He further describes an artificial forearm, which can, by the aid of the sound hand, be brought into any degree of flexion and maintained there by the use of a pawl caught into meshes of a cog wheel. The artificial arms described by Ambrose Parè, although extremely heavy, seem to have been in favor until the latter part of the eighteenth century; at this time a monk of the order of Carmelites designed a hand made of sheet tin, with movable fingers and thumb, to be articulated by movement of the stump, but we are informed that it was too complicated to be used with any degree of success except in cases of amputation near the wrist joint. We have a description of an arm made subsequently of leather and covered with sheepskin, colored in such a manner as to represent the appearance of the human skin, and to make it appear more natural the nails were made of white horn. The improvements in the hand were mostly in the appearance, without any important addition to its utility or usefulness.
In 1818 a Dr. Graefe suggested the construction of an arm susceptible of manipulation by means of cords attached to a corset surrounding the shoulders, the arm to be moved without the aid of the sound hand. This principle of attachment for the movement of the forearm and fingers is followed to the present time with various modifications.
The early history of artificial arms seems to refer mainly to their special construction and application for people of renown who had suffered the loss of their natural extremities. Until a comparatively recent period the impracticability, on account of complicated heavy mechanism, and the great expense of these appliances, precluded anything like a general demand for their use. As the inventive
59
