arm stump using a pulling mechanism, but her mechanism differed significantly from his. The fingers were actively closed and stretched again by means of coil springs made of nickel silver wire, one in each finger joint. Gut strings with a diameter of about 1 mm were used for power transmission. Structurally, the fingers featured three movable joints and the thumb had two joints. Digits could also be moved individually using five separate sliders on the wrist, but only passively. In contrast to the iron hands of Renaissance times, the prosthesis had an opposable thumb that enabled a forceps grip with a sixth slider. Eichler's model also adopted design features from the Iron Hand: the wrist could bend at the wrist and a radial bearing made it possible to passively rotate the hand in relation to the forearm shaft (pronation or supination). The hand prosthesis was formed from nickel silver sheet modeled after two plaster casts (one from the stump of the arm and one from the healthy hand) and weighed only about . The phalanxes were covered with cork on the inside to improve the grip. The wearer of the prosthesis would have been able to write, sew and embroider with it, and also be able to lift loads of up to . The hand could easily be dismantled into its individual parts to simplify repairs and keep costs down, but the purchase price was quite high at 75 to 100 thalers. The nickel silver used by Eichler remained the standard material for hand prostheses into the 20th century. References 1843 deaths Patent holders 19th-century German inventors 19th-century women scientists women inventors People from Berlin People from the Kingdom of Prussia