Figure 16-8.--Construction of an ellipse.
PROBLEM IV--Develop an ellipse with a vertical
5. From each point on the inner circle, and parallel
diameter of 6 l/4 inches and a horizontal diameter of 4
to diameter l-l, draw a line toward the outer circle.
7/8 inches. (See fig. 16-8.)
6. From all points on the outer circle, draw lines
parallel to diameter 6-6 so that they intersect with the
lines drawn in step 5.
1. Scribe a circle with a 6 l/4-inch diameter.
7. The points of intersection of the vertical and
2. Use the same center and scribe a circle with a 4
horizontal lines in each quadrant are points on the
3. Develop the inner circle so that each quadrant
8. Sketch in the outline of the ellipse by freehand
or quarter-circle is equally divided into five parts. (See
drawing, or use a french curve. A true and perfect ellipse
problem I and fig. 16-5 .)
must be developed geometrically. The greater the
4. Locate the equal-space division points on the
number of points established, the more nearly perfect
outer circle circumference by radiating lines from the
the ellipse will be.
center point. These lines are to pass through the division
points on the inner circle's circumference. Number
Sometimes the ellipse does not have to be perfect.
these points as indicated in figure 16-8.
In such cases the ellipse is laid out directly on the deck