to the photographed curves. When the particle, because of mass 

 transport or specific gravity effects, did not traverse a closed curve, 

 the diameter was computed as shown on the curve, Figure 1 . 



It is assumed that the velocity due to mass transportation or 

 differences in specific gravity were uniform over the period during 

 which the orbit trace was obtained. Then the true diameter is the 

 mean of the distance between the tangents at points 3-1 and 3-5. 



DIRECTION OF WAVE TRAVEL 



STILL WATER LEVEL 



ORBITAL MOTION 



Figure 1. 



The same reasoning is followed for the determination of the vertical 

 diameters. 



The depth of the orbit center below still water level is considered 

 to be the depth of the mid point of the vertical diameter as determined 

 above. 



Mass transport. — The particle orbits were used to determine the 

 existence and magnitude of mass transport. Referring to the figure 

 of the preceding section, when a curve was open on the horizontal 

 diameter, the amount by which it failed to close was considered as 



