56. The patient being properly situated, under the arm-pit of the affected side is placed the linen ball, on which the middle of the first strap is then applied. The two ends of this strap being now brought obliquely upwards, before and behind the thorax, so as to meet on the top of the sound shoulder, and being held by an assistant, serve to fix the body, and to make counter-extension, nor does the action of the strap bear on the edges of the pectoralis major and latissimus dorsi, in consequence of the ball which projects beyond their edges. Were it not for this, these muscles, being pulled upwards, would draw in the same direction the humerus, to which they are attached, and would thus destroy the effect of the extension, which is made in the following manner. 57. Two assistants take hold of the fore-arm above the wrist, or else a folded napkin is fixed on that part, having its two ends twisted around each other. These ends, thus folded together, are given to one or two assistants, who begin to pull in the direction of the humerus. To this first movement, intended to disengage the head of the bone from the bed which it occupies, another succeeds, which must vary according to the kind of luxation. If the luxation be downwards, the surgeon gradually approximates the arm to the trunk, at the same time that he pushes it gently upwards. By this process, the head of the bone, being drawn from the trunk, and brought towards the glenoid cavity, usually re-enters it with but little resistance. If the luxation be inwards, the extremity of the humerus, after extension according to the direction of the bone, should be carried upward and forward, in order that its head may be directed backwards. Steps the very reverse of these must be pursued, if a luxation in an outward direction is to be reduced. 58. In general, when, by the first extension, the head of the bone is disengaged, the motion communicated to it by the subsequent ones, ought to be in a direction precisely opposite to that which it pursued in escaping from its cavity. But what are the variations of this direction? Extensive experience alone can clearly determine this point. Without experience the practitioner works in darkness. The minutiæ or particulars of the process of reduction, being different in different cases and according to different circumstances, can be neither foreseen, nor taught by precept. 59. If the head of the bone experience any difficulty in re-entering its cavity, it is necessary, when the extensions have been made, to communicate to the bone different movements, varied according to the different directions of displacement, and regulated by the principle just established. Oftentimes this method effects what extensions alone cannot; and the head of the bone, carried by these movements towards its cavity, enters it while they are performing.