m_o g_o h._n the_o same_o phenomenon_n happen_v in_o take_v the_o air_n out_o of_o the_o narrow_a pipe_n f_o k._n the_o reason_n be_v still_o unequal_a pressure_n for_o in_o remove_v the_o air_n that_o be_v within_o the_o pipe_n the_o part_n of_o the_o surface_n m_o and_o the_o part_n h_n remain_v burden_a while_o the_o part_n g_z be_v free_v of_o its_o burden_n therefore_o this_o part_n of_o the_o surface_n be_v liberate_v of_o its_o burden_n that_o come_v down_o through_o the_o pipe_n instant_o rise_v and_o climb_v up_o as_o far_o as_o the_o outward_a air_n rest_v upon_o m_n and_o h_n can_v raise_v it_o which_o be_v to_o e_o 34_o foot_n for_o the_o pressure_n of_o the_o air_n upon_o the_o surface_v of_o all_o water_n according_a to_o the_o 25_o theorem_fw-la be_v equivalent_a to_o the_o weight_n of_o 34_o foot_n of_o water_n must_v raise_v the_o say_a water_n in_o the_o pipe_n 34_o foot_n you_o do_v not_o wonder_v why_o it_o rise_v from_o i_o to_o g_o as_o in_o the_o first_o experiment_n no_o more_o ought_v you_o to_o wonder_n why_o it_o rise_v from_o g_z to_z e_z see_v the_o weight_n of_o the_o air_n do_v the_o same_o thing_n that_o 34_o foot_n of_o water_n rest_v upon_o the_o surface_n m_o h_n will_v do_v from_o this_o experiment_n we_o see_v first_o that_o the_o pressure_n of_o the_o air_n be_v the_o proper_a cause_n of_o the_o motion_n of_o water_n up_o through_o pump_n and_o siphons_n or_o any_o other_o instrument_n that_o be_v use_v in_o water-work_n of_o that_o kind_n for_o if_o the_o weight_n of_o the_o air_n rest_v upon_o the_o surface_n m_o h_n be_v the_o cause_n why_o the_o water_n climb_v up_o from_o g_z to_z e_z the_o same_o must_v be_v the_o cause_n why_o the_o stagnant_a water_n follow_v the_o sucker_n of_o the_o pump_n while_o it_o be_v pull_v up_o and_o the_o same_o be_v the_o cause_n why_o water_n ascend_v the_o leg_n of_o a_o siphon_n and_o be_v the_o cause_n why_o motion_n continue_v after_o suction_n be_v end_v we_o see_v second_o that_o every_o press_v fluid_a have_v a_o sphere_n of_o activity_n to_o which_o it_o be_v able_a to_o raise_v the_o fluid_a that_o be_v press_v this_o be_v evident_a in_o this_o experiment_n because_o the_o pressure_n of_o the_o air_n rest_v upon_o m_n h_n be_v able_a to_o raise_v the_o water_n the_o height_n of_o e_o in_o the_o wide_a pipe_n and_o the_o height_n of_o f_o in_o the_o narrow_a and_o no_o further_o even_o though_o the_o say_v pipe_n be_v far_o long_o and_o this_o altitude_n and_o high_a point_n be_v precise_o 34_o foot_n between_o air_n and_o water_n we_o see_v three_o that_o it_o be_v all_o one_o matter_n whether_o pump_n and_o siphons_n be_v wide_a or_o narrow_a whether_o the_o tub_n of_o the_o baroscope_n be_v wherein_o the_o mercury_n be_v suspend_v of_o a_o large_a diameter_n or_o of_o a_o lesser_a diameter_n this_o be_v also_o evident_a from_o the_o same_o experiment_n see_v there_o be_v no_o more_o difficulty_n in_o cause_v the_o water_n ascend_v the_o wide_a pipe_n than_o in_o cause_v it_o ascend_v the_o narrow_a one_o and_o the_o reason_n be_v because_o the_o press_a fluid_n repect_v not_o the_o press_v fluid_a according_a to_o its_o thickness_n and_o breadth_n but_o only_o according_a to_o its_o altitude_n therefore_o '_o be_v as_o easy_a for_o the_o air_n to_o press_v up_o water_n through_o a_o pump_n four_o foot_n in_o diameter_n as_o to_o press_v it_o up_o through_o a_o pump_n but_o one_o foot_n in_o diameter_n experiment_n iv._o figure_n 7._o this_o schematism_n represent_v a_o large_a vessel_n full_a of_o water_n who_o first_o and_o visible_a surface_n be_v d_o e_o h_o k._n the_o second_o that_o be_v imaginary_a be_v l_o i_o six_o foot_n below_o it_o the_o three_o of_o the_o same_o kind_n be_v m_n g_o six_o foot_n low_o the_o four_o be_v n_o f_o o_o six_o foot_n yet_o low_o the_o last_o and_o low_a be_v a_o b_o c._n there_o be_v here_o also_o four_o tub_n or_o rather_o one_o tub_n under_o four_o divers_a position_n with_o both_o end_n open_a after_o this_o tub_n d_o a_o be_v thrust_v below_o the_o water_n till_o it_o ascend_v as_o high_a as_o d_o in_o it_o lift_v it_o up_o between_o your_o finger_n till_o it_o have_v the_o position_n of_o the_o second_o pipe_n e_o f_o and_o then_o you_o shall_v see_v as_o the_o orifice_n of_o the_o pipe_n ascend_v the_o cylinder_n of_o water_n fall_v out_o by_o little_a and_o little_a until_o it_o be_v no_o long_o than_o e_o f._n again_o lift_v it_o further_o up_o till_o it_o have_v the_o position_n of_o the_o pipe_n h_o g_o then_o shall_v you_o find_v the_o cylinder_n of_o water_n become_v yet_o short_a last_o if_o it_o be_v situate_v as_o the_o pipe_n k_o i_o the_o internal_a water_n become_v no_o long_a than_o k_o i._o the_o reason_n of_o these_o phenomena_n be_v the_o same_o namely_o unequal_a pressure_n for_o the_o orifice_n a_o be_v lift_v up_o as_o high_a as_o f_o it_o come_v to_o the_o imaginary_a surface_n n_o o_o which_o be_v not_o under_o so_o much_o pressure_n as_o the_o other_o be_v therefore_o one_o part_n of_o it_o be_v more_o burden_v than_o another_o namely_o the_o part_n upon_o which_o the_o cylinder_n of_o water_n rest_v it_o present_o yield_v and_o suffer_v the_o cylinder_n to_o become_v short_a and_o light_a till_o it_o become_v no_o heavy_a than_o be_v proportionable_a to_o its_o own_o strength_n to_o make_v this_o reason_n more_o evident_a it_o be_v to_o be_v note_v that_o no_o surface_n of_o water_n be_v able_a to_o support_v a_o cylinder_n high_a than_o its_o own_o deepness_n that_o be_v to_o say_v if_o a_o surface_n be_v 40_o foot_n deep_a it_o be_v able_a to_o sustain_v a_o cylinder_n 40_o foot_n high_a and_o no_o more_o therefore_o the_o surface_n n_o o_o be_v but_o 18_o foot_n deep_a it_o can_v sustain_v a_o cylinder_n 24_o foot_n long_o for_o if_o that_o be_v than_o the_o potentia_n shall_v be_v inferior_a to_o the_o pondus_fw-la which_o be_v impossible_a in_o the_o hydrostaticks_n in_o effect_n it_o be_v no_o less_o