## Full text: Gravesande, Willem Jacob: An essay on perspective

An ESSAY tal Plane, or one of the Points of Diſtance on the
Horizontal Line.

The Repreſentation of two Points of theſe
Figures muſt be firſt found ; and then by Means of theſe two Points the Appearances of others

24.
38.

## 112. Example .

Let A B C D E, be a Pentagon, whoſe Ap-
pearance is requir’d; V the Point of Sight; and
V F the ſixth Part of the Eye’s Diſtance from
the perſpective Plane. Now find b and e the Appearance of B and E, by means of which,
the Appearance of the Point A will be had . In like Manner, by means of the Repreſenta-
tion of A and E, will that of D be had; and
by uſing B and A, the Perſpective of C may be
found.

### 112.1.

Fig. 40.
24.
38.

76. Note, the Perſpective of Lines perpendicu-
lar to the Geometrical Plane ; as alſo of Lines inclined thereto , may be found by the Methods of the precedent Chapter.

55.
69.

## 113. Problem II.

77. To throw Figures, which are in the Geometri-
cal Plane into Perſpective, when the Eye is ſo oblique
that it cannot be marked in the Horizontal Plane,
or the Point of Sight in the Horizontal Line.

We muſt proceed here according to the Di-
rections of the precedent Problem, after having
found the Perſpective of ſeveral Points of the
given Figures.

At any Point C, taken at Pleaſure in the Baſe
Line, draw the Perpendicular C D to the ſaid
Line, and likewiſe draw the Line C E from the
ſame Point in ſuch manner, that if it could be

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