The Artist's Repository, Or, Encyclopedia of the Fine Arts (Band 2): Perspective, Architecture (London, 1808)

$0 on perspective. [lect. 1,

nations of axiom, theorem, corollary, or,
Q. E. D.

In looking down the regular and ftrait ftreets as we
pafs along this great city, we may obferve, and ap-
propriate to what has been our fubject, the planes
around us: the pavement is undeniably the ground
plane; in that part of another ftreet which croffes the
end of the ftreet down which we look, is the center
of the horizontal line : the fronts of the houfes on each
fide of the ftreet, form vertical planes; and as the
ground plane, by its continual apparent rifing, feems
to feek a union with the horizontal line, fo thefe ver-
tical planes, by appearing to approach clofer and
clofer, as their diftance from the eye increafes, appear
perpetually to feek a union with the vertical line, and
efpecially with the center, or direct beam of vifion
which regulates the whole.

I conceive the whole fcience, and fecret, of Per-
fpective is now opened; whatever variations may
happen, or indeed can be contrived, may be reduced
ultimately to thefe principles : I mail therefore detain
you but little longer, on this part of the fubject, while
I notice what, perhaps, may to fome perfon or other,
and at fome time or other, prove of fervice, if not of
importance.

From the nature of the vifual rays, I infer, that the
misfortune of a caft in the eye, arifes from the obli-
quity, and declination, of the center beam of one
eye caufed by the unequal ftrength of the eyes, whereby
one fboots, as it were, its beams well, the other with
infirmity ; now as this is regulated very much by the
*■ lituation