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the_o other_o and_o there_o a_o little_a door_n may_v be_v make_v to_o open_v and_o shut_v at_o pleasure_n it_o be_v observe_v that_o by_o long_o tarry_v under_o the_o water_n in_o the_o bell_n the_o air_n become_v gross_a and_o misty_a which_o hinder_v a_o man_n from_o see_v about_o he_o the_o cause_n of_o this_o be_v vapour_n that_o come_v from_o the_o stomach_n lung_n and_o other_o part_n of_o the_o body_n especial_o from_o the_o stomach_n when_o the_o ventricle_n be_v full_a of_o meat_n it_o be_v not_o fit_a then_o that_o a_o man_n about_o to_o dive_v shall_v eat_v too_o much_o or_o drink_v too_o much_o especial_o such_o liquor_n as_o sack_n or_o brandy_n that_o beget_v many_o fume_n and_o vapour_n if_o a_o man_n be_v necessitate_v to_o tarry_v a_o pretty_a while_n below_o fresh_a air_n may_v be_v send_v down_o from_o above_o in_o bottle_n or_o bladder_n even_o as_o much_o as_o may_v fill_v up_o the_o place_n desert_v by_o the_o contract_v air._n it_o be_v observe_v by_o some_o that_o have_v be_v under_o the_o water_n that_o their_o ear_n have_v be_v so_o trouble_v that_o for_o a_o long_a time_n they_o have_v find_v difficulty_n to_o hear_v distinct_o the_o reason_n of_o this_o must_v be_v from_o the_o great_a pressure_n the_o tympanum_fw-la have_v suffer_v from_o the_o imprison_a air_n of_o the_o bell._n the_o organ_n of_o hear_v be_v soon_o trouble_v especial_o when_o a_o man_n be_v near_o to_o a_o great_a gun_n when_o it_o be_v fire_v and_o sure_o when_o a_o man_n be_v but_o 34_o foot_n down_o the_o air_n within_o the_o ark_n will_v be_v of_o double_a bensil_n put_v the_o case_n the_o man_n go_v down_o 68_o foot_n or_o 13_o or_o 14_o fathom_n the_o bensil_n be_v tripled_a that_o be_v to_o say_v if_o the_o air_n above_o have_v five_o degree_n of_o pressure_n in_o it_o the_o air_n of_o the_o bell_n at_o 68_o foot_n deep_a will_v have_v 15_o degree_n of_o pressure_n therefore_o the_o tympanum_fw-la of_o the_o ear_n that_o be_v but_o a_o small_a and_o thin_a membran_n must_v be_v sore_o distress_v that_o be_v overbended_a and_o press_v inward_a even_o as_o while_o a_o man_n set_v upon_o a_o drum_n head_n a_o great_a weight_n v_o g._n a_o bullet_n of_o lead_n or_o iron_n of_o 20_o or_o 30_o pound_n the_o skin_n by_o this_o suffer_v a_o extraordinary_a pressure_n whereby_o it_o be_v in_o hazard_n to_o be_v rend_v it_o be_v probable_a if_o a_o man_n shall_v go_v very_o far_o down_o the_o tympanum_fw-la may_v be_v in_o hazard_n of_o break_v or_o be_v rend_v in_o two_o piece_n there_o be_v a_o great_a pressure_n upon_o the_o one_o side_n from_o the_o air_n without_o than_o upon_o the_o other_o side_n from_o the_o internal_a air_n within_o which_o be_v think_v to_o be_v within_o the_o tympanum_fw-la there_o remain_v another_o phenomenon_n to_o be_v explicate_v and_o it_o be_v this_o the_o further_a up_o the_o ark_n come_v from_o the_o ground_n of_o the_o water_n towards_o the_o top_n the_o water_n within_o it_o subside_n and_o settle_v down_o 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the_o cold_a be_v the_o great_a if_o this_o be_v then_o far_o more_o air_n must_v be_v contract_v in_o go_v down_o from_o 10_o to_o 15_o fathom_n than_o in_o pass_v from_o 5_o to_o 10_o see_v as_o they_o say_v the_o further_o down_o the_o cold_a be_v the_o great_a and_o therefore_o the_o contraction_n of_o the_o air_n must_v be_v the_o great_a that_o be_v to_o say_v there_o must_v be_v more_o quantity_n of_o air_n contract_v in_o the_o one_o space_n than_o in_o the_o other_o but_o so_o it_o be_v that_o the_o further_o down_o the_o contraction_n be_v the_o less_o they_o judge_v likewise_o the_o coldness_n of_o the_o water_n to_o be_v the_o cause_n why_o the_o side_n of_o empty_a vessel_n be_v break_v in_o go_v down_o but_o if_o this_o be_v than_o a_o strong_a vessel_n shall_v go_v no_o further_o down_o than_o a_o weak_a vessel_n see_v cold_a can_v pierce_v through_o the_o side_n of_o the_o one_o as_o well_o as_o through_o the_o side_n of_o the_o other_o and_o why_o be_v it_o that_o a_o bladder_n full_a of_o wind_n will_v go_v down_o 40_o or_o 50_o fathom_n without_o burst_v yea_o 100_o and_o yet_o a_o stone-bottle_n or_o glass-bottle_n can_v go_v beyond_o 20_o or_o 30_o if_o cold_a have_v in_o it_o that_o power_n to_o break_v the_o side_n of_o a_o strong_a bottle_n it_o must_v be_v far_o more_o able_a to_o burst_v the_o side_n of_o a_o thin_a bladder_n this_o difference_n be_v clear_o explicate_v from_o the_o pressure_n of_o the_o water_n but_o i_o defy_v any_o man_n to_o show_v the_o difference_n from_o the_o coldness_n of_o it_o it_o be_v to_o be_v observe_v that_o in_o all_o such_o experiment_n of_o sink_v of_o vessel_n as_o hogshead_n barrel_n and_o bottle_n they_o must_v be_v close_o on_o all_o side_n therefore_o if_o a_o man_n desire_v to_o know_v how_o far_o down_o a_o glass-bottle_n be_v able_a to_o go_v without_o burst_v he_o must_v stop_v the_o mouth_n of_o it_o exact_o with_o a_o piece_n of_o wood_n and_o cement_n in_o set_v down_o the_o dimension_n of_o the_o ark_n i_o have_v restrict_v they_o to_o 40_o inch_n high_a and_o 36_o inch_n wide_a but_o if_o any_o man_n be_v desirous_a to_o enlarge_v they_o or_o make_v they_o less_o he_o may_v do_v it_o only_o it_o be_v to_o be_v observe_v that_o the_o large_a the_o ark_n be_v the_o footstool_n that_o sink_v it_o must_v be_v the_o heavy_a yet_o it_o have_v this_o advantage_n that_o it_o contain_v much_o air_n which_o be_v the_o great_a perfection_n of_o it_o one_o of_o a_o lesser_a size_n have_v this_o advantage_n that_o it_o be_v more_o tractable_a and_o easy_a to_o let_v down_o and_o to_o be_v pull_v up_o but_o these_o thing_n be_v best_a know_v from_o experience_n or_o if_o a_o man_n please_v he_o may_v calculate_v as_o the_o ark_n be_v a_o most_o useful_a device_n for_o profit_n so_o it_o be_v excellent_a for_o pleasure_n and_o recreation_n if_o a_o man_n be_v dispose_v to_o see_v the_o ground_n and_o channel_n of_o deep_a water_n or_o be_v incline_v to_o find_v out_o hydrostatical_a conclusion_n a_o knowledge_n very_o profitable_a and_o which_o few_o have_v attain_v to_o though_o it_o seem_v somewhat_o difficult_a to_o enter_v the_o ark_n and_o go_v down_o below_o the_o water_n yet_o a_o little_a use_n will_v expel_v all_o fear_n then_o a_o man_n may_v go_v down_o with_o less_o hazard_n and_o fear_v in_o the_o ark_n then_o in_o the_o bell_n because_o he_o may_v convenient_o fasten_v his_o hand_n to_o each_o side_n of_o the_o ark_n if_o need_n be_v he_o may_v convenient_o sit_v as_o in_o a_o chair_n all_o the_o time_n of_o down_o go_v and_o up-coming_a by_o fix_v a_o
