The first is to check hæmorrhage. Pressing with a firm pad on the external iliac just as it passes the bone, he must be prepared, the instant the anterior flap is cut, to follow the knife and seize flap and artery in his hand, and he is to hold it there till all the vessels in the posterior flap are first tied. The second has to manage the limb, and on the manner in which he performs his duty much of the success and nearly all the celerity of the operation depend. While the surgeon is transfixing the anterior flap, this assistant is to support the limb in a slightly flexed position, so as to relax the muscles; the instant the flap is cut he is to extend the limb forcibly, and at the same time be careful not to abduct it in the least, but to turn the toes inward so as to bring the great trochanter well forwards on a level with the joint; if this precaution is neglected, the operator in making the posterior flap is almost certain to lock his knife in the hollow between the head of the bone and the great trochanter. If it is the left side, the operator, standing on the outside of the limb, enters the point of a long straight knife midway between the anterior superior spinous process of the ilium and the great trochanter, and passes it as close to the front of the joint as possible, making the point emerge close to the tuberosity of the ischium (Plate IV. fig. 20-20). With a rapid sawing movement he then cuts a long anterior flap, avoiding any pointing of it, and endeavouring to make the curve equal. The fingers of the assistant must be inserted so as to follow the knife and seize the vessel even before it is divided. The flap being raised out of the way, the surgeon, without changing his knife (as used to be advised), opens the joint, divides the ligaments as they start up on the limb being extended and adducted, the round ligament, and the posterior part of the capsule; and then getting the knife fairly behind both the head of the bone and the trochanter, cuts the posterior flap as rapidly as possible. Instantly on the limb being separated, assistants should be ready with large dry sponges or pads of dry lint to press against the surface of the posterior flap, till the large branches, chiefly of the internal iliac, which are cut in it, are tied one by one. The lever invented by Mr. Richard Davy, by which the common iliac is compressed from the rectum, has in many cases proved of great service in preventing hæmorrhage, but has dangers of its own in cases of abnormal position of rectum, or even in sudden movements of the patient.