Gravesande, Willem Jacob 's
,
An essay on perspective
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on PERSPECTIVE.
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too obliquely, recourſe muſt be had to Problem I. </
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">81.</
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to find the Appearance of a.</
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<
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II.</
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">A is the Foot of the Perpendicular: </
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">Fig. 46.</
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Triangle, E P M, is drawn as directed: </
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">82.</
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T is the accidental Point of the Perpendiculars,
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to the Geometrical Plane.</
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<
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">Thro’ the Point a, the Appearance of A,
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draw a Perpendicular to the Baſe Line; </
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<
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make equal in Repreſentation to the
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M E; </
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">in conſidering this laſt Line, as being
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parallel to the Vertical Line. </
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Extremity I of this Perſpective, to the Point of
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Sight V, draw a Line cutting the Line T a, in
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the Point X; </
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of the Extremity of the propos’d Line.</
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<
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.</
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A, equal to M E, and parallel to the Verti-
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cal Line. </
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">Suppoſe, moreover, that another Line
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is drawn thro’ the Extremity of this Line, and
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that of the propos’d Perpendicular; </
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<
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laſt Line, by the Conſtruction of the Figure
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M E P, will be parallel to the Station Line;
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</
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<
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">and conſequently, its Repreſentation will
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thro’ the Point of Sight; </
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with T a, will be the Extremity of the Repre-
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ſentation ſought. </
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<
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of the firſt Line, made equal to E M; </
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ſequently, V I is that of the ſecond. </
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to be demonſtrated.</
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