his_o own_o opinion_n and_o shall_v be_v satisfy_v to_o enjoy_v my_o own_o till_o these_o of_o more_o experience_n convince_v i_o of_o the_o contrary_n there_o be_v some_o other_o thing_n far_a to_o be_v remark_v about_o the_o dipp_n and_o rise_v of_o coal_n which_o possible_o every_o one_o have_v not_o see_v they_o be_v so_o very_o rare_a and_o therefore_o be_v not_o fit_a here_o to_o be_v pass_v without_o be_v consider_v one_o be_v of_o a_o coal_n which_o have_v that_o contrary_a dipp_n and_o rise_v whereof_o i_o have_v be_v speak_v in_o one_o of_o the_o crop_n have_v not_o come_v out_o to_o the_o grass_n and_o terminat_fw-la but_o after_o it_o have_v rise_v a_o considerable_a way_n in_o its_o contrary_a course_n in_o stead_n of_o crop_v out_o have_v take_v a_o dipp_n towards_o the_o same_o point_n to_o which_o it_o dip_v first_o and_o so_o have_v dip_v to_o the_o centre_n of_o its_o course_n it_o have_v rise_v again_o and_o crop_v to_o the_o contrary_a point_n as_o be_v to_o be_v see_v in_o this_o eight_o figure_n figure_n 8._o where_o ab_fw-la be_v the_o surface_n of_o the_o earth_n the_o point_n b_o be_v the_o cropp_n of_o a_o coal_n dip_v from_o nw_n to_o the_o se._n from_o c_z it_o take_v its_o rise_n and_o course_n to_o a_o contrary_a cropp_n towards_o the_o point_n f_o where_o the_o dead_a cropp_n ought_v to_o be_v find_v but_o in_o stead_n of_o go_v that_o length_n it_o take_v another_o course_n from_o the_o point_n e_o dip_v se_n towards_o d_o from_o which_o it_o take_v its_o rise_n and_o continue_v it_o to_o the_o point_n a_o where_o it_o terminat_n and_o where_o the_o dead_a cropp_n be_v find_v i_o grant_v that_o it_o meet_v with_o a_o trouble_n or_o gay_a at_o the_o point_n e_o which_o seem_v to_o be_v the_o cause_n why_o its_o natural_a course_n be_v change_v but_o it_o be_v very_o extraordinary_a to_o see_v such_o a_o effect_n but_o of_o this_o afterward_o in_o its_o own_o place_n there_o be_v yet_o another_o thing_n to_o be_v remark_v in_o the_o dipp_n and_o rise_n of_o coal_n which_o be_v this_o in_o the_o most_o part_n of_o coal_n that_o have_v their_o course_n from_o dipp_n to_o crop_n without_o the_o intervention_n of_o a_o dyke_n or_o gay_n the_o declination_n be_v straight_o down_o from_o the_o horizontal_a line_n draw_v from_o the_o point_n of_o the_o crop_n to_o the_o far_a point_n of_o the_o dipp_n that_o be_v the_o coal_n decline_v from_o that_o point_n in_o a_o right_a line_n make_v with_o the_o horizontal_a line_n a_o right_n line_v angle_n angulus_fw-la rectilineus_fw-la though_o in_o some_o the_o angle_n be_v more_o acute_a and_o in_o other_o less_o as_o be_v to_o be_v see_v in_o the_o first_o and_o second_o figure_n where_o ab_fw-la be_v the_o horizontal_a line_n and_o b_o the_o crop_n bc_n be_v the_o body_n of_o the_o coal_n decline_v which_o meet_v with_o ab_fw-la in_o the_o point_n b_o constitute_v a_o right_o line_v angle_n and_o where_o abc_n in_o the_o second_o figure_n be_v a_o great_a angle_n than_o abc_n in_o the_o first_o yet_o i_o have_v see_v a_o coal_n the_o body_n whereof_o from_o the_o dipp_n or_o far_a point_n of_o declination_n have_v its_o rise_n towards_o the_o crop_n very_o insensible_o it_o be_v flat_a and_o then_o begin_v to_o be_v more_o sensible_a till_o at_o last_o come_v near_o to_o the_o surface_n of_o the_o earth_n it_o take_v in_o a_o sudden_a such_o a_o rise_n that_o from_o decline_v one_o foot_n of_o 12_o or_o 14_o it_o decline_v now_o one_o foot_n of_o three_o as_o may_v be_v make_v evident_a from_o this_o follow_a figure_n figure_n 9_o where_o ab_fw-la be_v the_o line_n draw_v from_o the_o extreme_a point_n of_o the_o cropp_n right_a horizontal_a the_o body_n of_o the_o coal_n rise_v insensible_o be_v dc_o but_o assoon_o as_o it_o come_v to_o c_o it_o rise_v with_o a_o great_a ascent_n till_o it_o cropp_n out_o at_o a._n here_o you_o see_v that_o in_o stead_n of_o one_o side_n of_o a_o triangle_n which_o the_o course_n of_o other_o coal_n in_o their_o rise_n or_o in_o their_o declination_n make_v this_o coal_n in_o rise_v make_v two_o side_n namely_o dc_o and_o ca_n the_o figure_n dbca_n be_v quadrilateral_a the_o coal_n of_o this_o course_n be_v real_o wrought_v and_o be_v yet_o visible_a in_o its_o waste_n where_o there_o be_v find_v no_o gay_a or_o dyke_n to_o make_v this_o alteration_n these_o be_v the_o chief_a thing_n that_o i_o have_v think_v worthy_a of_o observation_n in_o the_o dipp_n and_o rise_n of_o coal_n and_o therefore_o i_o come_v now_o to_o touch_v a_o little_a the_o other_o part_n of_o their_o course_n which_o be_v common_o term_v the_o streek_a of_o a_o coal_n to_o make_v intelligible_a to_o those_o who_o be_v not_o experimental_o acquaint_v with_o coal_n this_o term_n or_o what_o the_o streek_a be_v we_o must_v lay_v this_o foundation_n that_o the_o coal_n be_v a_o physical_a body_n and_o so_o have_v its_o three_o principal_a dimension_n which_o do_v constitute_v it_o so_o viz_o longitude_n latitude_n and_o profundity_n it_o be_v latitude_n be_v that_o part_n contain_v between_o its_o extreme_a line_n which_o be_v measurable_a by_o its_o surface_n to_o which_o its_o dip_v and_o rise_v though_o always_o incident_a yet_o be_v but_o accidental_a it_o be_v profundity_n be_v to_o be_v measure_v by_o the_o distance_n between_o the_o two_o surface_n immediate_o next_o to_o it_o above_z and_o below_o which_o be_v term_v in_o coallery_n its_o roof_n and_o pavement_n because_o of_o the_o resemblance_n they_o have_v to_o the_o roof_n and_o pavement_n of_o a_o house_n the_o longitude_n be_v nothing_o else_o but_o what_o be_v term_v by_o the_o coal-hewers_a the_o streek_a for_o if_o you_o imagine_v a_o line_n draw_v along_o the_o extreme_a point_n of_o the_o rise_v or_o cropp_n of_o the_o coal_n that_o be_v proper_o the_o streek_a of_o the_o coal_n there_o be_v but_o few_o thing_n to_o be_v remark_v as_o to_o this_o part_n of_o coal_n only_a first_o to_o find_v how_o it_o lie_v to_o what_o point_v of_o the_o compass_n it_o move_v for_o know_v whereof_o there_o be_v this_o general_a rule_n that_o have_v find_v your_o dipp_n and_o rise_v to_o what_o ever_o point_v that_o course_n be_v direct_v the_o streek_a be_v to_o the_o quite_o contrary_a for_o suppose_v a_o coal_n dipp_n se_n the_o two_o point_n that_o respect_v the_o dipp_n and_o rise_v must_v be_v se_n and_o nw_n be_v the_o point_v opposite_a one_o to_o another_o then_o it_o must_v needs_o follow_v that_o the_o streek_n must_v run_v sweet_z and_o ne_fw-fr which_o two_o course_n divide_v the_o compass_n at_o right_a angle_n and_o therefore_o where_o a_o coal_n be_v find_v to_o have_v contrary_a dipp_n and_o rise_n they_o decline_v sometime_o to_o all_o the_o point_n of_o the_o compass_n whereof_o there_o have_v be_v give_v two_o notable_a instance_n before_o it_o must_v needs_o follow_v that_o there_o be_v also_o contrary_a streeks_n and_o so_o the_o streek_a of_o a_o body_n of_o coal_n be_v sometime_o find_v to_o describe_v a_o round_a figure_n though_o not_o perfect_o circular_a and_o sometime_o a_o multangular_a figure_n for_o it_o can_v be_v suppose_v that_o the_o streek_a make_v always_o a_o right_a line_n between_o the_o two_o point_n from_o which_o it_o be_v reckon_v for_o example_n between_o the_o laird_n of_o prestongrange_n his_o house_n at_o preston-pan_n and_o the_o stobhill_n there_o be_v the_o streeks_n of_o several_a coal_n lie_v one_o above_o another_o which_o will_v be_v of_o length_n about_o seven_o or_o eight_o mile_n lie_v near_o upon_o sweet_z and_o ne_fw-fr yet_o the_o crop_n of_o the_o say_a coal_n their_o dipp_n and_o rise_v be_v nw_n and_o se_n be_v sometime_o far_o advance_v towards_o the_o se_n sometime_o far_o back_o towards_o the_o nw_n by_o the_o difference_n of_o a_o mile_n and_o this_o general_o occasion_v by_o the_o encounter_n of_o a_o dyke_n or_o gae_n whereof_o hereafter_o the_o same_o question_n that_o occure_v in_o the_o coal_n dip_v towards_o a_o hill_n on_o rise_v above_o ground_n come_v to_o be_v inquire_v into_o here_o viz._n if_o a_o coal_n encounter_v amascent_fw-la or_o brae_n above_o ground_n in_o its_o streek_n rise_v also_o with_o the_o ground_n and_o keep_v its_o ascent_n i_o answer_v i_o have_v find_v it_o so_o in_o all_o the_o coal_n i_o have_v ever_o see_v of_o that_o nature_n god_n in_o his_o providence_n have_v so_o order_v it_o that_o thereby_o it_o may_v be_v the_o more_o useful_a in_o regard_n more_o thereof_o may_v be_v wrought_v by_o one_o level_n or_o aquaduct_n by_o which_o the_o water_n be_v convey_v away_o as_o afterward_o will_v be_v observe_v in_o speak_v to_o level_n for_o confirmation_n whereof_o i_o shall_v bring_v instance_n both_o of_o
