angle_n level_n etc._n etc._n and_o a_o particular_a arithmetical_a instrument_n for_o perform_v all_o operation_n in_o arithmetic_n with_o the_o great_a ease_n swiftness_n and_o certainty_n imaginable_a p._n 44,45_o that_o the_o reader_n may_v be_v the_o more_o certain_a of_o this_o the_o author_n describe_v a_o instrument_n for_o take_v angle_n in_o the_o heaven_n who_o perfection_n more_o than_o common_a consist_v 1._o in_o the_o manife_n sting_n of_o the_o sight_n 2._o in_o the_o division_n 3._o in_o the_o reflective_a construction_n of_o the_o sight_n 4._o in_o its_o exact_a perpendicularity_n 5._o in_o its_o fixation_n and_o motion_n fit_a for_o observation_n 6._o in_o its_o facility_n for_o make_v and_o 7._o in_o its_o cheapness_n p._n 45_o 46._o a_o explication_n of_o the_o make_v and_o singular_a convenience_n of_o these_o new_a sight_n p._n 46_o 47_o 48._o a_o explication_n of_o the_o new_a way_n of_o divide_v and_o the_o great_a advantage_n of_o it_o above_o other_o p._n 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new_a way_n of_o order_v sight_n take_v notice_n of_o ibid._n and_o the_o whole_a contrivance_n more_o particular_o describe_v p._n 56._o and_o explain_v by_o a_o delineation_n and_o the_o manner_n how_o they_o be_v applicable_a to_o a_o quadrant_n or_o other_o instrument_n p._n 57_o how_o they_o be_v make_v use_n of_o for_o take_v a_o angle_n big_a than_o a_o quadrant_n be_v far_a describe_v and_o make_v more_o intelligible_a by_o a_o delineation_n p._n 58._o the_o way_n of_o adjust_v the_o two_o fix_a sight_n so_o as_o to_o look_v forward_o and_o backward_o exact_o in_o a_o right_a line_n and_o how_o to_o adjust_a and_o fix_v the_o sight-thread_n in_o the_o tubes_fw-la with_o the_o reason_n thereof_o p._n 59_o 60._o a_o description_n of_o the_o water-level_a for_o set_v the_o instrument_n exact_o horizontal_n some_o difficulty_n and_o the_o way_n of_o prevent_v they_o propose_v p._n 61_o 62._o this_o instrument_n far_o explain_v by_o a_o delineation_n and_o the_o reason_n of_o its_o 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