her prosthesis development, creating another one for an artificial hand, for which she also received a Prussian patent on 24 November 1836. This was the first usable self-powered upper limb prosthesis on record. Eichler then built a trade in Berlin by manufacturing prostheses. On 30 October 1837, Caroline Eichler married a man seven years her junior, the mechanic Friedrich Eduard Carl Krause from Bielefeld. She later divorced him but, even after the divorce, Krause repeatedly "extorted money from her." On the evening of 6 September 1843, Krause came to Eichler's Berlin apartment again, asking for money, when an argument ensued, during which, according to the criminal report, Krause murdered her with a pointed file. She died at age 34. Leg prosthesis The leg prosthesis developed by Eichler featured several advances over competing designs from that time. For example, her leg had a mobile, independently working knee joint, which was not previously available. Earlier designs either had no knee joint or, like the artificial legs described by the surgeon Ambroise Paré in the 16th century, had to be operated by pulling a cord. Eichler's construction consisted of a tinplate, brass (and later nickel silver sheet) shaft for the leg's stump, a hollow lower leg made of linden, willow or poplar wood glued over with canvas, and a foot with two parts, which were also made of wood, all attached to the jointed leg piece. The sheet metal for the femoral shaft could be cold-formed relatively easily, allowing the stump attachment to be adjustable. One of its important features was the weight of the prosthesis. It was much lighter in comparison to a solid wooden structure and weighed only about . Based on her experience as a nurse, Eichler gave great importance to the device's practical usability. Until then, it was common practice to fit prosthetic legs directly against the stump, which made long-term use impossible. In contrast, Eichler designed her prosthetic to fit on the stump after it was tightly wrapped with bandages and then a padded leather funnel. Then the prosthesis was pulled over the bandages and hung over the shoulder by a strap that was attached to the front and back of the funnel to avoid unnecessary pressure on the thigh stump. Her design allowed the knee joint to work without a locking device. It moved using a combination of gut strings and pressure-loaded coil springs, which, according to