358 THE HUMAN MOTOR 



271. Marey's method of geometrical chronophotography was 

 as follows : The subjects of the experiments were clothed in 

 black garments on which white lines were drawn to represent 

 the spinal column, and the lines of shoulders, hips, and other 

 lines whose movements he desired to study. A series of straight 

 lines, representing the positions of the moving limbs as functions 

 of time, were then obtained on one plate, or film, with instan- 

 taneous exposures. Braune and Fischer also employed photo- 

 graphic methods in their experiments on the nature of bodily 

 movement, while their determinations of the centres of gravity, 

 the sizes, and weights of the various components of the human 

 body, were the result of experiments with corpses. Thus, having 

 ascertained the distribution of the masses of the body and the 

 laws of its movement, they were able to calculate the forces 

 exerted. 



It should be noted that in all such photographs the lower 

 members are never shown in complete extension ; hence the 

 vertical oscillation appears to be less than it really is. 



