106 [Assembly 



tained in their relative positions by strong metalic plates attach- 

 ed vertically and immovably to the sides of the leg, through the 

 ends of which strong hollow bolts pass and are also immovable, 

 and upon which the thigh and leg pieces receive tlieir bearings 

 in their flexions and extensions, through the whole diameter of 

 the joints in solid wood substantially bushed. By this new and 

 substantial arrangement, no motion of the metalic parts where 

 they unite, is permitted; friction is reduced to the least possible 

 degree, oil is dispensed with, and all the lateral motions and 

 noise, peculiar to other kinds of joints, are prevented. 



The internal arrangements are strikingly in keeping with the 

 anatomical structure of the natural limb. Through the ingen- 

 ious application of springs, cams, eccentrics, and cords, the en- 

 tire limb is moved, controlled, flexed, and extended with the 

 most perfect ease and reliability. The movements very closely 

 resemble the natural limb. A lever and spring adjusted in the 

 lower part of the thigh and attached to the leg, serves to extend 

 and control the knee joint, thus answeiing the extensor muscle of 

 the natural leg ; while opposite and opposed to the extensor, a 

 strong cord is inserted behind the knee joint which suspends the 

 action of the leg when sufficiently extended, answering the action 

 of the semi-branaceous and crureus muscles or ham-strings of the 

 natural leg. This arrangement prevents that unpleasant concus- 

 sion peculiar to all tenon and mortice joints, as used in previous 

 constructions. 



A large and very strong heel curd, answering to the gastroo- 

 nemii muscles or tendo Achillis, extends from the heel up into 

 the calf of the leg, where it is connected with a cam playing 

 upon an eccentric, which in its turn is connected by a lesser cord 

 with the thigh, by which it is operated to extend the foot and 

 also enabling the \^earer to throw his whole weight upon the ball 

 of the foot, as upon the natural one, in walking, lifting, getting 

 into carriages, ascending flights of stairs ; and at the same time 

 affording a strong and life-like elasticity in walking. 



The foot and toe spring, and cord, which answer to the flexor 

 muscles of the ankle and toes, to elevate the one, and firmly com- 

 press the other to the 'ground, as experienced in walking, is a 

 compound arrangement, flexing the foot upon the ankle and ele- 



