ies of the engineering mind.

[249] I cannot waste space here by reprinting what I have said in other
books: but the reader ought, if possible, to refer to the notices of
this part of our subject in "Modern Painters," vol. iv. chap. xviii.,
and "Stones of Venice," vol. iii. chap. i. Sec. 8.

[250] If you happen to be reading at this part of the book, without
having gone through any previous practice, turn back to the sketch of
the ramification of stone pine, Fig. 4. page 30., and examine the curves
of its boughs one by one, trying them by the conditions here stated
under the heads A. and B.

[251] The reader, I hope, observes always that every line in these
figures is itself one of varying curvature, and cannot be drawn by
compasses.

[252] I hope the reader understands that these woodcuts are merely
facsimiles of the sketches I make at the side of my paper to illustrate
my meaning as I write--often sadly scrawled if I want to get on to
something else. This one is really a little too careless; but it would
take more time and trouble to make a proper drawing of so odd a boat
than the matter is worth. It will answer the purpose well enough as it
is.

[253] Imperfect vegetable form I consider that which is in its nature
dependent, as in runners and climbers; or which is susceptible of
continual injury without materially losing the power of giving pleasure
by its aspect, as in the case of the smaller grasses. I have not, of
course, space here to explain these minor distinctions, but the laws
above stated apply to all the more important trees and shrubs likely to
be familiar to the student.

[254] There is a very tender lesson of this kind in the shadows of
leaves upon the ground; shadows which are the most likely of all to
attract attention, by their pretty play and change. If you examine them,
you will find that the shadows do not take the forms of the leaves, but
that, through each interstice, the light falls, at a little distance, in
the form of a round or oval spot; that is to say, it produces the image
of the sun itself, cast either vertically or obliquely, in circle or
ellipse according to the slope of the ground. Of course the sun's rays
produce the same effect, when they fall through any small aperture: but
the openings between leaves are the only ones likely to show it to an
ordinary observer, or to attract his attention to it by its frequency,
and lead him to think what this type may signify respecting the