mention.r^d periodic motion, thei^e are known bo exist in the 

 oceans internal waves of periods of the order of magnitude of 

 a few minutes. 'Ihe most complete treatment of these short 

 period internal waves has been given by Ufford (191^-7 a, b, c). 

 These papers derive relationships rrivin- the amplitude, period, 

 and wave length of these waves for several special cases of 

 multilayered systems. Ufford 's work seems to give promise of 

 being of practical value in the study of these waves, although 

 as yet the present project has not been extended beyond consider- 

 ation of the semidiurnal and diurnal periods » Data have been 

 collected, however, which Illustrate this effect, and examples 

 are given in figures 22 and 23. It will be noted in figure 22 

 that superimposed on what is possibly the major semidiurnal 

 tidal variation are many small oscillations of a period of a 

 few minutes. 



HOUR 

 2100 



100 



: no 

 ; 120 



130 

 140 

 150 

 160 

 170 



FIGURE 22 SHORT PERIOD FLUCTUATIONS OF THE THERMOGLINE AT 

 WEATHER SHIP BRAVO, 56°N.,5I°W, 2000-2200Z, 13 

 SEPTEMBER 1945. 



46 



