Gravesande, Willem Jacob 's
,
An essay on perspective
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on PERSPECTIVE.
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Line T B X; </
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<
s
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xml:space
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">which interſect in the Point X,
<
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by a Perpendicular to the Baſe Line, in the
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Point G; </
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<
s
xml:id
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xml:space
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">and then the Point X is the Appear-
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ance ſought.</
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<
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.</
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<
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<
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<
s
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xml:space
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">where V, S, T, and H, repreſent
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the ſame Points as thoſe that are denoted with
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the ſame Letters in this Figure; </
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<
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</
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</
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<
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<
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">: T V: </
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<
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</
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<
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<
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">and altern.</
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</
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<
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<
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<
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">: T H + H S: </
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<
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">T V + V O.</
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<
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<
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<
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">This being apply’d to Fig. </
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<
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<
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">and it will be,
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T H: </
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<
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<
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<
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<
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<
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">If now T X be continued, till it cuts the Ho-
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rizontal Line in F; </
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<
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<
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<
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<
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<
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<
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<
s
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">And conſequently,</
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<
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<
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">: T S: </
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<
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<
s
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">Whence it follows, that if a Line be drawn
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ſrom the Eye, to the Point F, it will be paral-
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lel to S B A. </
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<
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">Therefore the Perſpective
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B A, is a Part of B X; </
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<
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tion of A is in the ſaid Line. </
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<
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of a Line perpendicular to the Geometrical
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Plane, in the Point A, paſſes thro’ the Perſpe-
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ctive of the Point A, and thro’ the Point T ;</
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therefore it is a Part of T X. </
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<
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is in the aſoreſaid Perpendicular: </
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<
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ſpective is in T X.</
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<
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<
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<
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ſpective of C L, is a Part of C X; </
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<
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quently, the Appearance of L is in this Line.
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<
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the Point L, thro’ the propos’d Point, it will be
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parallel to the Vertical Line; </
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<
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ſpective is parallel to the Baſe Line. </
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<
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