they_o do_v not_o counter_a poise_n one_o another_o according_a to_o their_o thickness_n for_o though_o the_o one_o pillar_n of_o water_n be_v ten_o time_n thick_a than_o the_o other_o and_o consequent_o heavy_a yet_o be_v it_o not_o able_a to_o press_v up_o the_o other_o that_o be_v more_o slender_a and_o so_o light_a beyond_o its_o own_o height_n and_o therefore_o they_o weigh_v only_o according_a to_o their_o altitude_n theorem_fw-la v._o in_o all_o fluid_n there_o be_v a_o pressure_n figure_n 1._o this_o be_v true_a not_o only_o of_o the_o element_n of_o air_n and_o water_n while_o they_o be_v out_o of_o their_o own_o place_n as_o they_o speak_v but_o while_o they_o be_v in_o it_o for_o air_n and_o water_n be_v natural_o endue_v with_o weight_n the_o second_o foot_n can_v be_v under_o the_o first_o unless_o it_o sustain_v it_o if_o this_o be_v it_o must_v necessary_o be_v press_v with_o its_o burden_n so_o this_o water_n be_v natural_o a_o heavy_a body_n the_o foot_n i_o can_v be_v under_o e_o unless_o it_o sustain_v it_o and_o be_v press_v with_o the_o burden_n of_o it_o the_o foot_n n_o be_v burden_v with_o they_o both_o from_o this_o pressure_n which_o be_v in_o air_n arise_v a_o certain_a sort_n of_o force_n and_o power_n which_o may_v be_v call_v bensil_n by_o virtue_n whereof_o a_o little_a quantity_n of_o air_n can_v expand_v and_o spread_v out_o itself_o to_o a_o very_a large_a quantity_n and_o may_v by_o extrinsic_a force_n be_v reduce_v to_o that_o small_a quantity_n again_o though_o this_o expansive_a faculty_n be_v evident_a in_o air_n yet_o it_o be_v scarce_o discernible_a in_o water_n unless_o it_o be_v in_o very_o deep_a part_n near_o the_o bottom_n where_o the_o pressure_n be_v great_a this_o pressure_n be_v not_o of_o the_o same_o degree_n in_o all_o the_o part_n but_o be_v increase_v and_o augment_v according_a to_o the_o deepness_n of_o the_o air_n and_o water_n for_o the_o air_n upon_o the_o top_n of_o mountain_n and_o high_a place_n be_v think_v to_o be_v of_o a_o less_o pressure_n then_o in_o valley_n and_o water_n be_v of_o a_o less_o pressure_n ten_o or_o twelve_o foot_n from_o the_o top_n than_o twenty_o or_o thirty_o so_o be_v the_o water_n n_o under_o a_o far_o less_o pressure_n than_o the_o water_n p_o or_o q._n theorem_fw-la vi_o the_o pressure_n of_o fluids_n be_v on_o every_o side_n figure_n 1._o the_o meaning_n be_v that_o air_n and_o water_n press_v not_o only_o downward_o but_o upward_o not_o to_o the_o right_a hand_n only_o but_o to_o the_o leave_v also_o and_o every_o way_n so_o the_o foot_n of_o water_n k_o not_o only_o press_v down_o the_o foot_n r_o but_o press_v up_o the_o foot_n f_o yea_o press_v the_o foot_n i_o and_o the_o foot_n l_o with_o the_o same_o weight_n and_o the_o first_o imaginary_a surface_n be_v as_o much_o press_v up_o by_o the_o water_n iklm_n as_o it_o be_v press_v down_o by_o the_o water_n efgh_n upon_o this_o account_n it_o be_v that_o when_o a_o sphere_n or_o glob_v be_v suspend_v in_o the_o middle_n of_o water_n or_o air_n all_o the_o point_n of_o their_o surface_n be_v uniform_o press_v after_o this_o manner_n be_v our_o body_n press_v with_o the_o environ_v air_n and_o the_o man_n that_o dive_v with_o the_o ambient_fw-la and_o environ_v water_n theorem_fw-la vii_o all_o the_o part_n of_o a_o fluid_a in_o the_o same_o horizontal_n line_n be_v equal_o press_v figure_n i._n the_o meaning_n be_v that_o the_o foot_n i_o be_v no_o more_o press_v than_o the_o foot_n k_o neither_o be_v the_o foot_n l_o more_o burden_v than_o the_o foot_n m._n the_o reason_n be_v because_o each_o of_o these_o foot_n sustain_v the_o same_o weight_n for_o efgh_a be_v all_o of_o they_o of_o the_o same_o burden_n therefore_o all_o the_o part_n of_o a_o fluid_a in_o the_o same_o horizontal_n surface_n be_v press_v most_o equal_o this_o hold_v true_a in_o air_n and_o mercury_n or_o in_o any_o other_o liquid_a also_o theorem_fw-la viii_o the_o pressure_n of_o fluids_n seem_v to_o 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inch_n sustain_v but_o two_o and_o the_o three_o but_o three_o but_o if_o the_o pressure_n be_v according_a to_o geometrical_a progression_n the_o three_o foot_n of_o water_n ought_v to_o sustain_v four_o inch_n of_o mercury_n the_o four_o eight_o the_o five_o sixteen_o etc._n etc._n which_o be_v contrary_a to_o experience_n theorem_fw-la ix_o in_o all_o fluid_n there_o be_v a_o twofold_a weight_n one_o sensible_a the_o other_o insensible_a the_o first_o be_v common_a to_o all_o heavy_a body_n which_o we_o find_v in_o water_n while_o we_o lift_v a_o vessel_n full_a of_o it_o from_o the_o ground_n the_o insensible_a weight_n of_o water_n and_o air_n or_o of_o any_o other_o fluid_a can_v scarce_o be_v discern_v by_o the_o sense_n though_o it_o be_v as_o real_a as_o the_o former_a because_o the_o pressure_n be_v uniform_a by_o virtue_n of_o the_o second_o bodies_z natural_o light_a than_o water_n be_v drive_v from_o the_o bottom_n to_o the_o top_n as_o cork_n so_o a_o man_n fall_v into_o a_o deep_a water_n go_v present_o to_o the_o bottom_n and_o instant_o come_v up_o again_o here_o be_v a_o natural_a effect_n which_o can_v want_v a_o natural_a cause_n and_o this_o can_v be_v nothing_o else_o but_o the_o pressure_n of_o the_o water_n by_o virtue_n whereof_o he_o come_v up_o and_o yet_o he_o find_v nothing_o drive_v he_o up_o or_o pull_v he_o up_o therefore_o there_o be_v in_o all_o fluid_a body_n a_o insensible_a weight_n as_o there_o be_v one_o sensible_a see_v the_o man_n that_o perhaps_o weigh_v seventeen_o stone_n be_v drive_v up_o fifteen_o or_o sixteen_o fathom_n by_o it_o and_o it_o must_v be_v very_o considerable_a and_o exceed_v the_o weight_n of_o the_o man_n see_v it_o be_v able_a to_o overcome_v such_o a_o weight_n so_o be_v vapour_n and_o smoke_n drive_v upward_o by_o the_o insensible_a weight_n of_o the_o air_n and_o by_o that_o same_o weight_n do_v the_o cloud_n swim_v above_o we_o theorem_fw-la x._o the_o insensible_a weight_n of_o fluids_n be_v only_o find_v by_o sense_n when_o the_o pressure_n be_v not_o uniform_a for_o understanding_n of_o this_o proposition_n i_o must_v suppose_v something_n that_o be_v possible_a but_o not_o practicable_a put_v the_o case_n then_o while_o a_o man_n open_v his_o hand_n the_o air_n below_o be_v remove_v he_o will_v scarce_o be_v able_a to_o sustain_v the_o weight_n of_o the_o air_n that_o rest_v upon_o the_o