CHAPTEE XII 



Waves of Transmission of Oscillation Ripples. 



AET. 118. WAVES. 



WAVES may be divided into three main classes according as they are 



(a) Waves of Transmission. 



(b) Waves of Oscillation. 



(c) Ripples. 



In a Wave of Transmission, not only does the wave form advance, but 

 each particle of water over which the wave passes is translated forward 

 during its passage and is finally left at some distance ahead of its original 



FIG. 184A. 



position. Perfect waves of this type are solitary and the wave itself is 

 either wholly raised above or wholly depressed below the general surface 

 of the fluid. In the former case it is termed a positive ; in the latter 

 case a negative, wave. Such positive waves are formed by the sudden 

 opening of a sluice gate admitting a body of water into a long, level canal, 

 or may be formed in a long trough by the sudden immersion at one end, 

 of a solid body of volume equal to that of the required wave. The 

 negative wave of transmission is very unstable, and always gives rise to a 

 train of waves of oscillation. 



Method of Transmission. If the water when at rest be supposed sub- 

 divided by a series of equidistant vertical planes, perpendicular to the 

 direction of the wave's transmission, the columns which they enclose 

 suffer the distortion shown in Fig. 184A, during the passage of the wave 

 As the front of the wave approaches one of these columns the pressure on 



