When the perforation has been made, it will be desirable to wait a few hours before making any attempt to extract: we thus give the mother an opportunity of getting a little rest; the attachments of the cranial bones after a short time become more yielding, the head collapses more readily, and adapts itself better to the form of the passages. "In all circumstances," says Dr. Osborn, "which admit and require precision, I would recommend the delaying all attempts to extract the child till the head has been opened at least thirty hours: a period sufficient to complete the putrefaction of the child's body, and yet not sufficient to produce any danger to the mother. From such conduct, the beneficial effects of facilitating the extraction of the child, I am firmly convinced, by frequent experience, will much overbalance any possible injury which may reasonably be expected from the putrid state of the child and secundines in so short a time. The propriety, however, of this delay entirely depends upon the head being opened in the beginning of labour: for if we do not perform the first part of this operation till the labour has been protracted so long as that the woman's strength begins to fail, we must expedite the delivery as speedily as possible, otherwise, the danger which we wish to avoid, will infallibly be incurred: no woman can suffer continued labour beyond a certain period without fever, inflammation, and the most imminent danger, if not death ensuing." (Osborn's _Essays on the Practice of Midwifery_.) It has been recommended to perforate the head at the sutures, on account of the greater facility in passing the instrument through them: but that part of the head which is lowest in the pelvis, or which, in other words, _presents_, must necessarily be the most convenient, not only for the introduction of an instrument, but also for the evacuation of the brain. When the perforation is made at a suture, the edges of the bones gradually overlap as the head diminishes in size, and thus close the opening, a circumstance which cannot occur when it is made through a bone. Splintering the bone in making a crucial opening has been objected to on the ground that the sharp edges and spiculæ are apt to wound the soft parts of the mother: of this, however, there will be but little danger so long as they are covered by the scalp, which we should be somewhat cautious of, and not tear or otherwise destroy the cranial integuments unnecessarily, for it has long since been remarked by the celebrated Peter Frank, that inflammation of the uterus produced by wounds from spiculæ of bone or sharp instruments becoming blunt, &c., usually prove fatal: it is also desirable to disfigure the head as little as possible. Still, however, we are far from recommending the trepan-shaped perforators which have been used by Professors Assalini, Joerg, &c. as they cannot make a sufficiently free opening, nor break down the skull to the necessary extent.