An introduction to linear drawing/Chapter 9
the point of view V, draw the two lines E V and U V and the point where these two lines are cut at T by the line X 3 raise a second perpendicular till it strikes P on the line E V. On the tops of the perpendiculars X Y and 3,2 finish the dotted arch passing through the point P and you have the perspective width, height, fcc. of the first arch.
QUESTIONS ON PART II.
- On what does the apparent size of an object depend?
- Is the angle increased or diminished by the distance of the object ?
- When does an object become invisible?
- What is meant by the Vanishing Point?
- What is meant by the Point of Sight?
What is meant by Perspective Drawing? What is meant by the Perspective Plane?
- What are Visual Rays?
- What is the Horizontal Line?
- What is meant by the Centre of the Picture?
- What is the Prime Vertical Line?
- What are the Points of Distance?
- What is the Ground Plane?
- What is the Base Line?
The teacher should now take figure third and ask the name of each line upon it. He should also require each pupil to draw a similar figure, but not of the same dimensions. If the figure be drawn with chalk on a black board before the class, it will be easy to require each pupil to draw a portion of the figure to show that he understands the application of the directions given under the figure.
The same course must be pursued with every other figure. By frequently drawing the figures the pupil will be able to answer the question, "How must you proceed in drawing this or that figure?" As, at first, perfect exactness is not required, the necessary knowledge of terms may be acquired by drawings made without instruments.
It will be seen by the examples of Perspective Drawing here given, that the pupil will not need a real Perspective Plane or plate of glass, if he can imagine one to be between his eye and the object; and, as the teacher may vary the exercises ad infinitum, by requiring figures to be drawn of given dimensions, it is unnecessary to give more examples.