If we wish to have a greater degree of relief than we have with our two eyes, either in viewing colossal statues, or buildings, or landscapes, where the deviation from nature does not, as in the human face, affect the expression, or injure the effect, we must increase the distance of the lenses in the binocular camera, or the angle of direction of the common camera. Let us take the case of a colossal statue 10 feet wide, and suppose that dissimilar drawings of it about _three_ inches wide are required for the stereoscope. These drawings are _forty_ times narrower than the statue, and must be taken at such a distance, that with the binocular camera the relief would be almost evanescent. We must therefore suppose the statue to be reduced _n_ times, and place the semi-lenses at the distance _n_ × 2½ inches. If _n_ = 10, the statue 10 feet wide will be reduced to ¹⁰/₁₀, or to 1 foot, and _n_ × 2½, or the distance of the semi-lenses will be 25 inches. With the lenses at this distance, the dissimilar pictures of the statue will reproduce, when combined, a statue one foot wide, which will have exactly the same appearance and relief as if we had viewed the colossal statue with eyes 25 inches distant. But the reproduced statue will have also the same appearance and relief as a statue a foot wide reduced from the colossal one with mathematical precision, and it will therefore be a better or more relieved representation of the work of art than if we had viewed the colossal original with our own eyes, either under a greater, an equal, or a less angle of apparent magnitude. We have supposed that a statue a foot broad will be seen in proper relief by binocular vision; but it remains to be decided whether or not it would be more advantageously seen if reduced with mathematical precision to a breadth of 2½ inches, the width of the eyes, which gives the vision of a hemisphere 2½ inches in diameter with the most perfect relief.[55] If we adopt this principle, and call B the breadth of the statue of which we require dissimilar pictures, we must make _n_ = B/2½, and _n_ × 2½ = B, that is, the distance of the semi-lenses in the binocular camera, or of the lenses in two cameras, must be made equal to the breadth of the statue. In concluding this chapter, it may be proper to remark, that unless we require an increased relief for some special purpose, landscapes and buildings should be taken with the normal binocular camera, that is, with its lenses 2½ inches distant. Scenery of every kind, whether of the picturesque, or of the sublime, cannot be made more beautiful or grand than it is when seen by the traveller himself. To add an artificial relief is but a trick which may startle the vulgar, but cannot gratify the lover of what is true in nature and in art. _The Single Lens Binocular Camera._