palm_n above_o or_o if_o the_o air_n above_o be_v annihilate_v he_o will_v not_o be_v able_a to_o bear_v down_o the_o weight_n that_o press_v upward_o or_o while_o a_o diver_n be_v in_o the_o bottom_n of_o the_o sea_n if_o it_o be_v possible_a to_o free_v any_o one_o part_n of_o his_o body_n from_o the_o pressure_n of_o the_o water_n suppose_v his_o right_a arm_n i_o doubt_v not_o but_o the_o blood_n will_v spring_v out_o in_o abundance_n from_o his_o finger-end_n for_o the_o arm_n be_v free_a and_o the_o other_o part_n extreme_o press_v the_o blood_n of_o necessity_n must_v be_v drive_v from_o the_o shoulder_n downward_o with_o force_n which_o can_v be_v without_o considerable_a pain_n it_o be_v evident_a also_o from_o the_o application_n of_o the_o cuppin-glass_n which_o be_v due_o apply_v to_o a_o man_n skin_n cause_v the_o air_n to_o press_v unequal_o the_o part_n without_o be_v more_o press_v than_o the_o part_n within_o in_o which_o case_n the_o unequal_a pressure_n cause_v the_o pain_n and_o so_o be_v find_v by_o sense_n theorem_fw-la xi_o a_o cylinder_n of_o water_n or_o of_o any_o other_o fluid_a body_n lose_v of_o its_o weight_n according_a to_o its_o reclination_n from_o a_o perpendicular_a position_n towards_o a_o horizontal_n or_o level_v situation_n for_o understanding_n of_o this_o consider_v that_o while_n a_o
pillar_n of_o mercury_n each_o one_o of_o they_o 29_o inch_n high_a it_o follow_v of_o necessity_n that_o the_o mercury_n within_o the_o tub_n must_v be_v as_o high_a as_o r._n it_o be_v no_o wonder_n to_o see_v the_o silver_n halt_v at_o r_o provide_v rx_n and_o zs_n be_v two_o bulk_n of_o mercury_n environ_v the_o pipe_n as_o the_o outward_a water_n environ_n the_o wide_a and_o narrow_a pipe_n neither_o aught_o any_o to_o wonder_v when_o the_o silver_n fall_v down_o and_o rest_v at_o r_o nothing_o environ_v the_o pipe_n but_o air_n see_v the_o pressure_n of_o the_o air_n be_v equivalent_a to_o the_o weight_n of_o 29_o inch_n of_o quicksilver_n this_o experiment_n be_v easy_o make_v take_v therefore_o a_o slender_a glass-pipe_n of_o any_o length_n beyond_o 30_o inch_n open_a at_o both_o end_n but_o the_o low_a end_n q_n must_v be_v draw_v so_o small_a by_o a_o flame_n of_o a_o lamp_n that_o the_o entry_n may_v be_v no_o wide_o than_o may_v admit_v the_o point_n of_o a_o small_a needle_n or_o the_o hair_n of_o one_o head_n then_o stop_v the_o say_a orifice_n pour_v in_o mercury_n above_o at_o the_o orifice_n n_o till_o the_o pipe_n be_v complete_o full_a next_o close_o the_o say_a orifice_n with_o wet_a paper_n and_o the_o pulp_n of_o your_o finger_n and_o open_v the_o low_a orifice_n you_o shall_v find_v which_o be_v very_o delightful_a to_o behold_v the_o mercury_n spring_v out_o like_v unto_o a_o small_a silver_n thread_n and_o fall_v down_o from_o the_o top_n n_o shall_v rest_v at_o r_o the_o motion_n cease_v at_o the_o narrow_a orifice_n q._n this_o show_v evident_o that_o there_o be_v not_o need_v always_o of_o stagnant_a mercury_n for_o try_v the_o torricellian_a experiment_n but_o only_o when_o the_o mouth_n of_o the_o pipe_n below_o be_v wide_a for_o be_v narrow_a the_o silver_n run_v slow_o out_o and_o consequent_o subside_v slow_o above_o and_o come_v down_o slow_o to_o r_o there_o rest_v but_o when_o the_o mouth_n be_v wide_o below_o the_o silver_n fall_v down_o so_o quick_o that_o it_o go_v beyond_o r_o before_o it_o can_v recover_v itself_o which_o recovery_n will_v never_o be_v unless_o there_o be_v stagnant_a mercury_n to_o run_v up_o again_o from_o what_o be_v say_v we_o see_v first_o that_o when_o one_o part_n of_o a_o surface_n of_o water_n or_o air_n be_v more_o burden_a than_o another_o the_o burden_a part_n present_o yield_v till_o it_o be_v no_o more_o burden_a than_o the_o other_o this_o be_v clear_a from_o the_o fall_n down_o of_o the_o water_n from_o e_z to_z g_z which_o can_v be_v support_v by_o the_o part_n i_o because_o more_o burden_a than_o the_o rest_n we_o see_v second_o that_o the_o element_n of_o air_n rest_v upon_o the_o surface_v of_o all_o body_n with_o a_o considerable_a weight_n otherwise_o it_o can_v not_o sustain_v the_o water_n before_o it_o fall_v down_o from_o e_z to_z g_z for_o if_o it_o do_v not_o rest_n upon_o the_o surface_n mh_o with_o weight_n the_o water_n can_v never_o be_v suspend_v see_v the_o application_n of_o the_o finger_n to_o the_o orifice_n e_o be_v only_o the_o accidental_a cause_n of_o this_o sustentation_n we_o see_v three_o that_o according_a to_o the_o difference_n of_o natural_a weight_n between_o two_o fluid_n so_o be_v the_o proportion_n of_o altitude_n between_o two_o of_o their_o cylinder_n therefore_o air_n be_v reckon_v 14000_o time_n light_a than_o mercury_n it_o follow_v that_o the_o cylinder_n of_o mercury_n sustain_v by_o the_o air_n must_v be_v 14000_o time_n low_o and_o short_a than_o the_o cylinder_n of_o air_n that_o sustain_v it_o which_o appear_v from_o this_o experiment_n to_o be_v true_a see_v by_o the_o pressure_n of_o the_o air_n which_o be_v think_v to_o be_v about_o 7000_o fathom_n high_a 29_o inch_n of_o mercury_n be_v support_v between_o r_o and_o x._o in_o a_o word_n if_o air_n be_v natural_o 14000_o time_n light_a than_o mercury_n which_o be_v very_o probable_a then_o must_v the_o altitude_n of_o it_o common_o call_v the_o atmosphere_n be_v fourteen_o thousand_o time_n nine_o and_o twenty_o inch_n that_o be_v 406000_o or_o of_o foot_n 33833._o experiment_n iii_o figure_n 6._o while_o the_o outward_a and_o inward_a water_n be_v of_o the_o same_o altitude_n withdraw_v the_o inward_a air_n eglantine_n by_o suction_n or_o by_o any_o other_o device_n you_o think_v fit_a and_o you_o will_v find_v the_o water_n rise_v as_o high_a as_o e_z which_o i_o suppose_v to_o be_v 34_o foot_n above_o mgh_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 fk_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 mh_o 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 mh_o 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 mh_o 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'it_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 dehk_v the_o second_o that_o be_v imaginary_a be_v li_z six_o foot_n below_o it_o the_o three_o of_o the_o same_o kind_n be_v mg_n six_o foot_n low_o the_o four_o be_v nfo_n six_o foot_n yet_o low_o the_o last_o and_o low_a be_v abc_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 da_fw-la 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 of_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 ef._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 hg_v 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 ki_v the_o internal_a water_n become_v no_o long_a than_o ki_v 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 no_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 no_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 gh_o 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_o gh_a 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 ki_v in_o this_o case_n the_o water_n within_o it_o become_v no_o long_o then_o ki_v the_o surface_n li_n 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 abc_n then_o in_o the_o next_o no_z and_o more_o in_o this_o then_o in_o the_o surface_n mg_n and_o more_o in_o this_o then_o in_o li._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 fluid_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
