. A treatise on artificial limbs with rubber hands and feet ... No. 590. employed by some makers of placing one part of the joint by the sideof the other and bolting them together is unsatisfactory, as joints madethat way wear irregularly sidewise, and admit of a wabbling motionafter a short service. If the lateral strains on the upper sections couldalways be kept the same, this would not occur; but contracting thethigh of the artificial leg by lacing, in order to properly compress thereduced natural thigh, or by distending the artificial thigh in order toaccommodate a natural thigh that has g
. A treatise on artificial limbs with rubber hands and feet ... No. 590. employed by some makers of placing one part of the joint by the sideof the other and bolting them together is unsatisfactory, as joints madethat way wear irregularly sidewise, and admit of a wabbling motionafter a short service. If the lateral strains on the upper sections couldalways be kept the same, this would not occur; but contracting thethigh of the artificial leg by lacing, in order to properly compress thereduced natural thigh, or by distending the artificial thigh in order toaccommodate a natural thigh that has grown or enlarged, will forcethis irregular pressure, and unequal wrear on the bearings will cannot be avoided when the lap joint is used, but when one part 78 A. A. MARKS, ARTIFICIAL LIMBS, NEW YORK CITY. of the joint works within the slotted end of the other part, the entireupper section is held firmly to its bearings, and the wearing on thesides of the joints becomes minimized. The greatest wear in any joint is upon the bolt that holds the parts. No. 591. No. 592. No. 593. together, and as the wear is the greatest when a persons weight isdirectly over the leg and becomes less as the leg is flexed, the boltwears irregularly; and as the wearing surface on the bolt has hereto-fore been limited to the thickness of the section that works upon thebolt, the wear has been very rapid. A. A. MARKS, ARTIFICIAL LIMBS, NEW YORK CITY. 79 The object of the present improvement is to increase the wearingsurface as much as possible, and to have the wearing parts independentof the parts that resist strain, so that the wearing parts can be highlytempered and the parts that resist strain be left untempered, so thattheir supporting strength will not be impaired. In the improved joint, the wearing surface is increased over one hun-dred percent. It covers the entire surface of the bolt, and the interiorsurfaces of the holes in the lips of the lower joint. By referring to CutNo. 592 on op
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