CERTAIN" MOVEMENTS IN MAN 



155 



graph, and measure the force expended from the data 

 afforded by the geometrical chronophotographs ; in 

 short, when the body mass is known, as well as the 

 position and movements of the centre of gravity, 



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Shovtdei 



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Fig. 105.— Geometrical chronophotograph of the movements executed in taking a high-jump. 



the force expended on the movement can also be 

 calculated. 



Mechanical Work done by Man in Walking. — In view 

 of the fact that it is possible to estimate the work 

 done in jumping by means of geometrical chrono- 