absurdity_n then_o to_o say_v 18_o ounce_n be_v able_a to_o counterbalance_v 24._o for_o a_o second_o trial_n lift_v up_o the_o same_o pipe_n high_o till_o it_o acquire_v the_o position_n of_o the_o tub_n g_o h_n in_o this_o case_n the_o cylinder_n of_o water_n within_o it_o become_v yet_o short_a even_o no_o long_o than_z g_z h._n the_o reason_n be_v the_o same_o namely_o unequal_a pressure_n for_o when_o a_o cylinder_n of_o water_n 18_o foot_n high_a come_v to_o rest_v upon_o this_o surface_n that_o be_v but_o 12_o foot_n deep_a it_o make_v one_o part_n of_o it_o more_o burden_v than_o another_o therefore_o the_o part_n that_o be_v more_o press_v present_o yield_v and_o suffer_v the_o cylinder_n to_o fall_v down_o till_o the_o pondus_fw-la of_o it_o become_v equal_a to_o its_o own_o potentia_fw-la for_o the_o last_o trial_n lift_v up_o the_o tub_n till_o it_o acquire_v the_o position_n of_o the_o pipe_n k_o i_o in_o this_o case_n the_o water_n within_o it_o become_v no_o long_o than_o k_o i_o the_o surface_n l_o i_o that_o be_v but_o six_o foot_n deep_a not_o be_v able_a to_o sustain_v a_o cylinder_n 12_o foot_n high_a from_o this_o experiment_n we_o see_v first_o that_o in_o all_o fluid_a body_n there_o be_v a_o pressure_n which_o be_v more_o or_o less_o according_a to_o the_o deepness_n of_o that_o fluid_a this_o be_v evident_a from_o the_o four_o several_a surface_n there_o be_v more_o pressure_n and_o force_n in_o the_o low_a a_o b_o c_o then_z in_o the_o next_z n_o o_o and_o more_o in_o this_o then_o in_o the_o surface_n m_o g_o and_o more_o in_o this_o then_o in_o l_o 1_n we_o see_v second_o that_o in_o all_o fluid_n there_o be_v a_o pondus_fw-la and_o a_o potentia_n which_o two_o be_v always_o of_o equal_a force_n and_o strength_n the_o potentia_n be_v clear_a and_o evident_a in_o the_o surface_n by_o support_v the_o pillar_n which_o pillar_n be_v nothing_o else_o but_o the_o pondus_fw-la support_v and_o that_o they_o be_v always_o of_o equal_a strength_n be_v most_o evident_a also_o for_o when_o you_o endeavour_v to_o make_v the_o pondus_fw-la unequal_a to_o the_o potentia_n in_o make_v a_o surface_n 18_o foot_n deep_a to_o support_v a_o pillar_n 24_o foot_n high_a they_o of_o their_o own_o accord_n become_v equal_a the_o pillar_n become_v short_a and_o suitable_a to_o the_o strength_n of_o the_o surface_n that_o sustain_v it_o we_o see_v three_o that_o it_o be_v impossible_a for_o one_o part_n of_o the_o same_o horizontal_n surface_n to_o be_v more_o burden_v than_o another_o for_o when_o you_o endeavour_v to_o do_v it_o by_o set_v a_o long_a pillar_n upon_o it_o the_o part_n burden_v
a_o light_a fluid_n be_v able_a to_o press_v with_o as_o great_a burden_n as_o a_o heavy_a figure_n 2._o this_o proposition_n be_v true_a not_o only_o of_o water_n in_o respect_n of_o mercury_n but_o of_o air_n in_o respect_n of_o they_o both_o for_o albeit_o air_n be_v a_o thousand_o time_n light_a than_o water_n yet_o may_v it_o have_v as_o great_a a_o pressure_n with_o it_o as_o water_n as_o be_v evident_a from_o this_o second_o schematism_n where_o by_o the_o pressure_n of_o the_o outward_a air_n g_o h_o a_o b_o twenty_o nine_o inch_n of_o mercury_n o_o p_o be_v support_v as_o well_o as_o the_o twenty_o nine_o inch_n e_o o_fw-fr by_o the_o pressure_n of_o the_o water_n a_o b_o e_o f._n so_o do_v the_o same_o air_n sustain_v the_o thirty_o four_o foot_n of_o water_n n_o r_o which_o be_v real_o as_o heavy_a as_o the_o twenty_o nine_o inch_n of_o mercury_n o_o p._n now_o if_o the_o weight_n of_o the_o atmosphere_n be_v equivalent_a to_o the_o weight_n of_o thirty_o four_o foot_n of_o water_n or_o of_o twenty_o nine_o inch_n of_o mercury_n it_o be_v no_o wonder_n to_o see_v water_n press_v with_o as_o great_a weight_n as_o mercury_n which_o be_v likewise_o cleaâ—_n from_o this_o same_o figure_n where_o by_o the_o pressure_n of_o the_o water_n a_o b_o e_o f_o twenty_o nine_o inch_n of_o mercury_n e_o o_fw-fr be_v suspend_v as_o true_o as_o the_o mercury_n c_o e_o within_z the_o low_a end_n of_o the_o pipe_n be_v support_v by_o the_o outward_a environ_v mercury_n the_o reason_n of_o these_o phenomena_n be_v take_v from_o the_o altitude_n of_o the_o press_a fluid_n for_o though_o a_o body_n be_v never_o so_o light_a yet_o multiplication_n of_o part_n make_v multiplication_n of_o weight_n which_o multiplication_n of_o part_n in_o fluids_n must_v be_v according_a to_o altitude_n for_o multiplication_n of_o part_n according_a to_o thickness_n and_o breadth_n will_v not_o do_v it_o observe_v here_o that_o if_o as_o much_o air_n as_o fill_v the_o tub_n between_o n_o and_o l_o be_v put_v into_o the_o scale_n of_o a_o balance_n it_o will_v exact_o counterpoise_v the_o thirty_o four_o foot_n of_o water_n n_o r_o pour_v into_o the_o other_o scale_n item_n that_o as_o much_o water_n as_o will_v fill_v the_o tub_n between_o e_z and_o a_o be_v just_a the_o weight_n of_o the_o mercury_n e_o o._n last_o that_o as_o much_o air_n as_o will_v fill_v the_o pipe_n between_o o_o and_o g_o be_v just_a the_o weight_n of_o the_o mercury_n o_o p._n theorem_fw-la xxviii_o the_o pressure_n of_o fluids_n do_v not_o diminish_v while_o you_o subtract_v from_o their_o thickness_n but_o only_o when_o you_o subtract_v from_o their_o altitude_n figure_n 1._o for_o understand_v this_o let_v we_o look_v upon_o the_o first_o schematism_n where_o there_o be_v four_o pillar_n of_o water_n now_o i_o say_v though_o you_o cut_v off_o the_o three_o colume_n of_o water_n upon_o the_o right_a side_n yet_o there_o shall_v remain_v as_o much_o pressure_n in_o the_o quadrat_fw-la foot_n of_o water_n q_n as_o be_v while_o these_o be_v entire_a but_o if_o you_o cut_v off_o from_o the_o top_n the_o water_n e_o f_o g_o h_n then_o present_o a_o alteration_n follow_v not_o only_o in_o the_o low_a part_n nigh_o to_o the_o bottom_n but_o through_o all_o the_o intermediat_a part_n for_o not_o only_o the_o water_n q_n lose_v