264 



ANIMAL MECHANICS. 



Fig. 151. — Shoe for indicating when a 

 man's foot comes in contact with 

 the ground ; a transmitting tube 

 effects a communication between 

 the air-chamber and the chrono- 

 graphic tambour. — After Marey. 



Methods of Recording the Movements of Walking 



and Running. 



The Webers l studied the actions of walking and running, on a track 



of measured length. By means of 

 a watch they could determine the 

 period of any given pace ; for, know- 

 ing the space traversed, the time 

 taken to traverse it, and the number 

 of paces indicated by the foot-prints, 

 the mean duration and length of a 

 step could easily be calculated. 

 Further, they were able by this 

 means to determine the relationship 

 between the length of the step 

 and its duration, and arrived at 

 conclusions which will presently be 

 alluded to. 



By observation they established 



the fact that, in walking, the trunk 



and centre of gravity sink to a lower level than obtains in the erect 



position, and they found, moreover, that this sinking is greater the 



longer the stride. 



Chronographic methods- — M. Marey, 

 who lias rendered such signal service to the 

 physiologist by inventing useful methods for 

 recording the movements of the heart, the 

 blood vessels, and the muscles of the body, 

 has also been the pioneer in inventing chrono- 

 graphic methods for recording such move- 

 ments of the whole body as those of walking, 

 running, swimming, etc. 2 These methods do 

 not yield very full information, but they 

 give useful data as the exact times during 

 which the several limbs remain in contact 

 with the ground. 



The apparatus for recording the " paces " 

 of a man is as follows : — A pair of shoes 

 are constructed (Fig. 151), with thick india- 

 rubber soles, within each of Avhich is a hollow 

 cavity, communicating by a long tube with 

 a Marey's writing tambour. The two tam- 

 bours are arranged to record in vertical series 

 upon a revolving drum, which is carried in 

 the hand (Fig. 152). When a foot touches 

 the ground, a wave of pressure travels to 

 the corresponding writing - lever, which is 

 caused to trace an ascending curve upon the cylinder. 



The paces of the horse have naturally called forth much observation, and 



1 Wilhelm and Eduard Weber, " Mecbanik der menschlichen Gehwerkzeuge," Gottingen, 

 1836. Recently republished in vol. iv. of "Wilhelm Weber's "Gesammelte Werke." 



2 Ann. d. sc. not., Zoologie, Paris, 1872. His work recently epitomised in "Le muve- 

 ment, " English transl. by Pritchard, 1895. 



Fig. 152. — Pedestrian furnished 

 with special shoes and carry- 

 ing a chronographic appar- 

 atus. — After Marey. 



