Eichler, were designed to correspond to human tendons and muscles. Her mechanism allowed the knee to bend while walking, and the springs brought the leg back to its extended starting position when it was lifted. The amputee did not have to help out by pulling a string. Eichler favorably compared the amputee's effort required to walk with her prosthesis to that of a toddler learning to walk or someone learning to dance. She said crutches were not necessary with her design as only a walking stick was required, and after a training period of one to two weeks, one would be able to walk on paved and unpaved floors and even climb stairs without using even a stick. Reception Experts from the Prussian Ministry of Medicinal Products and the Ministry of Trade and Industry subjected the prosthesis to an extensive examination before a ten-year patent was finally granted 23 November 1833. Eichler also received recommendations from numerous doctors, including those on the General Staff, Johann Wilhelm von Wiebel and Johann Friedrich Dieffenbach, who was the head of surgery at the Charité Hospital in Berlin. According to authors at the time, Eichler's prostheses represented a significant development in movement for amputees, especially when compared to other designs and, in German-speaking countries, it served for a long time as a model and standard for designs to follow. Hand prosthesis Eichler's artificial hand from 1836 is considered the first usable prosthesis of the upper extremity that could be moved without the assistance from the wearer's other, healthy hand. She built on progress made around 1812 by the Berlin dentist Peter Baliff for his design of a hand prosthesis. Baliff had adapted the "Iron Hand" of the feudal knight Götz von Berlichingen (also known as "Götz of the Iron Hand") and designed a new hand prosthesis, but it didn't get beyond the design phase. Its construction proved to be impractical and a prototype was never developed. One point of criticism for Baliff's hand, was that the fingers were designed to be actively opened but they relied on the force of springs to close, that is they passively closed, so the prosthesis lacked strength or could not adequately close. In addition, this prosthesis was made of heavy sheet iron and did not meet the wearers' practical anatomical or aesthetic needs. Eichler's hand prosthesis, like the Baliff's, was operated by the remaining muscles in the upper