distribution of energy in the v;aves after each of the first five 

 strokes. As shown in the last line of the table a definite 

 pattern has already developed after five stroke?; the v;aves v.^hich 

 have traveled the greatest distance have very little energy, the 

 wave which has traveled half way has an energy E/2 , and each of 

 the '#aves closest to the laachine has an energy which approaches 

 the full amount E. When a large number of strokes have been 

 completed these gradations are much clearer and the distribution 

 of energy can be represented schematically by the curve in Figure 

 10, which shows that the energy advances with a definite "front." 

 At the front the wave height increases from nearly zero to nearly 

 its full value in a distance corresponding to a small number of 

 -/vave lengths, and this front advances with half the wave velocity . 



Table II 

 Advance of Waves from a Wave Machine into Still Water 



I'vumber of Relative energy of advancing waves 

 strokes 



1 1/2 



2 3A 1/4 



3 7/8 4/8 1/8 



4 15/16 11/16 5/16 1/16 



5 ■ 31/32 26/32 16/32 6/32 1/32 



When applying the above reasoning to the behavior of wind 

 waves which advance into regions of calm it is necessary to con- 

 sider also the following facts: (1) the wave loses energy because 



28 



