n at _O_, and from
_O_ draw lines to the several divisions on base line. These lines will
divide the vanishing line _DV_ into the required number of parts equal
to _DC_, the side of the square. Produce the diagonal of the square _DB_
till it cuts the horizon at _G_. From the divisions on line _DV_ draw
diagonals to point _G_: their intersections with the other vanishing
line _AV_ will determine the direction of the cross-lines which form the
bases of other squares without the necessity of drawing them to the
other vanishing point, which in this case is some distance to the left
of the picture. If we produce these cross-lines to the horizon we shall
find that they all meet at the other vanishing point, to which of course
it is easy to draw them when that point is accessible, as in Fig. 121;
but if it is too far out of the picture, then this method enables us to
do without it.

Figure 121 corroborates the above by showing the two vanishing points
and additional squares. Note the working of the diagonals drawn to point
_G_, in both figures.

LXI

FURTHER USE OF THE MEASURING POINT O

Suppose we wish to divide the side of a building, as in Fig. 123, or to
draw a balcony, a series of windows, or columns, or what not, or, in
other words, any line above the horizon, as _AB_. Then from _A_ we draw
_AC_ parallel to the horizon, and mark thereon the required divisions 5,
10, 15, &c.: in this case twenty-five (Fig. 122). From _C_ draw a line
through _B_ till it cuts the horizon at _O_. Then proceed to draw the
other lines from each division to _O_, and thus divide the vanishing
line _AB_ as required.

[Illustration: Fig. 122 is a front view of the portico, Fig. 123.]

[Illustration: Fig. 123.]

In this portico there are thirteen triglyphs with twelve spaces between
them, making twenty-five divisions. The required number of parts to draw
the columns can be obtained in the same way.

LXII

ANOTHER METHOD OF ANGULAR PERSPECTIVE, BEING THAT ADOPTED
IN OUR ART SCHOOLS

In the previous method we have drawn our squares by means of a
geometrical plan, putting each point into perspective as required, and
then by means of the perspective drawing thus obtained, finding our
vanishing and measuring points. In this method we proceed in exactly the
opposite way, setting out our points first, and drawing the square (or
other figure) afterwards.

[Illustration: Fig. 124.]

Having drawn the horizontal and base