the deposit of vegetable matter. The first gross deposit having subsided, and been removed, an adequate quantity of salt was infused, to give the saltness of sea water; but after many days of trial, no change appeared to be produced in the green colour of the water of the Canal. To ascertain also generally the proportion of vegetable to other materials, I took the deposit of river waters, from a cistern which received them, and having dried it, I weighed a dram of the dry deposit, and having exposed it to the action of a red heat communicated to it during five minutes, found that it had lost 14 grains in weight, which taken at 12 allowing to accident the difference of loss, gives of the whole for the quantity of vegetable, mixed with other alluvial matter remaining, after a more speedy deposit of grosser materials to colour the seas of coasts, until discharged by time, and extin guished by extreme dilution in remote distances from land.

Wonderfully inaccurate is the observation of persons in general respecting these colours. They cannot but perceive the green colours of the seas of the coasts, as differing from those of other waters; but of the colours of other waters, what they really are, that they differ at different times from themselves, and how they differ, nothing is noticed. Even of water lying in present prospect, the colours are rarely observed until the attention is expressly called to and excited by naming them, and then indeed assent and admiration follow, alike establishing the truth and the novelty of the sight. I have frequently observed upon the beauty of the waters of a river in the prospect, to persons looking upon a particular scene. Then gently averting the person, I have enquired what is the colour of the water just seen? The answers have been, why-the colour of water. Is it red? No. Is it blue? No. Look round. The colour is a most brilliant blue.

Philosophers have not been more observant of these particulars. Painters alone have been practically led to observe their appropriate colours, in order that they may represent waters among other objects, and of those who correctly have painted from nature, the representations are illustrative of these principles. These principles indeed they have not possessed; but the principle of imitation and the necessity of observing has in many

cases secured them from error. With these principles, assisted by those of imitation and selection, the most brilliant exhibitions

may be expected.

A painting by Rembrandt called the Windmill, belonging to W. Smith, Esq. M. P., and exhibited in the British Gallery in 1815, gave occasion to a conversation which induced the present communication.

A river winding round the base of a high bluff of land on which the mill stands, reflects the light of an atmosphere brilliantly white down to the horizon. The river of course is white, with scarcely any other mixture of colour.

I asked sportively of two gentlemen, philosophers of eminence, standing below it, and conversing in the room, what were the colours of seas, lakes, and great rivers; and limiting my question to seas, was answered by one-green, a mixture of yellow; by the other, the colours of Vandervelde's Sea Pieces, naming and referring to them in the other room. I stated, according to the foregoing principles, that I had seen seas and waters of all the prismatic colours; seas blue, green, yellow, red; seas of quicksilver, of molten gold, of blood; waters that were black, that were white ; and to that I refer you, pointing to the picture, and adding, as in the story of the cameleon, "produced the Beast, and lo! 'twas -white."

coast.

I was further led to examine the waters of the Exhibition, as represented by several masters. In Rubens's Duke of Buckingham, belonging to the Earl of Jersey, the colour of the sea is a dirty green, very much resembling the green water seen immediately from below the bridge of the Canal, not so dilute as the seas of the Of Vandervelde the waters may be said to have no natural colours at all, scarcely more than the lights and shades of engravings. Cuyp's colours are such as a day of sunshine thickly overspread with masses of white and dark clouds gives to waters. This gravelly colour, which may be either external by reflection, or internal from turbid waters, Cuyp gives to his waters of Dort, with no green; and little blue.

I have stated that the colours exhibited at the surfaces of water are reflected by the air incumbent on the water, VOL. V.

H

and not by the water, which is incapable of reflecting light from or by its surface of external incidence. The general and philosophic misconceptions on this point require here to be observed upon. The existence of any power in bodies to repel light, has been formally and completely disproved by observations on the inflections of light. Light is attracted by the parts of all bodies. This is sometimes admitted and sometimes denied by observers, even to the same bodies in various circumstances. If light pass out of glass into air, and particularly when the reflection is total, this is ascribed to the glass; if partially, the reflection is assigned to the glass, the refraction to the air, by attractions of both. Let the light pass out of air into glass, both the reflection and refraction are ascribed to the glass, and in similar circumstances to water. This reasoning ascribes to the glass in this latter case, powers opposite to and inconsistent with those of the former case, and deprives the air of all the power in the first instance assigned to it. The air not being seen, nor so obvious as the glass, seems in this case forgotten or disregarded, and such is the state of general opinion on this subject.

