sessed by the apparatus ; this involved an increase of rather delicate mechanism.
At one of the soirees given by the President of the Royal Society in 1845, the boy for whom Sir George Cayley made the artificial hand was introduced, and Prince Albert " shook " him by his mechanical appendage. The hand had only one finger worked by the mechanism ; but there were the proper number of cork fingers united side by side, and fixed to one broad thin steel plate, jointed, and covered with continuous leather, stitched down to mark the distinction of the fingers under it. But where a more expensive apparatus can be afforded, and the appearance of having a real hand is sought for, the thin steel plate can be separated into digits, though united at the base as in a common hand, and jointed at the proper places in due proportion to each finger.
In another form of artificial band, made by Sir G. Cayley, in 1847, there is a case or sheath, into which the stump of the arm is introduced. A spiral spring is fixed at one end to this sheath, and at the other to a bent lever ; while the middle of the lever is con nected with the mechanism of rods which move the artificial thumb and fingers. In this arrangement, the wearer uses his sound hand to work his artificial hand. He presses a little button which is connected with the bent lever ; by pressing this towards the wrist, the fingers and thumb open to receive any object they may be intended to grasp ; and when this pressure from the other hand is taken off, the grasp takes effect, without further effort, till released by a contrary move ment. The mechanism is very simple, and
is attached wholly to the lower arm, near the stump. But as the sound hand must be taken from anything else it has to perform, at the time the artificial hand is thus put to work ; and as it may on other accounts be inconve nient to work the apparatus in this way, Sir George invented a very ingenious means of working the hand by the movement of the upper arm or shoulder-joint.
M. Magendie described to the Paris Aca demy of Sciences, in 1845, an artificial arm, invented by M. Van Petersen. A sort of stays are fixed round the breast of the person ; and from these arc brought cords made of catgut, which act upon the articulations, according to the motion given to the natural stump. The apparatus was found to be very effective. It was tried (among other patients) on an invalid soldier, who had lost both arms in the wars of the empire, retaining only tbe stumps. With the aid of two of the artificial arms, he was able to perform many of the functions which had hitherto been performed for him. M. Magendie considers this contrivance to be the best substitute for a natural arm yet introduced.