Gravesande, Willem Jacob 's
,
An essay on perspective
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on PERSPECTIVE.
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continued, it would cut the Horizontal Line in
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the Point of Sight.</
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<
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">This is done in aſſuming C H equal to {1/3}, or
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{1/4} Part, &</
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<
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<
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to the Foot of the vertical Line; </
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<
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xml:space
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the Perpendicular H E, in the Point H, equal
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to {1/3} or {1/4} Part, &</
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</
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ſought.</
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<
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s
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">Draw a Parallel A B, through the Point A,
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to the Baſe Line, meeting the Line C D in the
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Point B, and let a ſecond Eye be ſuppoſed at
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the ſame Height and Diſtance as the firſt; </
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<
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find F G the Repreſentation of A B for
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ſecond Eye, which continue until it meets the
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Line C E in b, and in this Continuation aſſume
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b a equal to F G; </
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ſought.</
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<
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Eye, is equal to the Height and Diſtance of the
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firſt; </
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Line A B; </
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<
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">and conſequently , the
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of A B muſt be a Part of F G continued, and
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<
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alſo equal to F G: </
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<
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">And therefore becauſe the Perſpective of B is in the Line C E, a b is the
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Perſpective of A B; </
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to the Geometrical Plane, ſee n. </
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ſcarcely uſeful, unleſs for the Decorations of a
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Theatre.</
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