe_n and_o when_o the_o glass-body_n be_v full_a of_o water_n and_o the_o same_o liquor_n be_v level_a to_o it_o or_o a_o little_a high_o within_o the_o pipe_n the_o bladder_n at_o the_o low_a orifice_n be_v keep_v plump_a because_o the_o water_n within_o the_o pipe_n do_v by_o its_o weight_n press_v as_o forcible_o downward_o as_o the_o external_a water_n in_o the_o large_a glass_n endeavour_v to_o press_v it_o inward_o and_o upward_o all_o this_o be_v do_v we_o cause_v part_n of_o the_o water_n in_o the_o pipe_n to_o be_v take_v out_o of_o it_o which_o may_v be_v do_v either_o by_o put_v in_o and_o draw_v out_o a_o piece_n of_o sponge_n or_o of_o linen_n or_o more_o expeditious_o by_o suck_v up_o part_n of_o the_o water_n with_o a_o small_a pipe_n to_o be_v immediate_o after_o lay_v aside_o upon_o which_o removal_n of_o part_n of_o the_o internal_a water_n that_o which_o remain_v in_o the_o pipe_n be_v no_o long_o able_a by_o reason_n of_o its_o want_n of_o weight_n to_o press_v against_o the_o inside_n of_o the_o bladder_n near_o as_o forcible_o as_o it_o do_v before_o the_o external_a water_n who_o weight_n be_v not_o lessen_v press_v the_o side_n and_o bottom_n of_o the_o bladder_n whereto_o it_o be_v contiguous_a into_o the_o cavity_n of_o the_o pipe_n and_o thru_v it_o up_o therein_o so_o strong_o that_o the_o distend_v bladder_n make_v a_o kind_n of_o either_o thimble_n