the two pictures, or, generally speaking, which will give the best view of the mechanism, and then adjust the lenses of the camera to give the desired representations of it. These observations will be found useful in obtaining stereoscopic views of the structures in carpentry and shipbuilding.

CHAPTER XII.

APPLICATION OF THE STEREOSCOPE TO NATURAL

HISTORY.

such as

IN treating of those objects of natural history which enter into the composition of landscape scenery, trees, plants, and rocks, we have pointed out the method of having them accurately drawn for the stereoscope; but it is to the importance of stereoscopic photography in natural history as a science that we propose to devote the present Chapter.

When we reflect upon the vast number of species which have been described by zoologists, the noble forms of animated nature, whether wild or domesticated, and the valuable services which many of them perform as the slaves of man, we can hardly attach too much importance to the advantage of having them accurately delineated and raised into stereoscopic relief. The animal painters of the present day,-the Landseers, the Cowpers, and the Ansdells, have brought this branch of their art to a high degree of perfection, but the subjects of their pencil have been principally dogs, horses, deer, and cattle, and a few other animals, with which they are well acquainted, and specimens of which were within their reach.

To give

accurate representations of giraffes, hyænas, and the rarer animals which are found alive only in zoological gardens and travelling caravans, is a more difficult task, and one which has been necessarily intrusted to inferior hands. In this branch of his art the photographer is perplexed with the difficulty of arresting his subject in a position of repose and in the attitude which he requires. But this difficulty will diminish as his materials become more sensitive to light; and means may be found for fixing, without constraint, certain animals in the desired position. We have seen the portrait of a dog taken with such minute accuracy that the slightest trace of any motion could not be perceived. Its master directed his attention to a piece of bread, and he stood firmly waiting for his reward. Considering truth as an essential element in all photographs, we are unwilling to counsel the artist to have recourse to a large lens for the purpose of accelerating his process by seizing his restless object in a single instant of time; but what cannot be tolerated in the human form may be permitted in animal portraiture as a necessary evil. The divine lineaments and delicate forms which in man the intellect and the affections conspire to mould, are concealed under the shaggy drapery of the world of instinct; and even if they existed and were perceived, could hardly be appreciated by those who have not studied its manners and submitted to its laws. But even in the present state of photography such a celerity of process has been attained that a distinguished amateur in Edinburgh has constructed a portable camera, which, by pulling a trigger, instantaneously records upon its sensitive retina the surf which is hurrying to the shore, or the stranger who is passing in the

street. With such an instrument, in such hands, the denizens of the jungle or of the plains may be taken captive in their finest attitudes and in their most restless moods. Photographs thus obtained will possess a value of no ordinary kind, and when taken in the binocular camera and raised into relief by the stereoscope, will be valuable auxiliaries to the naturalist, and even to the painters and the poets whose works or whose lyrics may require an introduction to the brutes that perish.

In representing with accuracy the osteology and integuments of the zoological world—the framework which protects life, and to which life gives activity and power, the aid of the stereoscope is indispensable. The repose of death, and the sharp pencil which resides in the small lens, will place before the student's eye the skeleton, clothed or unclothed, in accurate perspective and true relief, while he contemplates with wonder, in their true apparent magnitude, the gigantic Mastodon, the colossal Megatherion, and the huge Dinornis, or examines the crushed remains of the lengthened Saurian, or the hollow footsteps which ancient life has impressed on the massive sandstone or the indurated clay.

In the other branches of natural history, ichthyology, ornithology, conchology, &c., the stereoscope will be found. equally useful. In entomology, where insects are to be represented, the microscopic binocular camera must be used; and in order to prevent the legs, the antennæ, and other small parts of the object from being transparent, and therefore spotted, with the images of objects or parts beyond them, as explained in a preceding chapter, the smallest lenses should be employed.

The roots and bulbs which are raised by the agriculturist and the horticulturist, the turnip, the beet, the carrot, and the onion; and the fruits raised in the orchard, on the wall, or in the hothouse, may be exhibited in all their roundness and solidity in the stereoscope; and as articles of commerce they might be purchased on the authority of their pictures in relief. The microscopic stereoscope will, in like manner, give accurate magnified representations in relief of grains and seeds of all kinds, and by comparing these with the representations of those of a standard form and quality, the purchaser may be enabled to form a better idea of their excellence than if he saw them with his own eyes, or had them in his own hands.