152 



MOVEMENT 



of a tambour. Two recording tambours register two 

 curves on a revolving cylinder, one the curve of foot- 

 pressure, and the other that of the vertical discursions 

 of the head. 



Examination of these curves, enlarged, if necessary, 

 si lows that in all respects the laws of animal move- 

 ments conform to general laws— in this case to the laws 

 of ballistics. 



The areas of the curves which are described by the 



Fig. 102.— Superior curves; changes of height in the head during the jump. The 

 ordinate* DC and l)U' are proportional lo the height of the j imp. 



Inferior curves; pressure exercised by the feet on the ground. The shaded areas 

 show the quantity of mow. mad communicated to the body in the two jumps. 



dynanx (graphic needle express the exact equivalent of 

 the force employed in the effort of jumping. And it 

 is found that when two such areas differ, their ratio 

 to one another is as the square root of the height 

 jumped. If the area of the curves be the same, no 

 matter what be the shape, the heights of the jumps 

 must be the same. If two men of different weights 

 jump the same height, the areas of the dynamographic 



