its position, for it is evident that a near column must
appear wider than the opposite one. On the right of the figure is the
vertical scale _A_, which gives the heights of the columns, and at its
foot is a horizontal scale, or a scale of widths _B_. Now, according to
the line on which the column stands, we find its apparent width marked
on the scale. Thus take the small square and circle at 15, without its
column, or the broken column at 16; and note that on each side of its
centre _O_ I have measured _oa_, _ob_, equal to spaces marked 3 on the
same horizontal in the scale _B_. Through these points _a_ and _b_ I
have drawn lines towards point of sight _S_. Through their intersections
with diagonal _e_, which is directed to point of distance, draw the
farther and nearer sides of the square in which to describe the circle
and the cylinder or column thereon. I have made all the squares thus
obtained in parallel perspective, but they do not represent the bases of
columns arranged in circles, which should converge towards the centre,
and I believe in some cases are modified in form to suit that design.

CVII

COLUMNS AND CAPITALS

This figure shows the application of the square and diagonal in drawing
and placing columns in angular perspective.

[Illustration: Fig. 196.]

CVIII

METHOD OF PERSPECTIVE EMPLOYED BY ARCHITECTS

The architects first draw a plan and elevation of the building to be put
into perspective. Having placed the plan at the required angle to the
picture plane, they fix upon the point of sight, and the distance from
which the drawing is to be viewed. They then draw a line _SP_ at right
angles to the picture plane _VV'_, which represents that distance so
that _P_ is the station-point. The eye is generally considered to be
the station-point, but when lines are drawn to that point from the
ground-plan, the station-point is placed on the ground, and is in fact
the trace or projection exactly under the point at which the eye is
placed. From this station-point _P_, draw lines _PV_ and _PV'_ parallel
to the two sides of the plan _ba_ and _ad_ (which will be at right
angles to each other), and produce them to the horizon, which they will
touch at points _V_ and _V'_. These points thus obtained will be the
two vanishing points.

[Illustration: Fig. 197.
A method of angular Perspective employed by architects.
[_To face p. 171_] ]

The next operation is to draw lines from the princ