a_o degree_n of_o its_o pressure_n but_o the_o water_n p_o and_o o_o suffer_v the_o same_o loss_n this_o theorem_fw-la hold_v true_a likewise_o in_o order_n to_o the_o element_n of_o air._n for_o if_o by_o divine_a providence_n the_o air_n shall_v become_v less_o in_o altitude_n than_o it_o be_v then_o sure_o the_o bensil_n of_o the_o ambient_fw-la air_n that_o we_o breath_n in_o and_o out_o shall_v be_v by_o proportion_n weaken_v also_o and_o contrariwise_o if_o the_o altitude_n become_v more_o than_o strong_a shall_v the_o bensil_n be_v here_o with_o we_o in_o the_o low_a part_n both_o which_o will_v be_v hurtful_a to_o creature_n that_o live_v by_o breathe_v for_o if_o the_o altitude_n of_o the_o air_n be_v far_o more_o than_o it_o be_v our_o body_n will_v be_v under_o a_o far_o great_a pressure_n which_o sure_o will_v be_v very_o hurtful_a and_o upon_o the_o other_o hand_n if_o the_o altitude_n of_o the_o air_n be_v far_o less_o than_o it_o be_v we_o shall_v be_v at_o a_o great_a loss_n for_o then_o by_o reason_n of_o the_o weak_a bensil_n we_o will_v breathe_v indeed_o but_o with_o great_a difficulty_n theorem_fw-la xxix_o a_o thick_a pillar_n of_o a_o fluid_a be_v not_o able_a to_o press_v up_o a_o slenderer_n unless_o there_o be_v a_o unequal_a pressure_n figure_n 3._o for_o understand_v this_o let_v we_o suppose_v this_o three_o schematism_n to_o represent_v a_o vessel_n with_o water_n in_o it_o as_o high_a as_o a_o b_o among_o which_o be_v thrust_v down_o to_o the_o bottom_n the_o pipe_n g_o h_n open_a at_o both_o end_n i_o say_v then_o the_o two_o thick_a pillar_n of_o air_n e_o a_o and_o f_o b_o press_v upon_o the_o surface_n of_o the_o water_n a_o b_o be_v not_o able_a to_o press_v up_o the_o water_n h_n i_o or_o the_o slender_a pillar_n of_o air_n i_o g_o within_o the_o pipe_n the_o one_o high_a than_o i_o the_o other_o high_a than_o g._n if_o it_o be_v say_v they_o be_v heavy_a because_o they_o be_v thick_a i_o answer_v they_o be_v true_o heavy_a for_o the_o pillar_n of_o air_n f_o b_o apart_z will_v be_v thrice_o as_o heavy_a as_o the_o slender_a pillar_n of_o air_n i_o g._n but_o if_o you_o reckon_v the_o pillar_n of_o air_n e_o a_o upon_o the_o left_a hand_n both_o together_o will_v be_v six_o time_n heavy_a than_o the_o air_n i_o g_o yet_o be_v they_o not_o able_a either_o several_o or_o conjunct_o to_o press_v up_o the_o water_n h_n i_o high_o than_o i_o or_o the_o air_n i_o g_o high_o than_o g._n for_o solve_v this_o difficulty_n i_o must_v say_v conform_a to_o the_o four_o theorem_n that_o fluid_a body_n counterpoise_v one_o another_o not_o according_a to_o their_o thickness_n and_o breadth_n but_o according_a to_o their_o altitude_n only_o therefore_o see_v the_o slender_a pillar_n of_o air_n i_o g_o be_v as_o high_a as_o either_o f_o b_o or_o e_z a_o it_o can_v be_v press_v up_o by_o they_o for_o by_o virtue_n of_o this_o equal_a height_n all_o the_o three_o press_v equal_o and_o uniform_o upon_o the_o surface_n of_o water_n a_o b_o and_o therefore_o according_a to_o the_o twelve_o theorem_n there_o can_v be_v no_o motion_n but_o if_o so_o be_v the_o pillar_n f_o b_o be_v high_o than_o the_o pillar_n i_o g_o then_o sure_o will_v the_o water_n h_n i_o be_v press_v up_o for_o in_o such_o a_o case_n there_o be_v a_o unequal_a pressure_n or_o if_o the_o pillar_n i_o g_o be_v high_a than_o the_o pillar_n f_o b_o then_o sure_o will_v the_o water_n i_o h_n be_v press_v down_o there_o be_v again_o a_o unequal_a pressure_n the_o water_n within_o the_o pipe_n be_v more_o burden_v than_o the_o water_n about_o the_o pipe_n in_o a_o word_n there_o be_v no_o more_o difficulty_n here_o then_o if_o the_o pipe_n be_v take_v away_o in_o which_o case_n there_o will_v be_v but_o one_o pillar_n of_o air_n rest_v upon_o the_o surface_n of_o water_n a_o b._n if_o it_o be_v say_v the_o pipe_n be_v thrust_v down_o make_v of_o one_o pillar_n three_o distinct_a one_o and_o consequent_o a_o formal_a counterbalance_n or_o mutual_a sustentation_n be_v it_o so_o yet_o because_o all_o these_o press_n uniform_o there_o can_v be_v no_o motion_n theorem_fw-la xxx_o fluids_n press_v not_o only_o according_a to_o perpendicular_a line_n but_o according_a to_o crooked_a line_n figure_n 4._o for_o prove_v this_o proposition_n let_v we_o suppose_v a_o b_o c_o d_o to_o be_v a_o large_a vessel_n full_a of_o water_n as_o high_a as_o a_o n_o b_o and_o a_o little_a vessel_n lie_v within_o it_o near_o to_o the_o bottom_n close_o above_o at_o m_o but_o with_o a_o open_a orifice_n downward_o as_o g_z and_o have_v other_o two_o passage_n go_v in_o to_o it_o upon_o the_o right_n and_o leave_v side_n as_o e_z o_o and_o f_o p._n now_o i_o say_v the_o pressure_n of_o this_o water_n be_v not_o only_o from_o n_o to_o m_n in_o a_o straight_a line_n downward_o but_o from_o e_o to_o o_o and_o from_o f_o to_o p_o by_o crooked_a line_n nay_o put_v the_o case_n this_o vessel_n have_v no_o passage_n in_o to_o it_o but_o by_o a_o labyrinth_n or_o entry_n full_a of_o intricate_a wind_n yet_o the_o pressure_n will_v be_v communicate_v through_o all_o these_o even_o to_o the_o middle_n of_o it_o and_o which_o be_v more_o the_o water_n h_n or_o i_o within_o the_o vessel_n will_v be_v under_o the_o same_o