90_o inch_n will_v give_v 15_o foot_n but_o 15_o of_o water_n in_o height_n and_o six_o inch_n thick_a be_v the_o just_a weight_n of_o it_o in_o a_o balance_n viz._n 208_o pound_n we_o see_v second_o the_o broad_a and_o large_a the_o surface_n of_o a_o fluid_a be_v it_o be_v the_o more_o able_a and_o strong_a to_o support_v a_o heavy_a burden_n therefore_o the_o part_n of_o a_o surface_n of_o water_n six_o inch_n square_v every_o way_n will_v carry_v a_o far_o great_a weight_n than_o a_o part_n four_o inch_n square_a though_o a_o surface_n of_o water_n 34_o or_o 35_o foot_n deep_a be_v not_o able_a to_o sustain_v a_o cylinder_n of_o gold_n if_o it_o exceed_v 28_o or_o 29_o inch_n in_o height_n yet_o take_v a_o cylinder_n of_o gold_n 10_o foot_n high_a and_o reduce_v it_o by_o make_v it_o thick_a to_o the_o height_n of_o 20_o inch_n a_o surface_n of_o water_n little_o more_o than_o 24_o foot_n deep_o will_v sustain_v it_o or_o reduce_v a_o cylinder_n 10_o foot_n high_a which_o require_v a_o surface_n more_o than_o 100_o foot_n deep_a to_o a_o cylinder_n six_o inch_n high_a a_o surface_n little_o more_o than_o seven_o foot_n deep_o will_v support_v it_o we_o see_v three_o the_o reason_n why_o body_n that_o be_v broad_a and_o large_a move_v slowly_o through_o air_n and_o water_n than_o body_n that_o be_v more_o thin_a and_o slender_a though_o both_o be_v of_o the_o same_o weight_n in_o a_o balance_n for_o example_n 20_o pound_n of_o lead_n long_o and_o slender_a like_o a_o arrow_n will_v go_v soon_o to_o the_o ground_n of_o a_o deep_a water_n than_o a_o piece_n of_o lead_n of_o the_o same_o weight_n in_o form_n of_o a_o platter_n or_o bason_n the_o reason_n be_v because_o as_o the_o body_n be_v broad_a so_o it_o take_v a_o broad_a part_n of_o a_o surface_n which_o broad_a part_n be_v strong_a and_o able_a than_o a_o narrow_a part_n and_o so_o make_v the_o great_a resistance_n the_o same_o be_v the_o reason_n why_o a_o bullet_n six_o inch_n in_o diameter_n move_v slowly_a through_o the_o air_n shoot_v from_o a_o cannon_n than_o a_o bullet_n one_o inch_n in_o diameter_n for_o the_o same_o reason_n ship_n of_o seven_o or_o eight_o hundred_o tun_n move_v far_o slowly_o through_o the_o air_n and_o water_n than_o vessel_n of_o less_o burden_n item_n large_a and_o big_a fowl_n as_o eagle_n move_v slowly_o than_o small_a bird_n as_o swallow_n yea_o of_o fowl_n of_o the_o same_o quantity_n one_o may_v move_v quick_o than_o another_o as_o be_v evident_a in_o long-winged_a hawk_n as_o falcon_n that_o by_o the_o sharpness_n of_o their_o wing_n move_v far_o more_o space_n in_o half_a a_o hour_n than_o kite_n or_o gosehawk_n who_o wing_n be_v round_a we_o see_v four_a that_o there_o be_v no_o body_n how_o heavy_a soever_o but_o it_o may_v be_v support_v by_o the_o surface_n of_o a_o fluid_a either_o in_o air_n or_o in_o water_n i_o grant_v the_o strong_a surface_n of_o air_n that_o can_v be_v have_v be_v not_o able_a to_o support_v more_o weight_n than_o a_o cylinder_n of_o gold_n 28_o inch_n high_a yet_o though_o it_o be_v as_o large_a and_o broad_a as_o a_o millstone_n if_o it_o do_v not_o exceed_v the_o say_a height_n the_o air_n be_v able_a to_o sustain_v it_o for_o the_o same_o cause_n if_o it_o be_v possible_a to_o free_v a_o millstone_n of_o the_o air_n that_o rest_v upon_o it_o the_o air_n below_o will_v lift_v it_o from_o the_o ground_n and_o carry_v it_o up_o many_o fathom_n even_o till_o it_o come_v to_o a_o surface_n equal_a in_o power_n to_o the_o weight_n of_o the_o stone_n or_o if_o a_o large_a millstone_n be_v demit_v from_o the_o top_n of_o the_o atmosphere_n towards_o the_o earth_n it_o can_v hardly_o touch_v the_o ground_n be_v detain_v by_o the_o way_n by_o a_o surface_n counterpoise_v it_o or_o if_o it_o do_v touch_v through_o the_o swiftness_n of_o the_o motion_n it_o will_v sure_o as_o it_o be_v rebound_n and_o be_v carry_v up_o again_o it_o be_v always_o to_o be_v remember_v that_o in_o such_o trial_n the_o air_n be_v suppose_v not_o to_o follow_v or_o to_o be_v unite_v after_o the_o stone_n pass_v thorough_a now_o if_o the_o air_n be_v able_a to_o do_v this_o far_o more_o the_o water_n that_o be_v a_o body_n a_o thousand_o time_n heavy_a we_o see_v five_o the_o reason_n why_o heavy_a body_n move_v so_o easy_o through_o air_n and_o water_n namely_o because_o the_o part_n that_o be_v divide_v by_o the_o body_n that_o be_v move_v be_v present_o reunite_v and_o close_v again_o by_o which_o mean_v it_o be_v drive_v forward_o the_o pressure_n upon_o the_o back_n be_v as_o much_o as_o the_o pressure_n before_o if_o this_o be_v not_o no_o body_n whatsoever_o will_v be_v able_a to_o move_v itself_o one_o foot_n forward_o for_o example_n if_o when_o a_o man_n have_v advance_v one_o step_n forward_o the_o air_n do_v not_o close_o again_o upon_o his_o back_n the_o force_n of_o the_o air_n upon_o his_o belly_n and_o breast_n will_v not_o only_o stop_v he_o but_o violent_o thrust_v he_o backward_o 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further_o down_o and_o the_o light_a it_o be_v it_o sink_v the_o less_o for_o if_o cd_o be_v of_o gold_n it_o will_v go_v further_o down_o than_o be_v of_o brass_n or_o iron_n and_o if_o cd_o be_v a_o stone_n that_o be_v light_a in_o specie_fw-la than_o brass_n it_o will_v not_o go_v so_o far_o down_o this_o let_v we_o know_v the_o reason_n why_o thick_a black_a and_o heavy_a cloud_n come_v near_o to_o the_o earth_n than_o thin_a white_a and_o light_a we_o see_v ninthly_a that_o the_o pressure_n of_o the_o air_n be_v determinable_a even_o in_o its_o high_o degree_n and_o seem_v to_o be_v the_o same_o in_o all_o place_n of_o the_o world_n but_o the_o pressure_n of_o the_o water_n be_v not_o so_o the_o reason_n of_o the_o first_o part_n be_v because_o the_o element_n of_o air_n seem_v to_o be_v of_o the_o same_o height_n in_o all_o place_n and_o therefore_o we_o may_v know_v its_o outmost_a pressure_n which_o be_v just_o equivalent_a to_o the_o weight_n of_o 28_o or_o 29_o inch_n of_o 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represent_v a_o deep_a water_n who_o first_o and_o visible_a surface_n be_v fg._n the_o imaginary_a surface_n be_v elc_a 34_o foot_n below_o it_o adb_n be_v a_o siphon_n work_v below_o this_o water_n with_o mercury_n ael_n be_v a_o vessel_n with_o stagnant_a mercury_n among_o which_o the_o orifice_n a_o be_v drown_v the_o other_o orifice_n b_o exist_v among_o the_o water_n dm_o be_v the_o height_n of_o the_o siphon_n above_o the_o line_n of_o level_n which_o i_o suppose_v be_v 58_o inch_n for_o make_v it_o work_v stop_v the_o two_o orifice_n close_o and_o pour_v in_o as_o much_o mercury_n at_o a_o hole_n make_v at_o d_o as_o will_v fill_v both_o the_o leg_n then_o stop_v the_o say_a hole_n open_v the_o two_o orifice_n a_o and_o b_o and_o you_o will_v find_v the_o liquor_n run_v as_o long_o out_o at_o b_o as_o there_o be_v any_o almost_o in_o the_o vessel_n ael_n for_o evince_v this_o which_o be_v the_o only_a difficulty_n consider_v that_o if_o this_o siphon_n be_v fill_v with_o 