But it must be observed that in drawing the joints, very considerable difference is found in their length, from inequality of action. The elbow joint, when bent inward, lengthens the arm nearly one eighth; the same general law operates on the knees, fingers, &c. When a man is at rest, and standing on both feet, a line drawn perpendicularly between the clavicles will fall central between his feet. Should he stand on one foot, it falls upon the heel of that foot which supports his weight. If he raises one arm, it will throw as much of his body on the other side as nature requires to support the equilibrium. One of his legs thrown back brings the breast forward, to preserve the gravity of the figure: the same will be observed in all other motions of the parts to keep the central gravitation in its proper place. The equipoise of a figure is of two sorts: simple, when its action relates to itself; and compound, when it refers to a second object. The equilibrium of nature is constantly preserved; for in walking, leaping, running, &c., similar precautions are taken. By the flexibility of our bodies in striking, according to the proportionate force meant to be employed, the body is first drawn back, then the limb propelled forward, bringing with it the weight of the body. In striking, lifting, throwing, &c., a greater proportion of force is employed than may be necessary to effect the intended purpose. This is mentioned because, in representation, the force employed in an action should be marked in the muscle producing that action; if it be marked rather stronger than may be necessary, the cause is obvious, for Nature so employs her powers. In studying this art, students should have selected for them the best examples to copy from at first; then they should draw from the figure as soon as possible, and if it be possible from the best specimens of the antique. Their first drawings are recommended to be made with chalk, and in large proportion; attention to these will communicate ease and freedom to their future performances. It will be likewise found necessary for them to draw upon geometrical principles; this communicates a truth, which greatly adds to their certainty and confidence, and ultimately to their ease. This is mentioned, because it will be found that there is no portion of the human frame, quiescent, or in an active state, but what is susceptible of geometrical definition. Experience and exercise communicate truths which produce certainty, whence come ease and grace. ARCHITECTURE.