The second blade will be guided in its direction by that of the first: it must be introduced so that the inner surface of its handle corresponds exactly with that of the first. The locking must be performed under the same precautions as with the straight forceps: the more so, as in some cases it has to take place just within the os externum, and therefore requires the most careful attention to prevent the soft parts from being caught and pinched between the blades when they are brought together. In extracting the head we must bear in mind the part of the pelvis in which it is impacted, and make our effort in the direction of its axis; we must also recollect the curved form of the instrument, and that we must not pull in the direction in which the handles point, but rather hold them firmly with one hand, and, by pressing against the middle of the forceps with the other, guide the head downwards and backwards into the cavity of the pelvis. We shall thus make our extractive effort in the direction of the upper portion of the blades, or that part which has the chief hold upon the head: hence, therefore, as it descends, the handles are directed more and more forwards, so that when it has reached the perineum, the handles will not only point forwards, but considerably upwards. Whilst extracting we should, as with the straight forceps, slowly move the handles from side to side, and even make them describe a circle: we thus not only use the forceps as a simple extracting instrument, but make it act as a lever in every direction, and greatly facilitate the advance of the head, even under circumstances of considerable impaction. It is in these cases where keeping up a continued pressure upon the head by tying the handles tightly together, and tightening it after every successive effort, has such excellent effects in diminishing the degree with which it is wedged against the pelvis and soft parts, and in disposing it by gradual elongation to assume a form which is better adapted for advancing through the passages. The slow and gradual pressure of the forceps thus exerted upon the head of a living foetus will have a very different result to that of the experiments by Baudelocque and others, in attempting to compress the head of a dead foetus by the application of a sudden and powerful force. Even if we were capable of effecting no greater diminution of its lateral diameter than a quarter, or at the most, three-eighths of an inch, as stated by Dr. Burns, we should, in most cases of impacted head, where the forceps is justifiable, find it quite sufficient to remove the obstructing causes.