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end_v but_o if_o the_o leg_n ad_fw-la be_v six_o time_n wide_a than_o bd_o the_o liquor_n will_v not_o run_v out_o at_o b._n i_o shall_v answer_v this_o in_o the_o close_a from_o this_o experiment_n we_o see_v first_o that_o the_o motion_n of_o fluid_a body_n up_o through_o pump_n and_o siphons_n be_v not_o for_o shune_v vacuity_n but_o because_o they_o be_v press_v up_o violent_o we_o see_v next_o that_o when_o the_o pressure_n be_v uniform_a there_o be_v no_o motion_n in_o fluids_n but_o assoon_o as_o one_o part_n be_v more_o press_v than_o another_o motion_n begin_v because_o this_o siphon_n will_v not_o operate_v if_o the_o orifice_n be_v make_v in_o c_o but_o if_o so_o be_v it_o be_v in_o d_o than_o the_o motion_n begin_v because_o there_o be_v here_o a_o unequal_a pressure_n which_o be_v not_o in_o the_o other_o we_o see_v three_o that_o fluids_n have_v a_o determinate_a sphere_n of_o activity_n to_o which_o they_o be_v able_a to_o press_v and_o no_o further_o because_o this_o water_n be_v not_o able_a to_o press_v mercury_n high_o than_o 58_o inch_n so_o the_o air_n can_v raise_v water_n high_o than_o 34_o foot_n if_o this_o water_n be_v 68_o foot_n deep_a the_o sphere_n of_o its_o activity_n will_v be_v 116_o inch_n we_o see_v four_a that_o in_o fluids_n there_o be_v a_o pondus_fw-la and_o a_o potentia_n and_o that_o the_o inequality_n of_o weight_n between_o the_o two_o be_v the_o only_a cause_n of_o motion_n we_o see_v five_o that_o as_o long_o as_o this_o inequality_n of_o weight_n continue_v as_o long_o continue_v the_o motion_n because_o as_o long_o as_o bd_o be_v heavy_a than_o ld_n the_o motion_n persevere_fw-la we_o see_v sixthly_a the_o possibility_n of_o a_o perpetual_a motion_n in_o fluids_n because_o the_o liquor_n run_v perpetual_o out_o at_o b._n if_o it_o be_v say_v the_o motion_n end_v when_o the_o stagnant_a mercury_n ael_n fail_v i_o answer_v this_o stop_n be_v only_o accidental_a and_o not_o essential_o from_o the_o nature_n of_o fluids_n if_o it_o be_v inquire_v whether_o or_o not_o will_v the_o mercury_n run_v out_o at_o b_o upon_o supposition_n the_o shank_n ld_n be_v twice_o as_o wide_o as_o the_o shank_n bd_o i_o answer_v it_o will_v if_o it_o be_v say_v that_o the_o one_o be_v far_o heavy_a than_o the_o other_o namely_o ld_n than_o db._n i_o answer_v weight_n in_o fluids_n be_v not_o count_v according_a to_o thickness_n but_o according_a to_o altitude_n experiment_n xx._n figure_n 27._o this_o last_o be_v for_o demonstrate_v the_o precise_a and_o just_a weight_n of_o any_o pillar_n of_o air_n water_n mercury_n or_o of_o any_o other_o fluid_a body_n if_o some_o of_o their_o dimension_n be_v but_o once_o know_v ab_fw-la then_o be_v a_o square_a pipe_n 12_o foot_n high_a and_o six_o inch_n in_o wideness_n full_a of_o water_n rest_v upon_o the_o surface_n of_o air_n ac_fw-la and_o eglantine_n be_v a_o square_a pipe_n 12_o foot_n high_a and_o 12_o inch_n wide_a full_a of_o water_n rest_v upon_o the_o surface_n of_o air_n ef._n none_o needs_o to_o doubt_v but_o the_o two_o water_n will_v be_v suspend_v after_o this_o manner_n even_o though_o the_o orifice_n a_o and_o e_o be_v downward_o especial_o if_o they_o be_v guard_v with_o water_n but_o the_o demonstration_n will_v be_v the_o more_o evident_a that_o we_o suppose_v the_o two_o pillar_n of_o water_n to_o be_v suspend_v as_o they_o be_v from_o this_o experiment_n i_o say_v first_o that_o the_o pillar_n of_o air_n cd_o be_v 168_o pound_n weight_n at_o least_o which_o i_o prove_v thus_o the_o water_n ab_fw-la be_v 168_o pound_n therefore_o the_o air_n cd_o must_v be_v as_o much_o i_o prove_v the_o antecedent_n because_o it_o be_v a_o pillar_n of_o water_n 12_o foot_n high_a and_o six_o inch_n thick_a but_o every_o half_a cubical_a foot_n of_o water_n that_o contain_v 216_o inch_n weigh_v seven_o pound_n therefore_o see_v the_o pillar_n be_v 12_o foot_n it_o must_v contain_v 24_o half_a foot_n but_o 24_o time_n 7_o be_v 168._o the_o only_a difficulty_n be_v to_o prove_v the_o connexion_n which_o i_o do_v thus_o from_o the_o seven_o theor._n all_o the_o part_n of_o a_o fluid_a in_o the_o same_o horizontal_n line_n be_v equal_o press_v but_o so_o it_o be_v that_o the_o part_n a_o and_o the_o part_n c_o be_v in_o the_o same_o horizontal_a surface_n therefore_o the_o part_n a_o and_o the_o part_n c_o be_v equal_o press_v but_o if_o the_o part_n a_o and_o the_o part_n c_o be_v equal_o press_v the_o pillar_n of_o air_n cd_o must_v be_v as_o heavy_a as_o the_o pillar_n of_o water_n ab_fw-la i_o say_v second_o that_o the_o pillar_n of_o air_n fh_o weigh_v 672_o pound_n i_o prove_v it_o thus_o
the_o water_n eglantine_n weigh_v 672_o pound_n therefore_o the_o air_n fh_v weigh_v as_o much_o the_o antecedent_n be_v clear_a because_o eglantine_n be_v a_o square_a pillar_n of_o water_n 12_o foot_n high_a and_o 12_o inch_n thick_a but_o every_o cubical_a foot_n of_o water_n weigh_v 56_o pound_n but_o 12_o time_n 56_o be_v 672._o i_o prove_v the_o connexion_n as_o before_o all_o the_o part_n of_o a_o horizontal_a surface_n be_v equal_o press_v therefore_o the_o part_n f_o must_v sustain_v as_o much_o burden_n as_o the_o part_n e._n to_o proceed_v a_o little_a further_o let_v we_o suppose_v the_o pipe_n ab_fw-la to_o be_v 34_o foot_n high_a and_o the_o pipe_n eglantine_n to_o be_v as_o much_o i_o assert_v then_o three_o the_o pillar_n of_o air_n cd_o to_o weigh_v 476_o pound_n which_o i_o prove_v as_o before_o all_o the_o part_n of_o the_o same_o surface_n be_v burden_v with_o the_o like_a weight_n but_o the_o part_n a_o sustain_v 476_o pound_n therefore_o the_o part_n c_o must_v support_v as_o much_o the_o connexion_n be_v evident_a and_o the_o antecedent_n be_v so_o too_o because_o the_o water_n ab_fw-la being_n 34_o foot_n high_a and_o six_o inch_n thick_a must_v weigh_v 476_o pound_n for_o if_o 216_o inch_n weigh_v seven_o pound_n 14688_o inch_n must_v weigh_v 476_o pound_n i_o assert_v four_a the_o pillar_n of_o air_n fh_o to_o weigh_v 1904_o pound_n which_o i_o demonstrat_fw-la by_o the_o former_a medium_fw-la all_o the_o part_n of_o a_o fluid_a that_o lie_n in_o the_o same_o horizontal_a surface_n be_v equal_o press_v but_o so_o it_o be_v that_z e_z and_o f_o do_v so_o lie_v therefore_o f_o must_v be_v as_o much_o burden_v as_o e_o the_o water_n therefore_o eglantine_n weigh_v 1904_o pound_n the_o air_n fh_v must_v weigh_v as_o much_o for_o if_o 216_o inch_n of_o water_n weigh_v seven_o pound_n 58752_o inch_n for_o so_o many_o be_v in_o the_o water_n eglantine_n must_v weigh_v 1904_o pound_n let_v we_o suppose_v second_o the_o tub_n ab_fw-la to_o be_v only_o 29_o inch_n high_a and_o the_o tub_n eglantine_n of_o the_o same_o height_n and_o that_o six_o inch_n wide_a and_o this_o 12_o inch_n wide_a i_o affirm_v then_o five_o the_o air_n cd_o to_o weigh_v yet_o 476_o pound_n and_o the_o air_n fh_v to_o weigh_v 1904_o pound_n because_o the_o pillar_n of_o mercury_n ab_fw-la weigh_v 476_o pound_n and_o the_o pillar_n of_o mercury_n eglantine_n weigh_v 1904_o pound_n therefore_o if_o ab_fw-la be_v 476_o cd_o must_v be_v as_o much_o and_o if_o eglantine_n be_v 1904_o fh_o must_v be_v of_o the_o same_o weight_n i_o prove_v the_o mercury_n ab_fw-la to_o