But, however valuable photography has become to the artist, science has recently given him another important auxiliary. In order to make this available, he must employ a small pocket binocular camera, to take double pictures to be united in the stereoscope. His trees will thus exhibit the roundness of their trunks and stems, the leaves and branches will place themselves at their proper distance, and he will discover the reason of peculiar effects which in the plane photograph he has been unable to understand. Seeing that his own picture is to be upon a plane surface, I can hardly expect to convince the artist that he will obtain more information by reproducing the original in relief. It is a fact, however, beyond dispute, that effects are produced by the stereoscopic union of two plane photographs which are invisible in the single picture. These effects, which are chiefly those of lustre and shade, are peculiarly remarkable in Daguerreotype, and it is by no means easy to explain the cause. In a Daguerreotype, for example, of two figures in black bronze, with a high metallic lustre, it is impossible, by looking at the single picture, to tell the material of which they are made; but the moment they are united into stereoscopic relief their true character is instantly seen. In a Daguerreotype of Alexander and Bucephalus, portions of the figure seem as if shaded with China ink of a nearly uniform tint, but when seen in relief the peculiar shade entirely disappears. The stereoscopic combination of two surfaces of different intensities, though of the same colour, produces effects which have not yet been sufficiently studied. But, independently of these peculiarities, the artist will certainly derive more aid from his landscape in relief, and from the study of its individual parts, in their roundness and relative distances, than when he examines them in their plane representations. The shadows which the branches of leaves cast upon the trunks and stems of his trees he will be able to trace to the causes which produce them. Effects in outline, as well as in light and shadow, which may perplex him, will find an explanation in the relative distances and differences of apparent magnitude of individual parts; and, after becoming familiar with his landscape in relief, as it exists in Nature, he cannot fail to acquire new principles and methods of manipulation. Nature flattened upon paper or metal, and Nature round and plump, as if fresh from the chisel of the Divine sculptor, must teach very different lessons to the aspiring artist.