Marks' first lessons in geometry / In two parts. Objectively presented, and designed for the use of primary classes in grammar schools, academies, etc.

by Bernhard Marks

An oblique line is a straight line that points neither to the horizon nor to the center of the earth.

Note.—After going through with the lessons on angles, the pupils may be told that oblique lines are so called because they form oblique angles with the horizon.

LESSON FOURTH.

REVIEW.

Read all the vertical lines. (Diagram [4].)

Why is q r a vertical line?

What is a vertical line?

Read all the horizontal lines.

Why is 5 6 a horizontal line?