weigh_v about_o 476_o pound_n though_o it_o be_v but_o 29_o inch_n high_a because_o it_o be_v 14_o time_n heavy_a than_o water_n for_o the_o same_o cause_n do_v the_o mercury_n eglantine_n weigh_v about_o 1904_o pound_n i_o say_v about_o because_o 34_o foot_n contain_v 29_o inch_n more_o than_o 14_o time_n let_v it_o be_v suppose_v three_o the_o pipe_n eglantine_n be_v 34_o foot_n high_a to_o have_v the_o one_o half_a of_o it_o ig_v full_a of_o air_n and_o the_o other_o half_o eke_o full_a of_o water_n i_o affirm_v then_o sixthly_a the_o part_n e_o and_o the_o part_n f_o to_o be_v yet_o equal_o burden_v that_o be_v to_o say_v the_o water_n eke_o that_o be_v now_o but_o 17_o foot_n make_v as_o great_a a_o pressure_n upon_o e_o as_o when_o it_o be_v 34_o foot_n the_o reason_n of_o this_o be_v sure_o the_o pressure_n of_o the_o air_n ig_n that_o bear_v down_o the_o water_n ke_n with_o the_o weight_n of_o 952_o pound_n the_o half_a of_o 1904_o pound_n if_o it_o be_v say_v according_a to_o the_o theorem_fw-la 21_o that_o there_o be_v as_o much_o pressure_n and_o weight_n in_o the_o least_o part_n of_o a_o fluid_a as_o in_o the_o whole_a therefore_o the_o air_n ig_n must_v be_v as_o heavy_a as_o eh_n i_o answer_v ig_n be_v not_o so_o heavy_a as_o fh_v because_o the_o water_n eke_o impend_v in_o the_o low_a part_n of_o the_o tub_n have_v occasion_v the_o air_n ig_n to_o expand_v itself_o so_o many_o inch_n by_o which_o mean_n it_o lose_v so_o many_o degree_n of_o its_o bensil_n if_o you_o remove_v the_o water_n eke_o then_o will_v the_o air_n ig_n be_v as_o heavy_a as_o fh_v because_o eke_o be_v air_n it_o reduce_v ig_a to_o that_o same_o degree_n of_o bensil_n with_o itself_o but_o when_o the_o air_n e_z be_v burden_v with_o the_o water_n eke_o it_o can_v make_v the_o air_n ig_n of_o that_o same_o weight_n with_o itself_o let_v we_o suppose_v four_a that_o only_o eight_o foot_n and_o a_o half_a of_o water_n be_v in_o the_o tub_n namely_o between_o e_z and_o n._n i_o say_v then_o seventhly_a that_o the_o part_n e_o be_v as_o much_o burden_v with_o it_o as_o when_o the_o pipe_n be_v full_a because_o the_o 25_o foot_n and_o a_o half_a of_o air_n ng_z be_v exact_o as_o heavy_a as_o the_o 25._o foot_n and_o a_o half_a of_o the_o water_n that_o be_v go_v i_o prove_v it_o thus_o the_o air_n e_z have_v the_o weight_n of_o 1904_o pound_n in_o itself_o see_v the_o weight_n of_o the_o surface_n be_v always_o equal_a to_o the_o weight_n of_o the_o pillar_n but_o be_v burden_v with_o the_o water_n en_fw-fr that_o weigh_v 476_o pound_n it_o can_v press_v up_o with_o more_o weight_n then_o with_o 1428_o pound_n and_o therefore_o the_o top_n of_o the_o water_n n_o must_v press_v upon_o the_o under_o part_n of_o the_o air_n that_o be_v contiguous_a with_o it_o with_o 1428._o if_o this_o be_v the_o air_n ng_z must_v press_v down_o with_o as_o much_o see_v according_a to_o the_o 20_o theorem_fw-la it_o be_v impossible_a that_o one_o part_n of_o a_o fluid_a can_v be_v under_o pressure_n unless_o the_o next_o adjacent_a part_n be_v under_o the_o same_o degree_n of_o pressure_n therefore_o i_o conclude_v that_o the_o 25_o foot_n and_o a_o half_a of_o air_n ng_z be_v as_o heavy_a as_o the_o 25_o foot_n and_o a_o half_a of_o the_o water_n that_o be_v go_v this_o make_v it_o evident_a also_o that_o when_o the_o pipe_n be_v half_a full_a of_o water_n as_o eke_o the_o air_n ig_n have_v the_o weight_n of_o 952_o pound_n because_o e_z be_v in_o itself_o 1904_o but_o be_v burden_v with_o eke_o 952_o it_o can_v make_v the_o top_n of_o the_o water_n k_o press_v upon_o i_o with_o more_o weight_n than_o 952_o and_o therefore_o by_o the_o 20_o theorem_fw-la the_o air_n give_v must_v weigh_v 952_o likewise_o i_o affirm_v eighthly_a that_o when_o the_o pipe_n be_v full_a of_o water_n from_o e_o to_z g_z if_o a_o man_n poise_v it_o in_o his_o hand_n he_o do_v not_o find_v the_o weight_n of_o the_o water_n eglantine_n and_o the_o reason_n be_v because_o it_o be_v sustain_v by_o the_o part_n of_o the_o surface_n e._n but_o if_o the_o air_n e_o sustain_v it_o my_o hand_n can_v sustain_v it_o i_o find_v then_o only_o the_o weight_n of_o the_o tub_n but_o not_o the_o weight_n of_o the_o water_n within_o it_o i_o say_v ninthly_a that_o when_o i_o poise_v the_o say_a tub_n i_o find_v the_o whole_a weight_n of_o the_o pillar_n of_o air_n lm_o which_o be_v exact_o 1904_o pound_n i_o prove_v it_o thus_o the_o pondus_fw-la of_o a_o fluid_a be_v then_o only_o find_v when_o there_o be_v not_o a_o potentia_fw-la to_o counterpoise_v it_o or_o at_o least_o when_o the_o potentia_fw-la be_v inferior_a to_o the_o pondus_fw-la but_o there_o be_v here_o no_o potentia_fw-la counterpoise_v the_o pondus_fw-la of_o the_o air_n lm_o therefore_o i_o must_v find_v the_o weight_n of_o it_o when_o i_o lift_v up_o the_o tub._n the_o major_a proposition_n be_v clear_a from_o the_o ten_o theorem_fw-la it_o be_v evident_a also_o from_o common_a experience_n for_o while_o a_o balance_n be_v hang_v upon_o a_o nail_n with_o six_o pound_n in_o the_o one_o scale_n and_o nothing_o in_o the_o other_o you_o will_v find_v the_o whole_a burden_n if_o you_o press_v up_o that_o one_o scale_n with_o the_o palm_n of_o your_o hand_n but_o if_o so_o be_v there_o be_v six_o pound_n in_o the_o opposite_a scale_n you_o will_v not_o find_v the_o first_o six_o and_o the_o reason_n be_v because_o it_o be_v in_o equilibrio_n with_o other_o six_o it_o be_v just_a so_o here_o i_o must_v find_v the_o weight_n of_o the_o air_n lm_o while_o i_o poise_v the_o tub_n because_o it_o want_v a_o weight_n to_o counterbalance_v it_o i_o prove_v the_o minor_a proposition_n thus_o if_o any_o thing_n counterbalance_v the_o air_n lm_o it_o must_v either_o be_v the_o air_n below_o namely_o the_o part_n e_o or_o the_o water_n eglantine_n but_o neither_o of_o the_o twain_o can_v do_v it_o not_o the_o air_n e_o because_o it_o have_v as_o great_a a_o burden_n upon_o it_o as_o it_o be_v able_a to_o
support_v namely_o the_o water_n eglantine_n that_o weigh_v 1904_o pound_n and_o for_o this_o cause_n not_o the_o water_n itself_o see_v all_o the_o force_n it_o can_v have_v to_o counterbalance_v lm_o be_v from_o the_o surface_n of_o air_n e_o but_o this_o be_v in_o equilibrio_n with_o it_o already_o i_o say_v that_o the_o air_n lm_o be_v exact_o 1904_o pound_n weight_n this_o also_o be_v evident_a because_o it_o be_v just_a of_o these_o same_o dimension_n with_o the_o air_n fh_v if_o it_o be_v say_v the_o air_n lm_o must_v be_v thick_a see_v its_o equal_a to_o the_o tub_n without_o but_o the_o air_n fh_v be_v only_o equal_a to_o the_o tub_n within_o i_o answer_v it_o be_v so_o indeed_o but_o here_o be_v a_o solution_n to_o the_o difficulty_n i_o do_v not_o find_v the_o whole_a weight_n of_o the_o air_n lm_o but_o only_o as_o much_o of_o it_o as_o be_v equal_a to_o fh_v suppose_v the_o tub_n to_o be_v 12_o inch_n within_o from_o side_n to_o side_n and_o 16_o without_o from_o side_n to_o side_n i_o say_v then_o i_o find_v only_o the_o burden_n of_o so_o much_o air_n as_o answer_n to_o the_o cavity_n of_o the_o tub_n because_o the_o rest_n of_o these_o inch_n be_v counterpoise_v by_o as_o much_o below_o namely_o by_o the_o air_n that_o environ_n the_o orifice_n e_o