matter_n whither_o the_o glass_n tub_n be_v wide_a or_o narrow_a that_o be_v use_v in_o counterpoise_v fluid_a body_n one_o with_o another_o and_o this_o be_v the_o true_a reason_n why_o it_o be_v no_o matter_n whither_o the_o tub_n of_o the_o baroscope_n be_v a_o wide_a one_o or_o a_o narrow_a one_o see_v the_o air_n do_v not_o counterpoise_v the_o mercury_n according_a to_o thickness_n that_o be_v to_o say_v neither_o the_o thickness_n of_o the_o ambient_fw-la air_n that_o sustain_v nor_o the_o thickness_n of_o the_o mercury_n that_o be_v sustain_v be_v to_o be_v consider_v but_o only_o their_o altitude_n it_o be_v true_a the_o element_n of_o air_n be_v fourteen_o thousand_o time_n high_o than_o the_o mercurial_a cylinder_n yet_o there_o be_v a_o certain_a and_o true_a proportion_n keep_v between_o their_o height_n so_o that_o if_o the_o element_n of_o air_n shall_v by_o divine_a providence_n become_v high_a or_o low_o the_o height_n of_o the_o mercury_n will_v alter_v according_o experiment_n ii_o figure_n 6._o take_v out_o of_o the_o water_n the_o wide_a pipe_n e_o g_o ay_o and_o stop_v the_o orifice_n i_o pour_v in_o water_n above_o at_o e_o till_o the_o tub_n be_v complete_o full_a have_v do_v this_o thrust_v down_o the_o stop_a orifice_n i_o to_o the_o bottom_n of_o the_o vessel_n and_o there_o open_a it_o then_o shall_v you_o see_v the_o water_n fall_v down_o from_o e_z to_z g_z and_o there_o halt_v the_o reason_n be_v take_v from_o unequal_a pressure_n for_o the_o tub_n be_v full_a of_o water_n from_o e_z to_o i_o that_o part_n of_o the_o imaginary_a surface_n upon_o which_o the_o pillar_n of_o water_n rest_v be_v more_o burden_v than_o any_o other_o part_n of_o it_o namely_o more_o than_o l_o or_o k_o therefore_o see_v one_o part_n be_v more_o burden_v than_o another_o the_o cylinder_n of_o water_n that_o cause_v the_o burden_n must_v so_o far_o fall_v down_o till_o all_o the_o part_n be_v alike_o press_v in_o which_o instant_a of_o time_n the_o motion_n cease_v this_o lead_v we_o to_o a_o clear_a discovery_n of_o the_o reason_n why_o in_o the_o baroscope_n the_o mercury_n fall_v from_o the_o top_n of_o the_o tub_n of_o any_o height_n always_o to_o the_o twenty_o and_o nine_o inch_n above_o the_o stagnant_a quicksilver_n for_o example_n fill_v the_o pipe_n n_o q_n which_o be_v sixty_o inch_n high_a with_o mercury_n and_o open_v the_o orifice_n qui_fw-fr the_o liquor_n shall_v fall_v out_o and_o fall_v down_o from_o n_o till_o it_o rest_v at_o r_o which_o be_v twenty_o nine_o inch_n above_o the_o open_a orifice_n q._n the_o reason_n be_v the_o same_o namely_o unequal_a pressure_n see_v one_o part_n of_o the_o imaginary_a surface_n of_o air_n x_o saint_n upon_o which_o the_o cylinder_n of_o mercury_n stand_v be_v more_o burden_a then_o the_o other_o next_o adjacent_a therefore_o so_o long_o and_o so_o far_o must_v the_o mercury_n subside_o and_o fall_v down_o till_o the_o part_n qui_fw-fr upon_o which_o the_o basis_n of_o the_o pillar_n rest_v be_v no_o more_o burden_a than_o the_o rest_n of_o the_o part_n in_o which_o instant_a of_o time_n the_o motion_n cease_v and_o there_o happen_v a_o equal_a balance_n between_o the_o silver_n within_o the_o tub_n and_o the_o air_n without_o if_o it_o be_v say_v i_o see_v a_o clear_a reason_n why_o the_o outward_a water_n m_o l_o aught_o to_o sustain_v the_o inward_a g_o i_o but_o can_v see_v why_o the_o outward_a air_n t_o z_o s_o and_o v_o r_o x_o aught_o to_o sustain_v the_o inward_a mercury_n r_o x_o neither_o do_v i_o see_v a_o reason_n why_o it_o shall_v halt_v at_o r_o as_o the_o water_n rest_v at_o g._n i_o answer_v though_o sense_n can_v perceive_v the_o one_o as_o evident_o as_o the_o other_o yet_o the_o one_o be_v as_o sure_a as_o the_o other_o for_o take_v up_o the_o reason_n why_o it_o halt_v at_o r_o 29_o inch_n above_o x_o you_o must_v remember_v from_o the_o 25_o theorem_fw-la that_o the_o pressure_n of_o the_o air_n upon_o body_n be_v equivalent_a to_o the_o weight_n of_o 34_o foot_n of_o water_n perpendicular_o or_o 29_o inch_n of_o quicksilver_n the_o pillar_n of_o air_n then_o t_o z_o s_o and_o v_z r_z x_o be_v as_o heavy_a each_o one_o of_o they_o as_o two_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 r_o x_o and_o z_o s_o 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 and_o q_o 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 torrieellian_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 leave_v upon_o the_o surface_n m_o h_n 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 e_o g_o 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
instant_o yield_v till_o it_o be_v no_o more_o press_v than_o the_o next_o part_n to_o it_o we_o see_v four_a that_o the_o inequality_n that_o be_v between_o the_o pondus_fw-la and_o the_o potentia_fw-la in_o fluids_n be_v the_o proper_a cause_n of_o the_o motion_n of_o fluids_n for_o when_o you_o endeavour_v to_o make_v a_o surface_n 30_o foot_n deep_a sustain_v a_o pillar_n 40_o foot_n high_a this_o inequality_n be_v the_o true_a cause_n why_o the_o pillar_n subside_v and_o fall_v down_o and_o why_o the_o surface_n yield_v and_o give_v way_n to_o it_o and_o this_o inequality_n be_v the_o true_a cause_n why_o the_o motion_n of_o water_n through_o siphons_n continue_v for_o understand_v this_o you_o must_v conceive_v a_o siphon_n to_o be_v nothing_o else_o but_o a_o crooked_a pipe_n with_o two_o leg_n the_o one_o drown_v among_o water_n the_o other_o hang_v in_o the_o open_a air._n the_o use_n of_o it_o be_v for_o convey_v wine_n or_o water_n from_o one_o vessel_n to_o another_o which_o be_v easy_o do_v by_o suction_n now_o after_o suction_n be_v end_v the_o motion_n of_o the_o water_n continue_v till_o the_o surface_n become_v low_a than_o the_o orifice_n out_o of_o which_o it_o run_v the_o true_a reason_n then_o why_o the_o water_n flow_v out_o be_v the_o inequality_n between_o the_o potentia_fw-la of_o the_o air_n and_o the_o pondus_fw-la of_o the_o water_n the_o pondus_fw-la be_v strong_a than_o the_o potentia_fw-la for_o in_o air_n as_o in_o water_n we_o must_v conceive_v horizontal_n surface_v and_o these_o surface_n to_o be_v endow_v with_o pressure_n and_o force_n as_o be_v the_o surface_v of_o water_n now_o when_o the_o leg_n of_o a_o siphon_n be_v hang_v in_o the_o air_n it_o must_v rest_v upon_o one_o surface_n or_o another_o and_o consequent_o the_o water_n in_o it_o must_v rest_v upon_o the_o same_o surface_n if_o the_o potentia_fw-la of_o the_o surface_n be_v strong_a than_o the_o pondus_fw-la of_o the_o water_n the_o water_n be_v drive_v backward_o which_o always_o come_v to_o pass_v when_o the_o orifice_n be_v