Page the 10th of his preface, he has the candor to own, that he does not absolutely pretend that success will always attend its application, even in the cases he points out.
Page the 36th, and seq. of his observations, after having exploded the forceps, and other instruments of the authors who have preceded him; and after having described the alterations and corrections made in the English and French tire-têtes, he gives us indeed the better opinion of his, by a fair confession of the insufficiency of them all without exception, and even of his own: by which, however, it is plain, he can mean no more than that, imperfect as they are, they all are still preferable to the hands alone; but the question of this superiority is as constantly as it is shamelessly begged by him, and all his fraternity of instrumentarians.
Thus however he expresses himself as to his own instruments. “This instrument is actually, to all appearance, now at the very utmost degree of perfection, to which it is possible for it to arrive, without however having all the perfection that might be wished, for the most expert practitioners in the use of it, agree in the opinion.
“First, of the difficulty of its introduction in certain cases.
“Secondly, of its stubbornness as to the crossing of the blades.
“Thirdly, of its contributing to tear the fourchette, or frænum labiorum.”
[Our author is very angry, that Boëhmer, who, in his critical objections, opposes those his own words to him, has not added the subsequent lines.]
“The correction I have made in this instrument (continues Levret) by means of the shifting axis, has rendered the difficulty of crossing the blades less considerable, and the two following reflexions may serve greatly to overcome the other two inconveniences.”
But should it be granted to Levret, that the shifting axis somewhat lessens the difficulty of crossing the blades of this instrument, it would still remain too great an one, for all that correction. The reflexions he adds, for the overcoming the other two inconveniences, carry no conviction with them; and indeed he himself seems to think so, by his adding afterwards (p. 99.)
“To obviate this inconvenience of tearing the fourchette, or the perinæum, I caused to be made a curve forceps, as to any thing else not differing, in its dimensions, from the first. I took the idea of it from the curve pinchers used in the operations of lithotomy. It will be easier to conceive, than for me to describe the advantage it must gain by it. That was not however the only end I proposed by it, as all the good practitioners at present agree on the small efficacy of the common forceps, in the case of a head stuck in the passage when the face is turned upwards.”