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## 122. Problem II.

82. To find the Appearance of a Point above the

Geometrical Plane.

Let H C be the Baſe Line: And let T be the

accidental Point of the Lines perpendicular

to the Geometrical Plane. This Point will

be in that Place of the Vertical Line, wherein
it is cut by the Prolongation of the Line mea-

ſuring the Height of the Eye; for this laſt

Line is parallel to the ſaid Perpendiculars. And

ſo likewiſe the aforeſaid Point is the ſame as

the Point T of Fig. 44: Let V be the Point of

Sight, S the Station Point, and Q the Station

Point of the upright perſpective Plane, to which

the inclined perſpective Plane is reduced . And
laſtly, let A be the Seat of the given Point.

### 122.1.

## 123. Operation .

Draw two Lines M P and P E ſeparately,

making a right Angle with each other; in one

of which, aſſume P E, equal to the Height of

the given Point, whoſe Perſpective is ſought; and draw the Line E M, making an Angle with

M P, equal to the Angle of Inclination of the

perſpective Plane. Again let fall the Perpen-

dicular A D from the Point A to the Baſe

Line, in which aſſume A L equal to P M, to-

wards the Baſe Line, when the perſpective

Plane is inclined towards the Objects (as we

have here ſuppoſed) but on the other Side of A,

when the perſpective Plane inclines towards the

Eye. Then from the Point A, draw a Line

to the Point S, cutting the Baſe Line in B, and

joyn the Points L and Q, by a Line cutting the

Baſe Line in C. This being done, draw the