1. Man enjoys an advantage which nature has bestowed on but few of the quadrupeds, namely, a power of moving his upper extremities in every direction. The clavicle being a kind of arch placed between the breast and shoulder, forms a centre, moveable indeed but solid, for these motions, a part of which can no longer be performed, when this arch, in consequence of being broken, ceases to afford them a point of support. Hence it follows, that the fracture of this bone may be said to reduce the individual who sustains it, when considered in relation to its functions, to a level with that numerous division of animals that are destitute of clavicles. 2. Few diseases of the kind are more frequently met with than this. The natural curve of the clavicle, its situation immediately under the skin, the want of a support to its middle part, the great proportion of spongy substance which enters into its composition, the projection of the shoulder exposing it to the action of external bodies; all these circumstances concur in rendering the accident frequent, particularly among that class of men subject, from their occupations, to violent exertions of the upper extremities. Here then, more than in the generality of fractures, we should feel an interest in the advancement of the art of surgery; and yet, having hitherto employed in it but feeble means, our efforts have been attended with imperfect success. Hippocrates has observed, that some degree of deformity almost always accompanies the reunion of a fractured clavicle; all writers since his time have made the same remark; experience has confirmed the truth of it, and as much time has been spent in hypothetical speculations to explain the accident, as in serious inquiries how to prevent it. At length Desault proved that a feeble and unskilful mode of treatment was the sole cause of a want of success, and that, by being more correct and judicious, art might be as successful here, as in other fractures. In order to give a correct view of his practice in this disease, I will examine the causes, varieties, and signs of a fracture of the clavicle; the accidents of which it is susceptible; the mode and the causes of the displacement of the broken ends of the bone; the indications that arise out of those causes, and the manner of answering these indications as well during, as after, the reduction. § II. OF THE CAUSES AND VARIETIES. 3. The action of external bodies is almost the only known cause of this fracture, whether these bodies strike the shoulder with violence, or the shoulder be forcibly driven against them. But this action is not in every case the same; its application is most frequently mediate or indirect, but is sometimes immediate or direct.