23. It was this which, in certain cases, induced Desault to place his counter-extension under the armpit, by means of a strap passing, as in the luxation of the humerus, over a ball previously fixed in this hollow, and crossing, not on the top of the opposite shoulder, but behind that of the diseased side. By this contrivance the humerus was drawn or rather held back, by a force acting perfectly in the line of its direction. But is not this force situated too near to the centre of motion? The strap for making extension, fastened at the wrist, answers very well, as has been already mentioned (21). 24. Should the luxation be forward, the extension must be directed according to the state and position in which the fore-arm is found, which is always extended. The hands of assistants alone (19), or straps (21), may then serve to make the extension, which the surgeon must aid, by grasping, in a direction the reverse of that in the preceding case, the lower extremity of the humerus, that is, by crossing his fingers behind, and placing his thumbs on the coronoid apophysis, to push it downward and backward. 25. The strap for counter-extension, would in such a case, always afford the greatest advantage, by being placed exactly as in luxations of the humerus, that is, by running to, and crossing on, the opposite shoulder; the direction or course of the fore-arm, which is necessarily in a state of extension, sufficiently explains this; finally, the reduction of the luxation must be succeeded by the reduction of the olecranon (5), and by the application of a proper apparatus to retain the whole. 26. The reduction of lateral luxations, differs but little from that of luxations backwards. The displaced extremities must be first dislodged by previous extension (19). The surgeon, then, taking hold of the lower part of the arm, places his fingers before, and with his thumbs, crossed on the olecranon, pushes that apophysis forward and inward, if the displacement be outwardly, but forward and outward if it be inwardly. Does the case prove very difficult, recourse must be had to the other means (21 and 23). The hands of the surgeon must still, according to the direction of the displacement, assist the extension made by the straps. § V. OF THE MEANS OF MAINTAINING THE REDUCTION. 27. Luxations of the fore-arm have, oftentimes, a great disposition to occur anew, after having been reduced, whether they be recent, or of long standing. Extension readily dislodges the olecranon and the radius, and replaces them perfectly in their natural situation; but if any thing interrupt them, the displacement is sometimes immediately renewed: suppose the parts even remaining in contact, the slightest motion may derange this contact, and give rise to a necessity for a new reduction, more difficult, oftentimes, than the first. Hence it is always prudent to employ a retentive apparatus for some time.