high_a than_o the_o surface_n of_o the_o water_n of_o the_o vessel_n among_o which_o the_o other_o leg_n be_v drown_v if_o the_o potentia_fw-la of_o the_o surface_n of_o that_o air_n be_v of_o equal_a power_n and_o strength_n with_o the_o pondus_fw-la of_o the_o water_n the_o water_n go_v neither_o backward_a nor_o forward_o but_o stand_v in_o equilibrio_n this_o happen_v when_o the_o orifice_n be_v neither_o high_o nor_o low_o than_o the_o surface_n of_o the_o water_n in_o the_o vessel_n but_o if_o the_o potentia_fw-la of_o the_o surface_n of_o the_o air_n be_v weak_a than_o the_o pondus_fw-la of_o the_o water_n in_o this_o case_n the_o air_n yield_v and_o suffer_v the_o water_n to_o run_v out_o even_o as_o a_o surface_n 30_o foot_n deep_a yield_v to_o a_o pillar_n of_o water_n 40_o foot_n high_a the_o same_o inequality_n be_v the_o reason_n why_o water_n climb_v up_o the_o pump_n why_o water_n climb_v up_o a_o pipe_n when_o a_o man_n suck_v with_o his_o mouth_n before_o suction_n the_o potentia_n that_o be_v in_o the_o surface_n of_o water_n among_o which_o the_o end_n of_o the_o pipe_n be_v drown_v be_v of_o equal_a force_n with_o the_o pondus_fw-la of_o the_o pillar_n of_o air_n that_o come_v down_o through_o the_o pipe_n or_o pump_n but_o assoon_o as_o a_o man_n begin_v to_o suck_v the_o say_a pillar_n of_o air_n become_v light_a and_o the_o water_n find_v this_o present_o ascend_v the_o same_o be_v the_o reason_n why_o the_o mercury_n fall_v down_o to_o 29_o inch_n in_o the_o baroscope_n and_o no_o further_o for_o as_o long_o as_o the_o pondus_fw-la of_o the_o pillar_n of_o mercury_n exceed_v the_o potentia_fw-la of_o the_o surface_n of_o air_n so_o long_o do_v the_o motion_n continue_v and_o when_o both_o be_v become_v equal_a in_o force_n the_o motion_n cease_v when_o the_o glass-tub_n be_v 40_o inch_n long_o and_o fill_v with_o mercury_n and_o invert_v after_o the_o common_a manner_n you_o be_v endeavour_v as_o it_o be_v to_o cause_v a_o surface_n 29_o inch_n deep_a sustain_v a_o pillar_n 40_o inch_n high_a which_o be_v utter_o impossible_a in_o fluids_n it_o be_v judge_v by_o many_o a_o wonder_n to_o see_v the_o deflux_n of_o the_o mercury_n in_o the_o baroscope_n but_o in_o effect_n there_o be_v no_o more_o cause_n of_o admiration_n in_o it_o than_o to_o see_v the_o cylinder_n of_o water_n grow_v short_a by_o lift_v the_o pipe_n up_o from_o one_o surface_n to_o another_o from_o this_o experiment_n we_o see_v the_o true_a reason_n why_o the_o mercurial_a cylinder_n of_o the_o baroscope_n become_v short_a and_o short_a according_a as_o a_o man_n climb_v up_o a_o mountain_n with_o it_o for_o at_o the_o root_n of_o the_o hill_n the_o surface_n of_o air_n that_o sustain_v the_o pillar_n of_o mercury_n be_v of_o great_a force_n than_o the_o surface_n at_o the_o middle_a part_n and_o this_o be_v strong_a than_o any_o surface_n at_o the_o top_n the_o pipe_n therefore_o be_v carry_v up_o from_o one_o surface_n to_o another_o the_o mercury_n in_o it_o must_v subside_o and_o fall_v down_o even_o as_o the_o water_n fall_v down_o and_o become_v short_a by_o lift_v the_o pipe_n from_o the_o surface_n a_o b_o c_o d_o to_o the_o surface_n n_o o._n and_o as_o the_o whole_a water_n will_v fall_v down_o if_o the_o orifice_n i_o be_v lift_v above_o the_o surface_n d_o e_o h_o k_o so_o if_o the_o baroscope_n can_v be_v carry_v so_o high_a till_o it_o come_v above_o the_o top_n of_o the_o air_n the_o whole_a mercurial_a cylinder_n will_v sure_o fall_v down_o and_o as_o by_o thrust_v down_o the_o say_a pipe_n to_o the_o bottom_n of_o the_o vessel_n again_o as_o the_o pipe_n d_o a_o the_o water_n ascend_v in_o it_o so_o by_o bring_v down_o the_o baroscope_n to_o the_o earth_n again_o the_o whole_a 19_o inch_n will_v rise_v again_o experiment_n v._o figure_n 8._o fill_v the_o vessel_n a_o d_o g_o h_o with_o water_n to_o the_o brim_n next_o thrust_v down_o the_o open_a orifice_n of_o the_o tub_n d_o a_o to_o the_o bottom_n and_o you_o shall_v see_v the_o water_n ascend_v in_o it_o as_o high_z as_o d_o according_a to_o the_o first_o experiment_n when_o this_o be_v do_v recline_v the_o say_a pipe_n till_o it_o lie_v as_o b_o e_z and_o you_o shall_v find_v the_o pipe_n complete_o full_a of_o water_n next_o erect_v the_o same_o tub_n again_o as_o d_o a_o and_o you_o shall_v see_v the_o cylinder_n of_o water_n fall_v down_o and_o become_v short_a as_o at_o first_o for_o salve_v this_o phenomenon_n and_o such_o like_a i_o must_v suppose_v this_o water_n to_o be_v 50_o inch_n deep_a and_o the_o tub_n i_o a_o and_o b_o e_z 90_o inch_n long_o and_o the_o say_a tub_n in_o recline_v to_o describe_v the_o quadrant_a of_o a_o circle_n f_o e_o g._n now_o the_o question_n be_v why_o there_o be_v but_o 50_o inch_n of_o water_n in_o the_o tub_n while_o erect_v there_o shall_v be_v 60_o in_o it_o when_o it_o be_v recline_v second_o why_o there_o shall_v be_v 90_o inch_n of_o water_n in_o the_o tub_n b_o e_o and_o but_o 50_o in_o it_o when_o it_o stand_v perpendicular_a as_o d_o a_o if_o you_o reply_v because_o there_o be_v 90_o inch_n in_o recta_fw-la linea_fw-la between_o the_o point_n b_o and_o the_o point_n e_o and_o but_o 50_o between_o a_o and_o d._n but_o this_o will_v not_o answer_v the_o case_n because_o if_o you_o stop_v the_o orifice_n e_o with_o the_o pulp_n of_o your_o finger_n before_o it_o be_v erect_v you_o will_v find_v the_o tub_n remain_v full_a of_o water_n even_o while_o it_o stand_v perpendicular_a and_o fall_v down_o when_o the_o orifice_n be_v open_v or_o while_o the_o tub_n stand_v perpendicular_a stop_v the_o orifice_n i_o and_o recline_v it_o as_o b_o e_z yet_o no_o more_o water_n will_v be_v find_v in_o it_o than_o 50_o inch_n but_o by_o unstop_v the_o say_a orifice_n the_o water_n climb_v up_o from_o r_z to_z e_z and_o become_v 90_o inch_n now_o what_o be_v the_o reason_n why_o it_o run_v up_o from_o r_z to_z e_z and_o why_o it_o fall_v down_o from_o i_o to_o d_o i_o answer_v then_o the_o water_n must_v run-up_v from_o r_z to_z e_z because_o of_o the_o inequality_n that_o be_v between_o the_o pondus_fw-la of_o the_o cylinder_n b_o r_o and_o the_o potentia_fw-la of_o the_o surface_n of_o water_n a_o b_o c_o that_o support_v the_o say_v cylinder_n for_o understand_v this_o know_v while_o the_o tub_n be_v erect_v there_o be_v a_o perfect_a equality_n between_o the_o weight_n of_o the_o pillar_n a_o d_o and_o the_o force_n or_o power_n of_o the_o surface_n that_o sustain_v it_o see_v a_o surface_n 50_o inch_n deep_a support_v a_o pillar_n 50_o inch_n
