13. Hence it follows, that by tying on each side, one end of the upper roller to the corresponding end of the lower one with sufficient tightness, the two indications above laid down (12) are accurately fulfilled. 14. But, in general, the common bandage is sufficient, as I have already mentioned, even in cases of oblique fractures, to prevent the ascent of the lower fragments on the upper ones. Desault never employed any others in the last years of his practice, and it was only in cases of extraordinary disposition to muscular contraction, that he ever had recourse to the second kind. By means of the common apparatus, he was able to prevent the overlapping of the fragments from forming any protuberance on the anterior and internal part of the leg. 15. We must acknowledge, however, that this apparatus is liable to the same objection with most others intended for permanent extension. The roller placed below the knee, for the purpose of counter-extension, surrounds almost all the muscles, which tend to make the inferior fragments overlap the superior ones, by drawing the foot upwards. By pressing on and irritating these, it favours, and even excites their contractions, and, by that means, gives rise to a shortening of the limb, the very accident which the apparatus is intended to prevent. This inconvenience induced Desault, in a particular case, to substitute to the preceding apparatus, that used for permanent extension in fractures of the thigh. MEMOIR XV. ON THE DIVISION OF THE TENDO ACHILLIS. 1. It might be supposed that a work on diseases of the soft parts, would be a more proper place for this article, than the present one, where my express object is to treat of affections of the hard parts. What induces me to insert it here is, the analogy which exists between a division of the tendo Achillis and a fracture of the os calcis, the light which the treatment of the one throws on that of the other, and the example of the celebrated Petit, who, in his work on diseases of the bones, speaks also of this division. § I. OF THE CAUSES AND VARIETIES. 2. The division of the tendo Achillis is the result, either, 1st, of the action of a cutting instrument; or, 2dly, of muscular action: hence two very different modes of its production, the one by a wound, the other by a rupture. The first is not a very rare accident, because the projection of the tendon exposes it oftentimes to the stroke of external bodies: the second, though but little noticed by the ancients, has been frequently observed by the moderns, since their attention was called to it by Petit.