64. It is evident that the bandage or roller (g g) so unites the pelvis to the external splint (AA), that the latter cannot be pushed upwards, without drawing the former in the same direction, as well as the superior fragment which adheres to it. But if, after this roller is fixed, the lower one (L) be tightened, the first effect produced is, to push the external splint forcibly upwards; the second, to draw the leg, and with it the inferior fragment downwards; so that, by fixing the roller (L) in the notch and mortise of the splint with the necessary degree of tightness, extension and counter-extension are made permanent. By this means the muscles, being kept on a stretch, lose by degrees their power of contraction, which is still further diminished, by the immoveable state in which they are kept, and by the compression made on them by the bandage of strips. So that, on the one hand, the inferior fragment will have no tendency to rise upwards, and even if it had, it will meet with a sufficient resistance to prevent it; while, on the other hand, the superior fragment will not be pushed downwards by the pelvis. 65. To this advantage is added that of a state of perfect immobility. The pelvis, the leg, the thigh, and the foot being firmly fixed on the external splint, constitute one entire whole, all the parts of which must retain, with respect to each other, the same relative position. Should even a stroke be accidentally given to this assemblage of parts now converted into a solid whole, each portion of it will move at the same time, there will be no partial motion, and the relative position of the parts will not be changed. Hence the advantage of being able to raise the patient without apprehension; a most desirable circumstance indeed, in a position so painful and so long continued (26). The external splint, being extended beyond the sole of the foot, prevents the lower fragment from obeying a tendency, which it sometimes has, to displace itself by a rotation on its axis. Should this tendency be towards the internal side, an occurrence much more rare, the lengthening of the internal splint will effectually prevent it.