At the confines of two adjacent transparent bodies, one of which at least must be fluid, spaces naturally exist different from the pores of either, in consequence of the attractions of the particles of both being different, as well as stronger for themselves than for each other; otherwise one would be dissolved by the other, as chemists know. In these spaces the bodies by their respective attractions for light, divide whatever portion thereof arrives therein into two parts, one passing into and said to be refracted by the further; the other returning into, and said to be reflected by the nearer body. The nearer body can alone reflect, the further alone refract; and these are the cases of air and water in these observations. In these same spaces, and by the same attractions in other circumstances, the emission of light is produced. That these forces exist, and that by them the phenomena of the emission, reflection, and refraction of light are produced, may be proved

by arguments of the same nature and force, as those which prove the moon to be retained in her orbit by the force of gravity, by proofs establishing the existence, adequacy, and quantity, and therefore necessary agency of these forces.

ART. XII. On the original Composition of the Statues of Niobe and her Children. By Robert Cockerell, Esq. THE statues composing the groupe of Niobe and her Children

has long been considered amongst the first specimens of art. If all the figures were not executed by the same hand, their style and composition leave little doubt that they were the conception of one mind: they are obviously designed to form a whole, but placed without order or design as they were, and still remain, the figures appear without connection, and to act rather in opposition to each other, than as forming a combined action or connected groupe, and they can only be regarded in their present position as single figures, without reference to their combined effect. None of the antiquarians who have noticed these statues, (including Winckelman, Fabroni, Mengs, Goethe, and Zannoni), have attempted to solve this difficulty. Mr. R. Cockerell, whose travels we noticed in a former Number, about two years since published in Italy a plate explanatory of his ideas respecting the composition of these statues, which represents, as he maintains, the fable of Niobe and her family. This plate was accompanied by a short explanation of Mr. Cockerell's reasons in support of his opinions respecting the original composition of these statues. Although Mr. Cockerell's merits seem to have but tardily reached his own country, neither his talents or his knowledge have remained unnoticed on the continent.

These statues are supposed by Mr. Cockerell to have been originally designed for the tympanum of a pediment of a temple, the elevation and measurement of which has been

given by him in his plate, a reduced outline of which we have, by his permission, given in this Number. We shall present our readers with nearly the whole of Mr. Cockerell's observations on the subject.

The celebrated statues representing the fable of Niobe, have never been so described as to give a satisfactory idea of their relative situations, and the composition of the groupe for which they were unquestionably designed.

Montfaucon (Vol. I. p. 107,) has given a plate engraved by Perier representing these statues, ranged in a circle around the mother, as they were then placed in the villa Medicis at Rome; but this disposition, which was a mere conjecture, and entirely unsupported by the authority of the ancients, or any one single example, is entirely disproved by examination of the statues themselves, and of their different attitudes, which demonstrate that they were originally intended for only one point of view,* * as will be seen from the note below, which describes the different sides of the statues.

* The statue No. 1, was designed solely for the position assigned in the group, for if viewed in the front, the right leg is rendered invisible by the rock which sustains it; besides which, the chest is without relief and ill executed. No. 2, on the opposite side the left leg is entirely concealed behind the rock, and the drapery suspended from the arm is but imperfectly made out. The back part of the statue No. 3 is also negligently executed and badly designed, without relief or execution. The hinder parts of No. 4, 5, 6, 7, and 8, although completely made out, are not better executed than the preceding numbers. No. 9, on the front side, the contour of the body, the hair, and the ear on the right side, are carefully finished; on the left they are merely sketched. The statue No. 10, is unfinished on the opposite side, and the right leg is concealed by a trunk of a tree. No. 11 and 12 are also left unfinished on the opposite side. No. 13: with respect to this figure, the point of view given is evidently the only possible one it could have been designed for, as the right leg is entirely wanting; and it is evident that Nos. 6, 7, and 9, were designed for a situation above the level of the eye, the different parts being more or less finished, according to the effect to be produced when seen from below.