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70 why artists have never succeeded in constructing statues which would stand without a pedestal, and such would also be the case in the human conformation were it not for the action of the muscles by which the spine is supported.

As we have already described, the clavicles or collar-bones exercise considerable influence in expanding the shoulders and chest; and this is an essential provision, for the purpose of counteracting the traction of the pectoral muscles, or those of the chest, whose tendency is to pull the shoulders forward, and by their action diminish the size of the thoracic cavity. The clavicles, however, would form but an insufficient means of accomplishing this end, were it not for the muscles of the back, which, when properly developed by exercise, neutralize the action of those of the chest, and keep the shoulders properly expanded. We lay a stress upon the necessity of exercise, for it must be remarked, that the greater its amount the greater the waste of substance, and the greater the quantity of blood carried to the wasting organ for its repair; while, pro­vided the exercise has been moderately taken and properly conducted, the greater will be the strength of the muscles thus thrown into action. For the preservation of the erect position no less than five layers of powerful muscles are placed along the spine, many of them taking their origin from the back of the head, and being inserted into various pro­cesses of the vertebral column; and it is by their action, combined with the elasticity of the spine and its cartilages, that we are enabled to stand upright, and to perform all the varied movements of which the human form is capable. The power of the muscles is so accurately balanced, that, provided all be in a normal condition, no difficulty is experienced in maintaining the erect attitude for a very considerable time. The spine has also natural curves, which act as springs to diminish the concussions which the brain would receive in walking were it not for those curves and the elasticity of the intervertebral car­tilages. To use a familiar simile, we may liken the head to that of a hammer, which is placed on a straight stick or handle. Everyone knows that the surest way to fasten the head is to knock the handle on the ground, as the concussion drives it further in; so that, if the human head were carried on a straight support, similar concussions would be caused to the brain and other vital organs, to their serious if