HUMAN MOVEMENTS 127 



threw some light upon the mechanism of animal 

 locomotion.* 



This learned Neapolitan professor applied to the 

 case of moving creatures the same mechanical laws 

 which had recently been discovered by Galileo, and 

 showed that the effect of muscular force made itself 

 felt partly on the mass of the body, and partly on 

 another mass which was called the point of resistance, 

 and he reduced to its simplest form the general theory 

 of locomotion. But, to impart some accuracy to the 

 study of human movements, it was found essential to 

 construct instruments to measure the range, velocity, 

 and sequence of the various phases of movement, not 

 only in walking, but also in running, jumping, etc. 

 The force exercised in executing these different move- 

 ments should also have been measured; but the 

 necessary instruments were not in existence. 



Two celebrated mathematicians, the brothers Weber, 

 realized the necessity for accurate measurements, but 

 inefficient instruments were all they had at their 

 disposal. A level piece of ground of known length, a 

 watch provided with a second's hand, and a performer 

 was all they had to work with ; they could therefore 

 only obtain a small number of measurements with 

 regard to the relationship between the frequency and 

 length of stride, of the extent of the vertical head 

 displacements and of the various inclinations of the 

 body, and even then these measurements had to be 

 corrected. 



AVith the assistance of the graphic method, we deter- 

 mined to introduce accuracy into these studies, but it 

 was chiefly by means of chronophotography that we 

 arrived at a scientific interpretation of the various 

 bodily movements. 



Before giving the results furnished by this method, 



* Borelli, De Motu Animalium. 



