The disposition of the branches, like the anatomy of the human figure, is a matter of the greatest importance, de manding much study, in so far as every species has, in this respect, a different character and conformation ; whereas the single system of human anatomy enables us to dispose all the varieties of our figures. With trees, however, each has its distinct anatomy, an accurate knowledge of which is a rare acquisition, but an important one for a landscape painter. The due balance and quantity of clothing, pro portioned to the supporting arms, the disposition of all trees to supply the requisite balance, and counteract the tendency of stem, of position, of the prevailing wind, &C. require attention ; the arrangement of branches ought to be such as to show, that, if we could go round the tree, we should still find the balance preserved ; some branches advance direct to the eye, and seem to overhang the frame, while others recede into the interior of the picture ; and withal a seeming chance ought to appear to rule su pretne.
For a landscape painter the study of nature alone will not suffice, and that of the great masters will point out many things to which the uninstructed eye would prove a delusive guide. The illusions of vision are in every re spect remarkable, and in none more than in the miscon ceptions of landscape. We seem to see colours, because we know them to exist. Forms arc definite, and lines are straight, which the eye unconsciously sees far otherwise; so that, when represented as such, they are unpleasing, we know not why. Again, the degradation of distance is at constant variance with our pre-existing knowledge of the real magnitude of objects; and it comes to be a ques tion of some difficulty, to determine whether a painter ought to be guided by the real size and nature of objects, as geometry proves them to be, and as we set them repre sented by the camera lucida ; or to represent nature as we seem to sec it, modified by our habits, by the influencing circumstances of light and vapour, and by all the delusions of vision.
In enumerating the requisite attainments of the land scape painter, we cannot pass over that most indispensa ble of all, a knowledge of perspective, although this is not the place for a minute discussion of that important sub ject. Its application extends to every branch of painting as well as to landscape, as there is no object in nature which presents itself to our view, not even the clouds, that is not subject to the principles of perspective, which, in so far as regards the outline, is called linear ; and, when applied to the degradation of size, colour, and distinctness of objects by distance, is called aerial. It is surprising bow frequently we find artists of great merit shipwreck their fame on this rock, by neglecting the unyielding truths of perspective. A painter at least to be suf
ficiently acquainted with the rules, to be able to prove his accuracy in any doubtful point ; for in general such is the truth of a well trained eye, that it instantly detects the minutest deviation from correct perspective. From the charm of perfect truth in the compositions of most of the great masters, it is easily discoverable how profoundly skilled they were in the principles of this science. And in others, on the contrary, the deficiency is quite obvious; from the negligent practice of grouping their figures at random as imagination suggested, and adjusting them as they proceeded, instead of previously establishing a dis tinct standard of perspective, and degradation of size, serv ing to regulate every object as it took its place on their canvas. Due regard must at the same time be had to the proposed position of the eye of the observer. Nothing leads more unavoidably into error, than the practice of first painting the subject, and then adding the accessaries of architecture, or whatever species of filling up the sub ject may require. It is a chance that they do not recipro cally destroy the merits of each other, by a disregard of sonic essentials in proportion and perspective. There is no surer method than to form little models of clay of the figures desired; to be placed to the height of the eye, and exactly opposite to the point of sight ; removed at three times the intended breadth of the picture, where the group must be accurately drawn in the proportions which the figures respectively bear to each other. This forms a sure guide to the after-painting of the picture, and to the regulation of the exact position of any large studies made for it.
The nature of aerial perspective does not admit of its being subjected to equal precision of rules, being mate rially governed by the actual state of the atmosphere ; still an accurate observance of it is not the less indispensable. The effect of vapour produces a multitude of optical illu sions, which a landscape painter must study. When aug mented to the density of fog, they become exceedingly striking, and under that influence helve been admirably re presented by the French painter Vernet. Claude de Lorraine was likewise a great master of this art, par ticularly in the representation of haze as affected by the rays of the sun. Objects ih a fog appear greatly larger than usual. But a more perplexing illusion takes place, from the circumstance of near objects being, by the inter vention of vapour, rendered apparently at a greater dis tance, while at the same time they retain their magnitude. By being thus removed in appearance to a greater dis tance, without any alteration in the linear perspective, while the aerial is so much affected, they naturally assume the appearance of distant objects of great size.