Robson, William: Grammigraphia; or the Grammar of Drawing. (London, 1799)

79
Character of the Seven Situations.

parallel foito toe pergpectitie Plane.

1. PARALLEL WITH THE HORIZONTAL AND GROUND LINES.

2. OBLIQUE TO THE HORIZONTAL AND GROUND LINES.

3. PERPENDICULAR TO THE GROUND PLANE.

4. parallel toito tfjc Vertical Plane ann <25rouno plane.

This has Five Variations.—1 On the Ground Plane.

2 Above the Ground Plane.

3 On the Horizontal Plane.

4 Above the Horizontal Plane.

5 On the Perpendicular.

5. ©Clique to toe Vertical plane, out Parallel toito toe

arounB Plane.

This has Four Variations. — 1 On the Ground Plane.

2 Above the Ground Plane.

3 On the Horizontal Plane.

4 Above the Horizontal Plane.

6. ©clique to toe (fcfounU plane, but parallel toito toe

Vertical plane.

This has Tzvo Variations. — 1 On the Perpendicular.

2 Not on the Perpendicular.

7. ©clique to toe ©rouno plane, ann ©clique to toe

Vertical Plane.

These Seven Situations, with their Variations, produce all the Appearances in Nature, curved,
as -well as direct: for these, by their rules, give Position, and the curve is formed upon them.

The Positions, in Part the First, are the Appearances of these Situations respectively on the
Artificial and Real Perspective Planes.