18. On these principles were founded the apparatus of Desault, and his process of reduction, which consisted, 1st, in drawing the arm forward, and separating the elbow a little from the thorax; 2dly, in fixing the fore-arm at an angle sufficiently acute, to direct the hand to the point of the opposite shoulder; and 3dly, to bring afterwards into proper apposition and form, the fragments already approximated to each other by the first movements. 19. To retain this reduction, the arm and fore-arm must be permanently fixed in the above position. This object is attained in the following manner, 1st, A bolster in form of a wedge, being placed between the arm and the side, its apex situated in the arm-pit, affords the double advantage of keeping the elbow at a distance from the thorax, and of rendering the position of the arm less fatiguing by serving as a point of support to it. 2dly, Compresses wet with some discutient liquid, are applied on the part corresponding to the fracture. 3dly, The whole is now to be secured by a roller, seven or eight yards long. The first turns of this roller, must secure the hand of the affected side on the sound shoulder to which it had been applied, during the reduction, and running afterwards from before backwards, pass over the place of the fracture, for the purpose of retaining the compresses on it. The wedge-formed bolster is to be secured on the thorax, by circular turns around it. Then, passing under the sound arm-pit, after having made these circular turns, the roller must be brought behind again, conducted obliquely over the shoulder of the diseased side, along the anterior part of the arm, under the elbow, and behind the thorax, where it is carried obliquely, in order to pass again under the sound arm-pit. From this place it ascends again anteriorly over the affected shoulder, redescends along the posterior part of the arm, repasses under the elbow, returns under the arm-pit, and terminates finally in circular turns round the trunk, and arm together. Hence it may be observed, that, in the first turns of the roller, this bandage greatly resembles the third roller applied in the fracture of the clavicle, to retain the point of the shoulder upward and backward (Fig. 4. plate I.)