_Leather_ takes so much time to set that it should not be used in recent fractures. When the bone is partly set, leather is a useful substitute for wood. It is prepared from a pattern in the same manner as the gutta-percha, but is trimmed before soaking, not after it is moulded, like gutta-percha. If possible it should have twenty-four hours soaking in _water_ before being fitted to the limb; but when this cannot be done, immersion in hot water, into which a teacupful of vinegar has been thrown, will make the leather quite supple in a quarter of an hour. The leather splint must be worn twenty-four hours while it sets, and then be removed for covering (see Leather Splints). =Fractured Shaft of the Humerus.= _Apparatus._—1. Four straight hollow splints. 2. Rollers 2 inches wide, and 1 inch for the fingers, or straps and buckles. 3. Pads and wool. 4. Sling. When broken below the attachment of the deltoid and coraco-brachialis muscles the displacement of the bone is commonly prevented with ease; neither shoulder nor elbow-joint need be fixed, and it is not necessary to apply the splints so tightly as to risk interference with the venous circulation. If the pectoral muscles or deltoid be connected with the lower fragment, the displacement is sometimes obstinate; in such cases it is necessary to buckle the splints lightly. For this to be done, the fingers, hand, and forearm must be previously bandaged to prevent œdema; with this addition, the method of treatment is the same in both varieties of fracture. Step 1. Select the splints; they should be hollowed, of wood, perforated sheet zinc, or wire gauze, about 2 inches broad, lightly padded, and provided with straps and buckles. The external one reaches from the acromion to the outer condyle; the inner one from the axilla to the inner condyle; a third shorter one is placed behind the arm, and if there is much projection forwards of the lower fragment, a fourth very short one is added in front. The patient should sit on a chair while the apparatus is being put on. Step 2. The fingers and thumb are bandaged; then, the hand and forearm, first padded with a little wool in the palm and over the wrist, are evenly bandaged to the elbow, round which the roller is carried while the joint is well flexed; this being covered in, the roller is made fast. The first step of bandaging the hand and forearm before applying the splints is better omitted if the compression requisite to procure the natural position of the bone does not interfere with the circulation. Step 3. An assistant grasping the elbow in one hand, pulls down the lower fragment, while he steadies the shoulder with the other. The displacement thus reduced, the surgeon applies the splints, taking care that the inside splint does not reach too high into the axilla, lest it compress the axillary vein.