11. Most of the symptoms formerly mentioned (5 and 6) as accompanying a fracture of the clavicle, are evidently the result of a displacement of its broken ends. Yet this phenomenon, taken notice of by all authors, and considered by them as a necessary effect of the disease, does not occur in every case (8). There are instances, in cases of transverse fractures, where the extremity attached to the shoulder, has retained its natural position. Three examples of this kind occurred in the Hotel-Dieu in the course of the year 1787. 12. Instances have also been known, in which the sternal fragment, when fractured obliquely upwards, has supported the end of the humeral in such a manner as to prevent any derangement. Desault was accustomed to relate several cases, where similar occurrences took place; but, in general, this state of things is rare, in comparison with that in which the fragments lose their natural level. Almost always, then, there is more or less of a perceptible overlapping (_chevauchement_) produced, either, by the elevation (a circumstance which is very rare) of the external fragment over the internal; or, (as commonly occurs) by the depression of the former beneath the latter. 13. Of the first of these modes of displacement (a mode but rarely mentioned by authors) a few examples are to be found among the observations of Desault, one of which he has recorded in his journal. Hippocrates speaks of the phenomenon as a thing that was familiar to him. 14. The second kind of displacement, that which we constantly find in practice, and which the laws of muscular action render almost inevitable, takes place in such a manner that the shoulder appears to obey the impulse of two powers, one of which draws it downwards, and along with it the external fragment of the clavicle, which is displaced by this power in the direction of its transverse diameter, or thickness. The other power approximates the shoulder to the breast, and draws it forward, carrying along with it the same fragment, which is by this means displaced in a longitudinal direction. That we may the better understand them and their effects, let us, in our minds, separate these two powers, although they are perfectly simultaneous in their action. A knowledge of them will lead us to a knowledge of the resistances which ought to be opposed to them. But let us first remark, that the humeral fragment, being drawn downward and inward, takes sometimes such a direction, that its internal extremity passes backward under the sternal fragment, its external end continuing to point forward: this disposition can be understood from its natural direction.