for_o it_o be_v suppose_v that_o if_o the_o tub_n be_v two_o inch_n thick_o above_o it_o must_v be_v as_o thick_a in_o the_o lip_n so_o that_o the_o whole_a tub_n be_v not_o unequal_o press_v but_o only_o so_o much_o of_o it_o within_o upon_o the_o top_n as_o answer_n to_o the_o cavity_n ten_o that_o when_o the_o pipe_n be_v but_o half_a full_a of_o water_n namely_o from_o e_z to_o k_o i_o find_v only_o 952_o pound_n of_o the_o air_n lm_o though_o before_o i_o find_v 1904._o the_o reason_n be_v because_o the_o one_o half_a of_o it_o be_v now_o counterpoise_v by_o the_o air_n ig_n and_o therefore_o the_o weight_n of_o it_o become_v insensible_a it_o be_v clear_a from_o the_o six_o assertion_n that_o the_o air_n ig_n press_v down_o with_o 952_o therefore_o it_o must_v press_v up_o with_o as_o much_o see_v according_a to_o the_o six_o theorem_n the_o pressure_n of_o a_o fluid_a be_v on_o every_o side_n eleven_o that_o when_o there_o be_v only_o eight_o foot_n of_o water_n and_o a_o half_a in_o the_o tub_n namely_o between_o e_z and_o n_o i_o find_v only_o 476_o pound_n of_o the_o air_n lm_o because_o in_o this_o case_n the_o air_n ng_z counterpoise_v 1428_o pound_n of_o it_o for_o if_o the_o say_a air_n burden_n the_o water_n ne_fw-fr with_o 1428_o pound_n as_o be_v clear_a from_o the_o seven_o assertion_n it_o must_v likewise_o press_v up_o the_o tub_n with_o as_o much_o and_o so_o counterpoise_v as_o much_o of_o the_o air_n lm_o twelve_o that_o when_o there_o be_v nothing_o within_o the_o pipe_n but_o air_n the_o whole_a weight_n of_o the_o air_n lm_o become_v insensible_a to_o i_o the_o reason_n be_v evident_a because_o it_o be_v whole_o counterpoise_v by_o the_o air_n within_o the_o pipe_n i_o affirm_v thirteenthly_a that_o the_o water_n eglantine_n be_v in_o equilibrio_n with_o the_o water_n ab_fw-la that_o be_v to_o say_v 1904_o pound_n be_v in_o equilibrio_n with_o 476_o pound_n i_o prove_v it_o evident_o by_o the_o first_o medium_n all_o the_o part_n of_o a_o horizontal_n surface_n be_v equal_o press_v therefore_o the_o part_n a_o sustain_v no_o more_o burden_n than_o the_o part_n e_o therefore_o ab_fw-la be_v as_o heavy_a as_o eglantine_n and_o consequent_o the_o air_n cd_o must_v be_v as_o heavy_a as_o the_o air_n fh_v lest_o this_o proposition_n may_v seem_v to_o contradict_v what_o be_v already_o say_v i_o must_v distinguish_v a_o twofold_a balance_n according_a to_o the_o three_o theorem_fw-la one_o natural_a another_o artificial_a in_o the_o artificial_a balance_n where_o magnitude_n do_v weigh_v according_a to_o all_o their_o dimension_n viz._n longitude_n latitude_n and_o profundity_n the_o water_n ab_fw-la and_o the_o water_n eglantine_n be_v not_o 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1071_o stone_n weight_n it_o may_v be_v inquire_v next_o what_o be_v the_o weight_n of_o the_o air_n that_o burden_v the_o pavement_n of_o this_o parlour_n that_o be_v 16_o foot_n square_a i_o answer_v 487424_o pound_n because_o it_o be_v exact_o the_o weight_n of_o a_o bulk_n of_o water_n 34_o foot_n high_a and_o 16_o foot_n thick_a it_o be_v to_o be_v remember_v that_o though_o the_o pressure_n of_o it_o be_v so_o much_o yet_o be_v pour_v into_o the_o scale_n of_o a_o balance_n it_o will_v not_o weigh_v so_o much_o for_o not_o only_o as_o much_o as_o fill_v the_o room_n must_v be_v take_v but_o as_o much_o as_o pass_v from_o the_o pavement_n to_o the_o
may_v have_v a_o wide_a vessel_n that_o may_v receive_v the_o same_o glass_n into_o it_o and_o it_o be_v full_a of_o water_n may_v so_o cover_v the_o seal_a orifice_n that_o there_o shall_v be_v no_o hazard_n of_o any_o air_n come_v in_o or_o this_o experiment_n may_v be_v first_o try_v at_o the_o root_n of_o the_o hill_n and_o have_v stop_v complete_o the_o mouth_n of_o the_o vessel_n the_o whole_a engine_n may_v be_v carry_v up_o to_o the_o top_n where_o you_o will_v find_v the_o mercury_n subside_o and_o fall_v down_o so_o much_o namely_o after_o the_o say_a orifice_n be_v open_v for_o as_o the_o stop_n of_o the_o orifice_n at_o the_o root_n of_o the_o hill_n be_v the_o cause_n why_o that_o same_o degree_n of_o pressure_n remain_v in_o the_o stagnant_a liquor_n so_o the_o open_n of_o it_o upon_o the_o top_n of_o the_o hill_n be_v the_o cause_n why_o it_o become_v less_o this_o experiment_n let_v we_o see_v that_o the_o pressure_n of_o the_o air_n seem_v to_o be_v as_o the_o 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there_o be_v no_o smoke_n to_o be_v see_v which_o seem_v to_o evince_v that_o the_o matter_n whereof_o they_o be_v generate_v must_v be_v most_o pure_a and_o subtle_a who_o know_v but_o this_o country_n that_o abound_v with_o coal_n may_v occasion_v more_o thunder_n and_o lightning_n than_o other_o place_n namely_o by_o send_v up_o sulphurous_a exhalation_n to_o the_o middle_a region_n of_o the_o air_n wherewith_o the_o coal-mine_n abound_v observation_n vii_o this_o be_v a_o method_n for_o find_v out_o the_o true_a south_n and_o north_n point_n which_o be_v in_o effect_n very_o difficult_a to_o know_v take_v therefore_o four_o piece_n of_o timber_n each_o one_o of_o they_o five_o foot_n long_o and_o about_o six_o inch_n thick_a square-wise_a sharpen_v their_o end_n and_o fix_v they_o so_o in_o the_o ground_n that_o they_o may_v stand_v perpendicular_a and_o as_o near_o to_o south_n and_o north_n by_o a_o magnetic_a needle_n as_o may_v be_v the_o place_n will_v be_v free_a of_o tree_n or_o of_o any_o such_o impediment_n that_o it_o may_v have_v a_o free_a prospect_n of_o the_o heaven_n as_o for_o their_o distance_n one_o from_o another_o let_v the_o two_o north-most_a and_o the_o south-most_a be_v two_o foot_n asunder_o let_v the_o two_o east-most_a and_o two_o west-most_a be_v but_o one_o foot_n make_v as_o they_o stand_v a_o oblong_a quadrangle_n for_o keep_v they_o equidistant_a above_o as_o well_o as_o below_o take_v four_o bar_n of_o wood_n about_o three_o inch_n broad_a and_o one_o inch_n thick_a and_o nail_v they_o round_o about_o upon_o the_o four_o side_n on_o each_o side_n one_o so_o that_o be_v nail_v on_o horizontal_o they_o may_v make_v right_a angle_n with_o the_o top_n of_o the_o standard_n above_o there_o be_v
follow_v i_o have_v find_v the_o height_n but_o 27_o inch_n and_o five_o ten_o part_n in_o which_o time_n there_o be_v abundance_n of_o rain_n observation_n fourteen_o november_n 7._o 1670._o i_o make_v exact_a trial_n with_o the_o magnetic_a needle_n for_o know_v the_o variation_n and_o i_o find_v it_o vary_v from_o the_o north_n three_o degree_n and_o a_o half_a towards_o the_o west_n hevelius_n write_v from_o dantzick_n to_o the_o royal_a society_n at_o london_n july_n 5._o 1670_o that_o it_o vary_v with_o he_o seven_o degree_n twenty_o minute_n west_n observation_n xv._n december_n 17._o 1669_o i_o observe_v with_o a_o large_a quadrant_n half_o 9_o a_o clock_n at_o night_n the_o foremost_a guard-star_n when_o it_o be_v in_o the_o meridian_n and_o low_a to_o have_v 41_o degree_n 22_o minute_n of_o altitude_n and_o on_o january_n 7._o 1670_o at_o 7_o a_o clock_n in_o the_o morning_n i_o find_v it_o when_o it_o be_v in_o the_o meridian_n and_o high_a to_o have_v 70_o degree_n 27_o 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