Gravesande, Willem Jacob 's
,
An essay on perspective
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An ESSAY
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for then, what is on the Right, will appear on
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the Left.</
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<
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">Therefore, I lay my Perſpective Plane upon
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the Geometrical Plane; </
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the Horizontal Plane, and the Figures requir’d
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to be thrown into Perſpective.</
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<
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I.</
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the Geometrical Plane.</
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Line, D V the Horizontal Line, V the Point
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of Sight, D one of the Points of Diſtance, and
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A the given Point.</
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<
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.</
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A B upon the Baſe Line; </
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Concurrence B, draw the Line B V to the Point
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of Sight; </
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">then aſſume B E in the Baſe Line
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equal to B A, and from the Point E draw the
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Line E D to the Point of Diſtance D: </
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Point (a), the Interſection of B V and E D, is
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the Repreſentation ſought.</
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iſſuing from the Eye towards the Point D, and
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another from the Point A towards the Point E;
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are in parallel Planes, aud each make half a
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right Angle with the Perſpective Plane; </
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