with_o air_n as_o be_v clear_a from_o daily_a experience_n the_o liquor_n will_v run_v out_o constant_o at_o b._n because_o there_o be_v here_o a_o unequal_a pressure_n the_o surface_n of_o air_n n_o b_o be_v more_o burden_v than_o the_o surface_n e_o l_o c_o but_o where_o unequal_a pressure_n be_v in_o fluid_n according_a to_o the_o 12_o theorem_n motion_n must_v follow_v i_o prove_v the_o surface_n n_o b_o to_o be_v more_o burden_v than_o the_o surface_n e_o l_o c_o because_o the_o water_n b_o d_o be_v heavy_a than_o the_o water_n l_o d_o as_o be_v evident_a to_o the_o eye_n the_o air_n b_o therefore_o sustain_v far_o more_o weight_n than_o the_o air_n e_o l_o mun_o cede_fw-la and_o yield_v next_o there_o be_v here_o a_o pondus_fw-la and_o a_o potentia_fw-la the_o pondus_fw-la be_v the_o water_n l_o d_o the_o potentia_fw-la by_o which_o it_o be_v counterpoise_v be_v the_o water_n b_o d_o but_o these_o be_v unequal_a b_o d_o being_z heavy_a than_o l_o d_o therefore_o according_a to_o the_o 33_o theorem_fw-la these_o two_o fluid_n can_v cease_v from_o motion_n if_o it_o be_v say_v that_o the_o surface_n n_o b_o be_v strong_a than_o the_o surface_n e_o l_o c_o see_v it_o be_v low_a i_o answer_v the_o difference_n be_v so_o unsensible_a that_o they_o may_v be_v judge_v but_o one_o now_o i_o say_v if_o this_o siphon_n work_n in_o air_n with_o water_n it_o must_v likewise_o work_n in_o water_n with_o mercury_n therefore_o this_o siphon_n be_v 34_o foot_n below_o the_o first_o surface_n f_o g_o the_o liquor_n must_v run_v out_o constant_o at_o b._n because_o there_o be_v here_o a_o unequal_a pressure_n the_o surface_n of_o water_n n_o b_o be_v more_o burden_v than_o the_o surface_n e_o l_o c._n though_o there_o be_v more_o weight_n in_o n_o b_o than_z in_o e_z l_o c_o because_o it_o be_v low_a yet_o because_o the_o difference_n be_v not_o so_o much_o as_o be_v between_o the_o weight_n of_o b_o d_o and_o the_o weight_n of_o l_o d_o it_o prove_v nothing_o note_v here_o that_o so_o long_o as_o d_o be_v within_o 58_o inch_n of_o e_o l_o c_o this_o siphon_n will_v work_v the_o reason_n be_v because_o the_o pressure_n of_o 34_o foot_n of_o water_n with_o the_o pressure_n of_o the_o air_n upon_o f_o g_o be_v able_a to_o raise_v mercury_n exact_o 58_o inch_n but_o if_o d_o exceed_v that_o height_n no_o art_n will_v make_v the_o liquor_n run_v out_o at_o b._n note_v second_o that_o this_o siphon_n will_v operate_v with_o air_n and_o water_n though_o the_o top_n d_o be_v 34_o foot_n above_o m_n and_o the_o reason_n be_v because_o the_o pressure_n of_o the_o air_n be_v able_a to_o raise_v a_o pillar_n of_o water_n to_o that_o height_n note_n three_o that_o if_o there_o be_v a_o orifice_n open_v at_o c_o upon_o the_o level_a line_n e_o l_o c_o the_o two_o water_n will_v become_v of_o the_o same_o weight_n the_o one_o not_o be_v able_a to_o move_v the_o other_o if_o you_o bear_v a_o hole_n at_o r_o the_o liquor_n ascend_v from_o r_z to_z d_o and_o go_v down_o from_o d_o to_o a_o and_o so_o the_o motion_n end_v but_o if_o the_o leg_n a_o d_o be_v six_o time_n wide_a than_o b_o d_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 b_o d_o be_v heavy_a than_o l_o d_o 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 a_o e_o l_o 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 l_o d_o be_v twice_o as_o wide_o as_o the_o shank_n b_o d_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 l_o d_o than_o d_o b._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 a_o b_o 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 a_o c._n and_o e_z g_z 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 e_o f._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 c_o d_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 a_o b_o be_v 168_o pound_n therefore_o the_o air_n c_o d_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 c_o d_o must_v be_v as_o heavy_a as_o the_o pillar_n of_o water_n a_o b._n i_o say_v second_o that_o the_o pillar_n of_o air_n f_o h_n weigh_v 672_o pound_n i_o prove_v it_o thus_o the_o water_n e_o g_z weigh_v 672_o pound_n therefore_o the_o air_n f_o h_n weigh_v as_o much_o the_o antecedent_n be_v clear_a because_o e_z g_o 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 a_o b_o to_o be_v 34_o foot_n high_a and_o the_o pipe_n e_o g_o to_o be_v as_o much_o i_o assert_v then_o three_o the_o pillar_n of_o air_n c_o d_o to_o weigh_v 476_o pound_n which_o i_o prove_v
where_o four_o mill_n go_v with_o the_o water_n that_o come_v from_o under_o ground_n out_o of_o the_o coal_n which_o kind_n of_o level_n be_v only_o find_v where_o the_o coal_n lie_v in_o a_o field_n which_o have_v a_o considerable_a rise_n or_o ascent_n above_o ground_n there_o be_v a_o necessity_n to_o make_v use_n of_o the_o other_o two_o way_n speak_v of_o for_o dry_v the_o coal_n when_o the_o field_n in_o which_o it_o lie_v be_v a_o plain_n further_o of_o these_o coal_n which_o be_v dry_v by_o the_o free-level_n for_o so_o they_o term_v the_o level_n that_o run_v unforced_a there_o be_v some_o to_o which_o this_o kind_n of_o damp_n be_v more_o incident_a than_o to_o other_o the_o cause_n of_o which_o difference_n be_v find_v to_o be_v the_o solidity_n and_o clossness_n of_o the_o metal_n whether_o of_o coal_n or_o stone_n wherein_o some_o exceed_v another_o there_o be_v some_o that_o be_v