8. As the displacement is most likely to occur downwards, particularly in motions of the arm, it is necessary that a continued resistance be opposed to this tendency. But this resistance should be made by the head of the humerus, which, if properly directed, will represent, during the treatment, a kind of splint, which art ought to render fixt and immoveable lest, being contiguous to the divided surfaces, it might derange, by its motions, the work of nature in effecting their reunion. Hence it follows, that the precise and immediate intention of the whole apparatus destined to support fractures of the acromion apophysis, is, 1st, to keep the head of the humerus constantly elevated or pushed upwards: 2dly, carefully to prevent all motions of the arm and shoulder. 9. If the means, heretofore employed in this fracture, be examined, it will be perceived that they by no means fulfil this twofold indication. A compress placed immediately over the fracture; a roller passed round this to secure it; a ball or bolster[9] put into the hand; the fore-arm supported in a sling; such is the apparatus recommended by Petit. In addition to this, Duverney judiciously advises to keep the sling elevated, for the purpose of keeping the head of the humerus applied under the fractured pieces. He employed also the spica-bandage which has been equally recommended by Heister. [9] Une pelotte. 10. But, in the employment of these means, the arm, not being confined against the trunk, can move with ease, and derange the fragments, and, therefore, the second indication is not fulfilled. Will even the first be fulfilled? By no means. The sling, being soon deranged, by the movements of the arm, which are oftentimes involuntary, suffers it to sink down again, and then the fragments, being no longer supported, are displaced. Hence the difficulties attending the treatment, difficulties which have not escaped the notice of authors, and which Heister thus expresses: “_Nemo ita curari solet_, _ut brachium postea, liberi sursum attollere queat_,” an observation, which the celebrated Cheselden made before him, in describing the scapula. 11. These inconveniences will be avoided, by fixing the arm, as recommended by Desault, firmly against the trunk, by converting, so to speak, the arm and the trunk into one single and solid piece, in such a manner, that the humerus having no other motions but those in common to it and the thorax, may not be able to communicate any others to the fragments, which are supported by its head. This advantage can be easily obtained, by means of the bandage, already described, for fractures of the clavicle, modified agreeably to the circumstances of the case, in which it is to act.