Time-lapse photography of current effects is ac- 

 complished with this motion-picture camera. It is 

 mounted beneath a convex mirror which reflects the 

 sea surface to the horizon in a 360-degree arc. The 

 camera unit is raised to the top of the 40-foot mast 

 for operation. It takes photographs at 3- to 5-second 

 intervals. For viewing, these films are shown at 

 about lOOtimes normal speed. Beside drogue-tracking, 

 the pictures are also used to study the motion of 

 sea-surface slicks. 



Drogue movement measurements by 

 time-lapse photography show that the 

 horizontal current flow is strongest 

 near the surface (5 feet deep), in the 

 water column above the thermocline. 

 Speeds to 0.7 knot were recorded. 

 Other readings at 40 feet (below the 

 thermocline) were around 0.2 knot. The 

 360-degree surface photographs used 

 in this study also showed that the di- 

 rection of water flow was variable and 

 was mainly related to wind and tide. 



33 