full_a of_o rift_n or_o empty_a space_n i_o mean_v empty_a of_o any_o part_n of_o the_o same_o body_n where_o they_o be_v which_o will_v sometime_o serve_v to_o convey_v a_o considerable_a quantity_n of_o water_n in_o place_n of_o a_o aquaduct_a or_o level_a which_o space_n be_v term_v by_o the_o vulgar_a cutter_n which_o sometimes_o prove_v very_o profitable_a in_o the_o ground_n where_o they_o be_v find_v both_o in_o regard_n of_o the_o use_n they_o serve_v for_o in_o stead_n of_o level_n and_o for_o render_v the_o metal_n wherein_o they_o be_v find_v more_o easy_a to_o work_v in_o make_v they_o yield_v easy_o to_o the_o force_n of_o the_o wedge_n and_o leaver_n other_o metal_n there_o be_v wherein_o few_o of_o these_o cutter_n be_v to_o be_v find_v and_o if_o water_n be_v to_o be_v convey_v through_o they_o there_o be_v a_o necessity_n of_o cut_v a_o passage_n through_o they_o for_o that_o effect_n now_o this_o damp_n whereof_o we_o speak_v be_v find_v most_o frequent_o and_o most_o violent_a in_o the_o first_o sort_n of_o metal_n viz._n in_o these_o which_o be_v full_a of_o cutter_n or_o rift_n which_o give_v some_o ground_n to_o this_o conjecture_n of_o its_o cause_n these_o space_n which_o be_v find_v in_o coal_n or_o other_o metal_n as_o stone_n or_o till_n before_o the_o coal_n begin_v to_o be_v dry_v by_o a_o level_n be_v full_a of_o water_n which_o be_v still_o in_o motion_n as_o be_v all_o subterraneous_a spring_n whereof_o some_o be_v more_o violent_a some_o more_o slow_a conform_v to_o the_o passage_n they_o have_v to_o the_o fountain_n above_o ground_n where_o they_o discharge_v themselves_o now_o for_o dry_v these_o coal_n and_o render_v they_o workable_a there_o be_v a_o necessity_n to_o cut_v a_o passage_n through_o which_o that_o water_n discharge_v itself_o quick_o it_o be_v large_a and_o admit_v a_o great_a quantity_n at_o once_o by_o virtue_n whereof_o a_o great_a field_n be_v drain_v at_o once_o and_o the_o source_n not_o be_v able_a to_o furnish_v so_o much_o water_n as_o the_o conduit_n be_v able_a to_o convey_v these_o space_n in_o the_o body_n of_o the_o metal_n be_v empty_v of_o water_n must_v needs_o be_v fill_v with_o air_n which_o air_n have_v little_a contact_n and_o commerce_n with_o the_o great_a body_n of_o air_n above_o ground_n and_o so_o have_v little_a or_o â—o_o motion_n corrupt_v in_o these_o place_n and_o thereby_o become_v poisonable_a so_o that_o when_o any_o animal_n be_v necessitat_fw-la to_o draw_v it_o and_o respire_v by_o it_o it_o choke_v they_o on_o a_o sudden_a just_a as_o stand_a water_n which_o be_v without_o motion_n corrupt_v and_o become_v poisonable_a though_o haply_o not_o in_o so_o great_a a_o degree_n as_o the_o air_n the_o air_n be_v a_o body_n much_o â—iner_a and_o pure_a than_o water_n that_o hold_v good_a in_o it_o corruptio_fw-la optimi_fw-la pessima_fw-la this_o be_v much_o confirm_v by_o what_o be_v before_o assert_v that_o in_o the_o coal_n whence_o the_o water_n be_v draw_v and_o they_o drain_v but_o not_o by_o free-course_n but_o by_o force_n as_o pump_v and_o draw_v by_o bucket_n these_o damp_n be_v seldom_o or_o never_o find_v because_o the_o passage_n of_o the_o water_n be_v force_v it_o do_v not_o so_o sudden_o dry_v the_o metal_n as_o the_o other_o whereby_o there_o be_v always_o leave_v in_o these_o space_n some_o water_n which_o be_v itself_o in_o motion_n keep_v the_o air_n also_o in_o motion_n with_o it_o and_o thereby_o the_o air_n be_v keep_v from_o corruption_n at_o least_o in_o such_o a_o degree_n as_o it_o be_v in_o the_o other_o hence_o we_o find_v that_o in_o these_o kind_n of_o coal_n the_o room_n underground_o be_v always_o wet_a or_o for_o the_o most_o part_n they_o be_v so_o whereas_o in_o the_o other_o there_o will_v be_v no_o water_n find_v to_o wash_v a_o man_n hand_n and_o sometime_o the_o coal_n through_o want_n of_o water_n become_v so_o dry_a that_o it_o can_v be_v wrought_v in_o great_a piece_n as_o other_o but_o crush_v in_o the_o very_a work_n and_o when_o wrought_v be_v render_v useless_a and_o will_v not_o at_o all_o bourn_n this_o put_v i_o in_o mind_n of_o a_o very_a pleasant_a conception_n of_o a_o worthy_a and_o learned_a person_n doctor_n george_n hepburn_n of_o monk-ridge_n with_o who_o i_o have_v occasion_n one_o day_n to_o discourse_n on_o this_o subject_a he_o be_v of_o opinion_n that_o the_o water_n be_v the_o mother_n of_o the_o coal_n whereby_o it_o be_v preserve_v fresh_a and_o incorrupt_v and_o that_o when_o the_o water_n be_v draw_v off_o and_o this_o damp_n follow_v it_o be_v not_o the_o air_n which_o succeed_v in_o place_n of_o the_o water_n and_o be_v corrupt_v for_o want_n of_o motion_n that_o occasion_n it_o but_o as_o we_o see_v when_o the_o corruption_n of_o a_o liquor_n within_o a_o vessel_n when_o the_o mother_n be_v go_v corrupt_v the_o vessel_n itself_o and_o occasion_n a_o ill_a savour_n or_o taste_v in_o the_o vessel_n so_o that_o the_o coal_n be_v corrupt_v by_o the_o want_n of_o its_o mother_n the_o water_n corrupt_v the_o air_n in_o the_o 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when_o man_n draw_v with_o ordinary_a bucket_n or_o when_o there_o be_v a_o horse-work_n or_o waterwork_n and_o that_o either_o by_o a_o chain_n with_o plate_n and_o a_o pump_n or_o with_o a_o chain_n and_o bucket_n all_o which_o be_v very_o common_a especial_o those_o we_o have_v in_o scotland_n they_o be_v capable_a to_o draw_v but_o a_o very_a small_a draught_n make_v only_a use_n of_o one_o sink_v for_o that_o effect_n but_o there_o be_v to_o be_v see_v in_o the_o north_n of_o england_n in_o bishopric_n water-work_n by_o which_o water_n be_v draw_v above_o 40_o fathom_n in_o perpendicular_a but_o not_o all_o in_o one_o sink_n the_o manner_n whereof_o be_v thus_o there_o be_v a_o sink_v from_o the_o end_n of_o their_o level_n to_o the_o surface_n of_o the_o earth_n where_o their_o work_n be_v go_v 40_o fathom_n deep_a which_o must_v dry_v