Perhaps the greatest improvements in the blades of modern times is seen in the forceps of Dr. Hopkins, above alluded to: the head curvature forms an elongated oval, admirably adapted to the form of the foetal head when considerably compressed during a difficult labour; and from the great breadth of the fenestræ, the pressure of the blades is applied over a large extent of surface; the pelvic curve is but slight, being greater on the posterior edge of fenestræ than on the anterior; the blades themselves are thin, their inner surface flat to ensure a firmer hold, their outer surface slightly rounded in order to be introduced with greater ease; and for a similar reason the edges of their extremities are somewhat thicker and carefully rounded in a peculiar manner. [Illustration: Naegelé's forceps.] The lock of the modern English forceps consists of two deep grooves, into which the shank of each blade mutually fits, so that the two blades are fixed upon each other merely by the pressure exerted upon the handles. In former times the blades were united together by a pivot, which could screw and unscrew at pleasure. This was abandoned by Chapman, who published the first work in English on operative midwifery.[82] He found that the forceps held better without the pivot than with it; and from what we have brought forward elsewhere (_Med. Gaz._ Jan. 8, 1831,) there can be little doubt that he invented the lock which is now generally used in this country. Chapman's forceps was adopted in France prior to this improvement in its lock, especially by Gregoire, and has retained the original pivot lock which now forms one of the most distinguishing marks between the French and English forceps. Although the pivot forms by far the firmest lock, for the blades can never slip from each other, still the difficulty in locking, and also in separating, the blades at a moment's notice, render it much inferior to the English lock. An ingenious modification was invented by the late Professor Von Siebold of Berlin, but the most perfect lock is that of Professor Brüninghausen of Würzburg, first introduced by ourselves into this country, and commonly known among the instrument-makers under the name of Professor Naegelé's forceps. The shank of one blade has a semicircular indentation, which at the moment of locking fits into a fixed pivot in the other: this, therefore, combines the advantages of the French and English locks. We can safely affirm, from extensive experience for many years, that there is even less difficulty in locking it than with the English lock: the blades are capable of instant separation, and yet when locked, the firmness of their union is equal to that of a pivot joint.