Gravesande, Willem Jacob 's
,
An essay on perspective
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on PERSPECTIVE.
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rence with the Geometrical Line; </
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<
s
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">which would
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come to the ſame thing.</
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<
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<
s
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">Firſt continue the Line E a, until it meets
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the Horizontal Line in D, and draw a Line
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from D to the Eye, and another through the Eye
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parallel to the Baſe Line.</
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<
s
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">Then the Parallels O M and F C are at the
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ſame Diſtance from each other, as L D is from
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E B; </
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">whence it follows, that F O is equal to E D,
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and therefore O D is parallel to A F. </
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<
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">Whence
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the Appearance of E A, is a Part of E D. </
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after the ſame Manner we prove, that the Re-
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preſentation of B A is a Part of B a.</
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<
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">When there are no Lines drawn, and we
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would uſe this Method, the Horizontal Line
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may be laid aſide; </
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">and then having firſt drawn
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the Geometrical Line, whoſe Diſtance from
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the Baſe Line is equal to the Length of the Ray,
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we aſſume the Diſtance from the Eye to the
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Geometrical Line, equal to the Height of the
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Eye.</
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<
s
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">Although this Method appears uſeleſs, as being
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more difficult than the precedent ones, yet in
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the Eighth Chapter we have ſhewn the Uſe that
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may be drawn from it.</
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<
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<
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">It follows from this Demonſtration, that
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the Appearances of Lines paſſing through the
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Station Point, are all perpendicular to the Baſe
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Line; </
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