160 MOVEMENT 



amount of the whole force expended, that is to say, 

 for the case in point, 2*5 kilogrammetres. 



C. Muscular Work done in moving each of the Lower 

 Limbs during the Period of Suspension. — The compli- 

 cated movements of the lower extremities correspond 

 to those of a pair of double-jointed pendulums in 

 unstable equilibrium : they are, however, not only acted 

 upon by gravity, but also by muscular contractions, 

 while the point of suspension itself moves with a 

 variable motion along a curvilinear trajectory. 



The method employed for measuring the energy 

 expended on these oscillations consists in measuring 

 the moment of inertia of the lower limbs in reference 

 to the axes of rotation, and by measuring on geo- 

 metrical diagrams the angular velocity which they 

 acquire. The result thus obtained is very small, 0*3 

 of a kilogrammetre for each step. Thus the most un- 

 certain determination in these measurements is prac- 

 tically a negligible quantity, and only very slightly 

 influences the total amount of energy expended on 

 each step.* 



According to the estimates indicated above, the total 

 amount of energy expended on a step is 9 kilogram- 

 metres. But even the most exact measurement of the 

 energy expended in any particular kind of pace is 

 much less interesting than the study of the actual 

 variations in the amount of work done as the pace 

 is accelerated. If we calculate the total energy 

 expended in fast running, the amount will be found 

 to be very different from that expended on slow 

 progression. The following are the estimates for 



* The practical importance of an exact determination of the energy 

 is very great; it is also most desirable that all the papers we possess 

 on this subject at the Physiological Station should be agnin studied 

 by the most approved methods. This subject is worthy of the con- 

 sideration of the greatesl mathematicians 