the_o coal-sinks_n at_o 60_o or_o 70_o which_o lie_v above_o the_o bank_n of_o the_o river_n where_o the_o water-work_n be_v situate_v there_o 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who_o for_o procure_v a_o fall_n of_o water_n which_o may_v serve_v the_o wheel_n of_o all_o the_o three_o sink_n have_v erect_v the_o first_o work_n upon_o pillar_n like_o a_o windmill_n pretty_a high_a above_o ground_n from_o which_o the_o water_n fall_v make_v the_o second_o go_v close_o above_o ground_n and_o to_o make_v the_o water_n fall_v to_o the_o three_o the_o whole_a wheel_n be_v make_v go_v within_o the_o surface_n of_o the_o ground_n which_o terminat_n at_o a_o river_n under_o the_o work_n which_o mine_n be_v of_o a_o considerable_a length_n where_o water_n can_v be_v have_v to_o make_v such_o work_v go_v they_o use_v horse-work_n but_o not_o wâ—th_o so_o good_a success_n be_v more_o chargeable_a and_o not_o have_v so_o much_o force_n and_o power_n as_o the_o water-work_n but_o i_o be_o of_o opinion_n that_o wind-work_n may_v serve_v well_o where_o water_n can_v be_v have_v and_o when_o no_o wind_n shall_v happen_v to_o blow_v the_o same_o work_n may_v be_v supply_v by_o 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the_o true_a height_n of_o the_o ground_n where_o the_o coal_n lie_v must_v be_v first_o take_v that_o it_o may_v be_v know_v how_o much_o of_o the_o field_n can_v be_v drain_v by_o it_o which_o must_v be_v do_v either_o with_o a_o quadrant_n or_o with_o a_o instrument_n make_v express_v then_o care_n must_v be_v take_v to_o take_v the_o low_a part_n for_o the_o mouth_n of_o the_o level_n that_o the_o field_n can_v afford_v and_o from_o that_o it_o must_v be_v carry_v in_o a_o straight_a line_n towards_o that_o part_n of_o the_o field_n where_o the_o coal_n be_v think_v to_o be_v encounter_v by_o the_o mine_n in_o work_v
whereof_o two_o thing_n be_v in_o a_o special_a manner_n to_o be_v regard_v first_o that_o the_o level_v be_v wrought_v without_o ascent_n or_o descent_n the_o best_a way_n for_o try_v this_o be_v by_o the_o surface_n of_o the_o water_n pass_v through_o it_o which_o ought_v to_o be_v as_o little_a move_n as_o can_v be_v for_o the_o loss_n of_o one_o foot_n of_o level_n which_o the_o ground_n give_v be_v a_o loss_n of_o a_o considerable_a parcel_n of_o coal_n to_o be_v dig_v especial_o if_o it_o be_v flate_z it_o there_o occur_v any_o metal_n which_o be_v impregnable_a in_o the_o course_n of_o the_o level_n so_o that_o it_o be_v impossible_a to_o follow_v so_o straight_o a_o line_n in_o regard_n the_o mine_n must_v be_v wrought_v over_o the_o top_n of_o that_o stone_n which_o be_v unworkable_a in_o that_o case_n there_o be_v but_o one_o of_o two_o to_o serve_v the_o loss_n of_o level_n either_o the_o coal_n rise_v iâ—_n streek_n towards_o which_o the_o mine_n be_v carry_v and_o if_o 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itself_o the_o water_n that_o come_v from_o it_o will_v not_o pass_v over_o any_o height_n in_o its_o way_n but_o will_v be_v unquestionable_o stop_v therefore_o in_o case_n such_o a_o impediment_n can_v not_o be_v remove_v as_o many_o time_n such_o metal_n will_v fall_v in_o which_o be_v unworkable_a in_o a_o direct_a line_n the_o use_n of_o a_o siphâ—n_n may_v be_v try_v which_o will_v unquestionable_o supply_v the_o loss_n of_o about_o 32_o foot_n of_o level_n this_o be_v the_o height_n in_o perpendicular_a to_o which_o the_o pressure_n of_o the_o air_n be_v able_a to_o raise_v water_n up_o through_o a_o siphon_n the_o next_o thing_n to_o be_v observe_v in_o carry_v on_o of_o level_n be_v the_o air-hole_n for_o which_o there_o be_v a_o necessity_n indispensable_a in_o set_v down_o whereof_o care_n must_v be_v have_v that_o they_o be_v not_o direct_o upon_o the_o mine_n lest_o rubbish_n fall_v through_o from_o above_o ground_n shall_v stop_v and_o obstruct_v the_o same_o and_o so_o obstruct_v the_o course_n of_o the_o water_n and_o therefore_o it_o be_v better_a they_o be_v set_v down_o at_o a_o side_n their_o only_a use_n be_v to_o communicate_v fresh_a air_n to_o the_o workman_n which_o if_o it_o can_v be_v otherwise_o supply_v as_o i_o think_v it_o not_o utter_o impossible_a will_v render_v the_o charge_n of_o the_o coal-work_n a_o great_a deal_n more_o easy_a other_o thing_n may_v be_v speak_v to_o of_o level_n as_o that_o some_o run_v with_o the_o course_n of_o metal_n they_o pass_v through_o and_o that_o some_o run_v against_o that_o course_n and_o of_o bring_v level_n from_o the_o dip_v of_o a_o upper-coal_n which_o have_v a_o level_n of_o its_o own_o to_o dry_v a_o coal_n lie_v under_o it_o which_o can_v be_v otherwise_o do_v but_o these_o thing_n be_v common_a and_o obvious_a to_o any_o who_o have_v but_o the_o small_a skill_n and_o experience_n i_o shall_v forbear_v this_o confuse_a account_n your_o importunity_n have_v draw_v from_o i_o for_o which_o if_o your_o book_n suffer_v censure_n which_o i_o grant_v it_o may_v do_v as_o to_o this_o part_n of_o it_o you_o be_v to_o blame_v yourself_o and_o so_o i_o rest_v and_o be_o etc._n etc._n finis_fw-la postscript_n reader_n that_o thou_o may_v know_v the_o rise_n and_o occasion_n of_o this_o postscript_n which_o i_o have_v subjoin_v i_o shall_v give_v thou_o this_o short_a account_n when_o this_o book_n be_v first_o commit_v to_o the_o press_n i_o send_v a_o intimation_n thereof_o to_o several_a person_n who_o i_o judge_v will_v encourage_v it_o yet_o to_o none_o but_o to_o such_o in_o who_o kindness_n i_o have_v confidence_n and_o who_o i_o judge_v my_o real_a friend_n among_o other_o i_o send_v over_o to_o saint_n andrews_n one_o of_o my_o edict_n to_o one_o or_o two_o there_o in_o who_o i_o trust_v but_o in_o stead_n of_o a_o kindly_a return_n from_o they_o to_o who_o i_o have_v write_v most_o affectionate_o they_o write_v back_o a_o letter_n wherein_o they_o supercilious_o 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