ATTITUDES ON THE KNEES, ETC. 441 



as to fix the shoe, as far as possible, and render the attitude more sta- 

 ble. The use of shoes interferes largely with the exercise of the toes, 

 which, in the savage, are capable of diversified and considerable action. 



The use of the fibula is, to serve the purpose of a clasp, as its name 

 imports. The tibia exerts its pressure chiefly towards the inner part 

 of the foot, and, consequently, were it not for the fibula, which passes 

 down below the articulation, dislocation outwards would be constantly 

 menacing us. The fibula has no participation in the transmission of 

 the weight to the ground. 



The conditions for equilibrium, as applicable to man, have been 

 already indicated. If the base of susteritation be rendered extensive in 

 any one direction, as by widely separating the feet, the attitude is more 

 firm in one direction, but less so in the other. It is as firm as possible 

 in every direction, when the feet are turned forwards parallel to each 

 other, and are separated by a space equal to the length of one. What- 

 ever diminishes the base of sustentation, diminishes, in like proportion, 

 the stability of the erect attitude. Hence the difficulty of walking on 

 stilts or wooden legs, on the toes, tight rope, &c. It seems that the 

 inhabitants of Les Landes, 1 in the south-west of France, are enabled 

 by habit to use stilts with singular facility. The sandy plains, that bear 

 this name, afford tolerable pasturage for sheep; but, during one part of 

 the year, they are half covered with water ; and during the remainder, 

 they are very unfit walking ground, on account of the deep, loose sand, 

 and thick furze. The natives, in consequence, habituate themselves to 

 the use of stilts or wooden poles, the former of which are put on and off 

 as regularly as parts of their dress. With these they walk readily over 

 the loose sand or through the water, with steps eight or ten feet long. 

 The difficulty, in this kind of progression, does not arise solely from the 

 smallness of the base of sustentation, but from the greater height to 

 which the centre of gravity is thrown, which renders the equilibrium 

 unstable. 



Standing on one foot is necessarily more fatiguing, as it requires the 

 strong and sustained contraction of the muscles that surround the hip- 

 joint, to keep the pelvis in equilibrium on the os femoris; especially as 

 the body has a strong tendency to fall to the side that is unsupported. 

 The muscles, that prevent the trunk from falling in this direction, are 

 the glutsei, gemelli, tensor vaginae femoris, pyramidalis, obturators, and 

 quadratus femoris. The use of the neck of the thigh-bone and the 

 great trochanter is here manifest. The base of sustentation, in this 

 case, is the space occupied by the foot which is in contact with the soil; 

 and it need hardly be said, that if this be still farther diminished, by 

 attempting to stand on the toes, the attitude cannot be sustained. 



In the attitude on the knees, the centre of gravity is brought lower, - 

 but the base of sustentation is smaller than on the feet. The patella 

 has to bear the chief pressure; and as it is not provided with a fatty 

 cushion such as exists at the sole of the foot, the position becomes pain- 

 ful, and the surface soon abraded. These remarks apply to the case, 

 in which the knees only come in contact with the soil. When the feet 



1 Arnott, Elements of Physics, 3d Amer. edit., i. 15, Philad., 1835. 



