spersed through the whole
space of the sky, is necessary to this phenomenon; and secondly, that
what we usually think of as beams of greater brightness than the rest of
the sky, are in reality only a part of that sky in its natural state of
illumination, cut off and rendered brilliant by the shadows from the
clouds,--that these shadows are in reality the source of the appearance
of beams,--that, therefore, no part of the sky can present such an
appearance, except when there are broken clouds between it and the sun;
and lastly, that the shadows cast from such clouds are not necessarily
gray or dark, but very nearly of the natural pure blue of a sky
destitute of vapor.

Sec. 15. Erroneous tendency in the representation of such phenomena by the
old masters.

Sec. 16. The ray which appears in the dazzled eye should not be
represented.

Sec. 17. The practice of Turner. His keen perception of the more delicate
phenomena of rays.

Sec. 18. The total absence of any evidence of such perception in the works
of the old masters.

Now, as it has been proved that the appearance of beams can only take
place in a part of the sky which has clouds between it and the sun, it
is evident that no appearance of beams can ever begin from the orb
itself, except when there is a cloud or solid body of some kind between
us and it; but that such appearances will almost invariably begin on the
dark side of some of the clouds around it, the orb itself remaining the
centre of a broad blaze of united light. Wordsworth has given us in two
lines, the only circumstances under which rays can ever appear to have
origin in the orb itself:--

"But rays of light,
Now _suddenly_ diverging from the orb,
_Retired behind the mountain tops, or veiled
By the dense air_, shot upwards."

EXCURSION, Book IX.

And Turner has given us the effect magnificently in the Dartmouth of the
River Scenery. It is frequent among the old masters, and constant in
Claude; though the latter, from drawing his beams too fine, represents
the effect upon the dazzled eye rather than the light which actually
exists, and approximates very closely to the ideal which we see in the
sign of the Rising Sun; nay, I am nearly sure that I remember cases in
which he has given us the diverging beam, without any cloud or hill
interfering with