On page 364 we noticed the Artificial Leg of D. B. Marks, of this city, and since that time not a few enquiries have been made respecting it. The annexed engravings are views ot this artificial leg, they illustrate its Darts and its action in different positions. Figure 1 shows the limb and foot in section, ntwo of the positions of walking; figure 2 shows the same, bent as when the wearer is n a sitting posture ; figure 3 is a side view of-;he curved bar by which the movement of 'he knee joint is controlled, with a section of the lead of the rod and roller which are connect-;d with the foot; figure 4 is a front view of ;he same. Similar letters refer to like parts. This limb is intended to perform in walking all the movements of the natural one. In taking a step the foot is brought flat to the oround, with a perfect rigidity of the knee joint, which is maintained until the ankle is. bent by the throwing lorward of the body, as the opposite leg takes the succeeding step.— Phis bending of the ankle leaves the knee tree to make the slight bend that is necessaiy to raise the heel from the ground, and when the knee is thus bent, the ankle becomes stiff with the toe raised to prevent its dragging during the early portion of the movement of the leg in taking the next step, and remains stiff until it is necessary for the straightening of the knee, and the throwing down of the toe to bring the foot flat to the ground, both of which latter movements are effected simultaneously. The invention relates to .the means by which the movements of the knee and ankle joints are controlled, and the necessary rigidity is maintained during the cessation in those movements. A B and C, (f-ures 1 and 2) arejhethigh, TSg, milt looi, wKe!i"T ayTe"made of any known material of sufficient strength to support the weight of the body. The leg is cor-nected with the thigh and foot by hinge joints, a b, ball and socket joints, or any other connection most suitable to represent the kneesnd ankle joints, the thigh piece, A, and leg piece, B, being provided with stops, f f, which!' come in contact when the knee is straight, and thus prevent its knee being thrown too tar back.— The tbigh and leg may be made hollow.— the latter must have sufficient space within it for the passage ot a rod, D, which is connect-' ed at its lower end with the foot in front of the ankle joint, 6, which works through a guide or guides, c c, under one of which, or attached in some suitable way to the leg, B, a spring, d, coils round the rod, to whicb it is firmly secured. The effect sf this spring is to throw down the toe or front end of the foot. The upper end of the rod is furnished with a roller, e, which works in contact with the face of a curved bar, E, which is rigidly attached to the thigh at the back of the knee joint a. The curved bar proceeds from its place of attachment for some distance in a straight line, then forms a hollow curve, g, on its face, next a smaller rounded curve, A, then for a very short distance is nearly straight, and the terminating portion forms a small arc, i, which fits to the periphery of the roller at the top of the rod, D. In bending the knee the carved bar, E works under the roller, e, but when the leg is straightend as shown in figure 1, which represents the foot thrown forward and placed on the ground as when the step is made ; the terminating curve, i, of the curved bar fits to the back and under parts of the roller. The back of the roller coming in contact with the bar prevents the possibility of bending the knee without raising the roller, ", and rod, D, and holds the stops,/, in contact, making the km " perfectly stiff. The extremity of the bar, E holds up the roller, e, against the tension of the spring, d, and while it allows the front of the foot to bend upwards from the ankle with a moderate pressure, holds the ankle stiff when no pressure is used, and limits its downward movement; when the upper part Of the limb is moved forward, in taking the guc- ceeding step with the opposite foot. The limb is shown in figure 1, making this movement—the ankle is the fiist joint where any movement is made, and the bend which there takes place, moves the rod, D, and its roller. ", upwards from the position where they hold the knee stiff. As the heel is raised preparatory to lifting the whole toot, the ankle is still further bent, and the rod further raised, and there is a tendency to bend at the knee; this tendency is allowed to operate, and the roller, e, moves up the rounded curve, h, of the curved bar, until it reaches a position where it will rest, which will be about the position indicated by dotted circles in figure 1. By stopping in that position, the roller and rod keep the toe raised and the knee slightly bent during the early portion of the next step, but as the foot reaches the end of its forward movement the lower part of the limb, acquires such momentum that when the forward movement froip the thigh ceases, the knee is straightened by its continued motion, and the roller, e, descending the curve, A, throws down the toe and arrives at the hollow curve, i, where it again locks the knee stiff with the foot in position to be brought flat or nearly so upon the ground. To bend the knee for sitting down, the weight requires to be thrown upon the front of the foot, and the ankle bent enough to raise the roller, c, high enough to run over the rounded curve, A, when no further obstacle to the bending is encountered, until it is bent as far as necessary, when the back stops, j j, of the leg and thigh meet; the roller following the hollow curve, g, and thereby descending far enough to allow the foot to come down flat. No obstacle is offered to the straightening of the leg again, but that of the spring, d, during the early part of the movement, which will be easily overcome by placing the foot flat on the ground and raising the body. In the Crystal Palace the only two artificial legs on exhibition at present are Selpho's Anglesey Leg, and the famous one of Palmer, manufactured in Springfield, Mass. This latter leg was awarded a Council Medal at the World's Fair in ISSlj'and no less than fifteen bronze, sil/er, and gold medals have been awarded to it at various times, by different institutions. More information about the above illustrated leg may be obtained by letter addressedto D. B. Marks, care of A. A. Marks, 198 West 37th st., this city.