object, presents no difficulty for him to contend with. The struggle he has to maintain, is principally with that colour as it recedes from light and descends to shade; assuming in its progress many hues of diminished lustre, which vary with surrounding circumstances.

While I endeavour to explain to you my view of the theoretical principles of colouring in painting, I entreat you to confine your attention, as much as possible, to colours alone, independent of form. The shortest, and most efficient mode of learning any thing well, is by reducing it in the first place to its component parts, independent of its effects; and when those parts are understood, combinations of them may be made with comparative ease and security.

A considerable degree of difficulty arises in the discussion of this subject, from the want of a clear and distinct application of the terms we commonly employ when speaking of it. Hue, and tone, and tint, are often confounded; and contrast, is employed to signify, not only two colours placed together which have no affinity, or an imperfect degree of it, and consequently produce discordant effects upon the eye; but also, those appositions of colours which are the source of harmony; and produce an agreeable sensation to the eye, when placed beside each other.

It would render the matter much more clear to us, if, confining the word contrast to its strictest sense, we applied it only to the apposition of discordant colours; and termed the other varieties harmonies, or concords, to borrow another term from music. As to the word hue, I would confine it to the signification of the peculiar quality of each colour; that which distinguishes one from another; as red from blue, and blue from yellow, &c., throughout all their varieties and combinations. By tint, I mean the degrees of gradation of any one colour, from its extreme degree of intensity, to its faintest: and tone, I would attach only, to the effect produced by the degree and colour of the illumination, and the shadows it produces; and as this nomenclature suits my purpose, I shall therefore employ it.

Though colouring be multifarious in its qualities, extensive in its unions and effects, and difficult in its application, yet the principles on which it chiefly depends are simple.

If we take a round object, and expose it to a direct ray of light, having placed it out of the reach of reflection from the atmosphere, or any illumined body; we shall find its surface presenting to our view three points relative to colour. Its actual or proper colour, where the

light falls upon it; its shade where deprived of light; and the intermediate portion of it, which constitutes, in the language of the painter, its half tint; and which becomes gradually deprived of colour as it approaches to the deeper shadow.

Light, then, is the cause of colour; and a regulation of nature hitherto inexplicable to us; giving to different bodies the power of separating the component parts of the rays of light, and reflecting to our eyes some peculiar portions of them only; absorbing, or at least not reflecting the others, is the cause of the rich variety of hues we see around us.

Hence it follows, that the more fully illumined any coloured body may be by the common light of day, the more vividly will its colour be exhibited; and, on the reverse, the less the degree of illumination it receives, the more faint or dull will be the power of its colour; till at length, where no ray of light can fall upon its surface, it will be deprived of its colour entirely, and become black.

If, however, the coloured body be exposed to the intense light of the sun's direct ray, there is then formed another point for the consideration of the painter; which is, that in that portion of the plane of the coloured surface, which lies, with respect to the eye, at an angle

equal to that at which the rays of the sun descend upon the body, at that point, which is the seat of what we term the high light, there is reflected a certain quantity of the perfect light of the sun, or white; which destroys the colour in proportion to its own degree of intensity, by rendering it whiter than the general actual hue surrounding this bright light. This is rendered intelligible by referring to halfpolished substances, as silk, or satin, but it takes place more or less in all.

But for the present, I wish you to dismiss this consideration from your minds, and revert to the first proposition; viz. that coloured substances obtain their hues from light, and lose them when deprived of it. Connect this proposition with another, viz. that shade, abstractedly considered, is always alike in tone; and you then perceive, that the same tone of darkness, whatever be its degree, pervades all colours as they recede from light, to their complete union and total loss in shadow.

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We may arrive at the same conclusion by a more technical mode of proceeding; and, for the purpose of explaining it, I lay before you the ingenious diagram given in a work published many years ago, by Moses Harris, under the title of "The Natural System of Colours." In the circular portion of his diagram, the pris

matic colours, red, blue, and yellow, are united, consonant with the system of the rainbow, by orange, green, and purple; and all are graduated from the centre outwards, that is, from their utmost intensity, to the faintest tint approaching to white; and those tints are marked by a scale of strength, say twenty-five; supposing the five marked circular spaces to contain five degrees each.