But your correspondent will say, “What does it matter to me, or to the artist, whether they are shadows or not? They are darkness, and they supply the place of shadows, and that it is all I contend for.” Not so. They do not supply the place of shadows; they are divided from them by this broad distinction, that while shadow causes uniform deepening of the ground-tint in the objects which it affects, these pseudo shadows are merely portions of that ground-tint itself undeepened, but cut out and rendered conspicuous by flashes of light irregularly disposed around it. The ground-tint both of shadowed and illumined parts is precisely the same—a pure pale gray, catching as it moves the hues of the sky and clouds; but on this, in the illumined spaces, there fall touches and flashes of intense reflected light, which are absent in the shadow. If, for the sake of illustration, we consider the wave as hung with a certain quantity of lamps, irregularly disposed, the shape and extent of a shadow on that wave will be marked by the lamps being all put out within its influence, while the tint of the water itself is entirely unaffected by it.
The works of Stanfield will supply your correspondent with perfect and admirable illustrations of this principle. His water-tint is equally clear and luminous whether in sunshine or shade; but the whole lustre of the illumined parts is attained by bright isolated touches of reflected light.
The works of Turner will supply us with still more striking examples, especially in cases where slanting sunbeams are cast from a low sun along breakers, when the shadows will be found in a state of perpetual transition, now defined for an instant on a mass of foam, then lost in an interval of smooth water, then coming through the body of a transparent wave, then passing off into the air upon the dust of the spray—supplying, as they do in nature, exhaustless combinations of ethereal beauty. From Turner’s habit of choosing for his subjects sea much broken with foam, the shadows in his works are more conspicuous than in Stanfield’s, and may be studied to greater advantage. To the works of these great painters, those of Vandevelde may be opposed for instances of the impossible. The black shadows of this latter painter’s near waves supply us with innumerable and most illustrative examples of everything which sea shadows are not.
Finally, let me recommend your correspondent, if he wishes to obtain perfect knowledge of the effects of shadow on water, whether calm or agitated, to go through a systematic examination of the works of Turner. He will find every phenomenon of this kind noted in them with the most exquisite fidelity. The Alnwick Castle, with the shadow of the bridge cast on the dull surface of the moat, and mixing with the reflection, is the most finished piece of water-painting with which I am acquainted. Some of the recent Venices have afforded exquisite instances of the change of color in water caused by shadow, the illumined water being transparent and green, while in the shade it loses its own color, and takes the blue of the sky.
But I have already, Sir, occupied far too many of your valuable pages, and I must close the subject, although hundreds of points occur to me which I have not yet illustrated[196]. The discussion respecting the Grotto of Capri is somewhat irrelevant, and I will not enter upon it, as thousands of laws respecting light and color are there brought into play, in addition to the water’s incapability of shadow.[197] But it is somewhat singular that the Newtonian principle, which your correspondent enunciates in conclusion, is the very cause of the incapability of shadow which he disputes. I am not, however, writing a treatise on optics, and therefore can at present do no more than simply explain what the Newtonian law actually signifies, since, by your correspondent’s enunciation of it, “pellucid substances reflect light only from their surfaces,” an inexperienced reader might be led to conclude that opaque bodies reflected light from something else than their surfaces.
The law is, that whatever number of rays escape reflection at the surface of water, pass through its body without further reflection, being therein weakened, but not reflected; but that, where they pass out of the water again, as, for instance, if there be air-bubbles at the bottom, giving an under-surface to the water, there a number of rays are reflected from that under-surface, and do not pass out of the water, but return to the eye; thus causing the bright luminosity of the under bubbles. Thus water reflects from both its surfaces—it reflects it when passing out as well as when entering; but it reflects none whatever from its own interior mass. If it did, it would be capable of shadow.
I have the honor to be, Sir,
Your most obedient servant,
The Author of “Modern Painters.”
[From “The London Review,” May 16, 1861.]
THE REFLECTION OF RAINBOWS IN WATER.[198]
To the Editor of “The London Review.”