al line A, and E 60
degrees from A. Either would be correct.

[Illustration: _Fig. 112. Section Lining_]

SECTION LINING.--In representing many parts of a machine, or article, it
is necessary to show the parts cut off, which must be illustrated by
what is called "section lining." Adjacent parts should have the section
lines running at right angles to each other, and always at 45 degrees.

Look at the outside and then the inside views of Fig. 112, and you will
see how the contiguous parts have the angles at right angles, and
clearly illustrate how every part of the wrench is made. Skill in
depicting an article, for the purpose of constructing it from the
drawing, will make the actual work on the bench and lathe an easy one.

[Illustration: _Fig. 113. Drawing an Ellipse_]

MAKING ELLIPSES AND IRREGULAR CURVES.--This is the hardest thing to do
with drawing tools. A properly constructed elliptical figure is
difficult, principally, because two different sized curves are
required, and the pen runs from one curve into the other. If the two
curves meet at the wrong place, you may be sure you will have a
distorted ellipse.

Follow the directions given in connection with Fig. 113, and it will
give you a good idea of merging the two lines.

First. Draw a horizontal line, A, which is in the direction of the major
axis of the ellipse--that is, the longest distance across. The narrow
part of the ellipse is called the minor axis.

Second. Draw a perpendicular line, B, which we will call the center of
the ellipse, where it crosses the line A. This point must not be
confounded with the _focus_. In a circle the focus is the exact center
of the ring, but there is no such thing in an ellipse. Instead, there
are two focal points, called the _foci_, as you will see presently.

Third. Step off two points or marking places, as we shall term them,
equidistant from the line B, and marked C, C. These marks will then
represent the diameter of the ellipse across its major axis.

Fourth. We must now get the diameter of the minor axis, along the line
B. This distance will depend on the perspective you have of the figure.
If you look at a disk at an angle of about 30 degrees it will be half of
the distance across the major axis.

So you may understand this examine Fig. 114. The first sketch shows the
eye looking directly at the disk 1. In the second sketch the disk is at
30 degrees, and now the lines 2 2, from the eye, indicate that it is