Thus the side of the model is
shown in Fig. 19, the end in Fig. 17; the two together give the precise
size and proportions of everything outside to scale, except the
projection of the pilasters. This has to be got at from the plan and
section. Everything being drawn on one plane, of course surfaces which
are sloping on one elevation are represented as flat in the other. For
instance, on No. 17 the raking line of the sloping roof is shown at N.
So we know the slope of the roof, but we do not know to what length it
extends the other way. This is shown on Fig. 19, where the portion
showing the roof is also marked N, and it will be seen that the surface
which is sloping in Fig. 17 is seen in the side elevation only as a
space between a top and bottom line. We see the length of the roof here,
and its height, but for its slope we go to the end elevation. Neither
elevation tells us, however, what is inside the building; but the
section (Fig. 18) shows us that it has an arched ceiling, and two
stories, a lower and a higher one. The section is the building cut in
half, showing the end of the walls, the height and depth of the window
openings, the thickness of the floor, etc., and as all parts which are
opposite the eye are shown in the drawing, the inside of the cross wall
at the end of the building is shown as a part of the section drawing,
between the sectional walls.
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