MOTION. 



467 



TABLE 10. 



In the following table we. find the proportion 

 between the duration ot the step and the 

 time of the leg resting itnd 

 during very diversified paces. 



These experiments prove that the time in 

 which the leg is swinging is least in the quickest 

 pace, and is equal to half the whole time of 

 oscillation of the leg ; that it increases in pro- 

 portion as the step becomes slower; that, con- 

 sequently, that division of lime which the 

 swinging leg occupies in describing its entire 

 curve is increased by one-half of the entire 

 portion of time, and more in proportion as the 

 pace becomes slower. This gives rise to an- 

 other range of experiments which have been 

 made by the Messrs. Weber with the same 

 design, of which the following table is the 

 result.* 



TABLE 11. 



Experiments on the time in which the leg 

 stands on the ground, with various degrees 

 of velocity in walking. 



Whence we deduce the following comparison 

 between the duration of the leg standing and 

 that of its swinging. 



The number of steps which a person can take 

 in a given time in walking depends, first, on 

 the length of the leg, which, governed by the 

 laws of the pendulum, swings from behind 



* In these experiments the footsteps were t.iken 

 on the ball only. 



forwards : secondly, on the earlier or later in- 

 terruption which the leg experiences in its arc 

 of oscillation by being placed on the ground. 

 When the hinder leg has quitted the ground, it 

 swings forward by its own gravity, in conse- 

 quence of its freedom of motion in the ilio- 

 femoral articulation and its oblique position ; 

 and, in order that the body may be supported, 

 it must, at least, move so far forwards that the 

 foot may arrive at a position vertically under 

 the head of the femur ; for in that direction 

 the leg not only supports the body with least 

 effort, but it is also in that position that it can 

 most easily avoid any impediment in its path 

 by transferring the point of support to any por- 

 tion of the sole of the foot, particularly if the 

 latter be turned outwards, which gives a greater 

 security than when it is directed parallel to the 

 line of motion. The weight of the swinging 

 leg and the velocity of the trunk serve to give the 

 impulse by which the foot attains a position 

 vertical to the head of the thigh bone ; but as 

 the latter, according to the laws of the pendu- 

 lum, requires, in the quickest walking, a given 

 time to attain that position, or half its entire 

 curve of oscillation, it follows that every person 

 has a certain measure for his steps, and a cer- 

 tain number of steps in a given time which in 

 his natural gait in walking he cannot exceed. 

 We can easily ascertain the time it requires to 

 accomplish the quickest step in walking, which 

 is equal to the half vibration of the leg made 

 with relaxed muscles. In order to make the 

 steps follow each other in much slower succes- 

 sion, the foot is not placed on the ground when 

 it arrives in the perpendicular position, or the 

 half oscillation from behind forwards as in the 

 rapid pace, but we plant it on the ground 

 somewhat later when the foot has described 

 more than half the curve of vibration. From 

 these principles we conclude that the man in 

 fig. 255 walks much faster than that in fig. 256; 

 in fact the former makes steps 27.559 in. in 

 length, whereas in the latter the steps are barely 

 23.622 in. in length; and whereas the first 

 makes a step in 0".35, the second takes 0".422 

 for a step, so that the velocity of fig. 255 is 

 nearly double that of jig. 256. These figures 

 are represented as walking on the toes, as if the 

 foot always touched the ground in the same 

 position, and their steps are shorter than when 

 the entire sole is brought into action. Fig. 255 

 shows the greatest step which it is possible to 

 make with the toes. The steps are shortest in 

 fig. 257, in which the difference of the heights 

 of the centre of gravity, compared with that of 

 fig. 255, may be easily seen.* 



In figs. 258, 259, and 260, the legs are of 



* These figures, with the others upon the same 

 plan, reduced to jgth the natural size, are drawn 

 in accordance with the principles on which the 

 theories of walking, running, and leaping are 

 based. They are taken in the various instants of 

 a step as seen through a revolving disc, con- 

 structed upon the principles of the stroboscope in- 

 vented by Dr. Faraday, and modified so as to 

 apply to these purposes by Stampher.t These 



t Vide Poggendorft's Ann. vol. 22. p. 600. 



2 H 2 



