It has been shown (at pages 25 to 34) that the law of perspective, as commonly taught in our Schools of Art, is fallacious and contrary to everything seen in nature. If an object be held up in the air, and gradually carried away from an observer who maintains his position, it is true that all its parts will converge to one and the same point; but if the same object be placed upon the ground and similarly moved away from a fixed observer, the same predicate is false. In the first case the _centre_ of the object is the _datum_ to which every point of the exterior converges; but in the second case the _ground_ becomes the _datum_, in and towards which every part of the object converges in succession, beginning with the lowest, or that nearest to it. Instances:--A man with light trousers and black boots walking along a level path, will appear at a certain distance as though the boots had been removed, and the trousers brought in contact with the ground. A young girl, with short garments terminating ten or twelve inches above the feet, will, in walking forward, appear to sink towards the Earth, the space between which and the bottom of the clothes will appear to gradually diminish, and in the distance of half-a-mile the limbs, which were first seen for ten or twelve inches, will be invisible--the bottom of the garment will seem to touch the ground. A small dog running along will appear to gradually shorten by the legs, which, in less than half a mile, will be invisible, and the body appear to glide upon the earth. Horses and cattle moving away from a given point will seem to have lost their hoofs, and to be walking upon the outer bones of the limbs.