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tubing, 4 5/8 by 10 inches, which was heat sealed at both ends. 

 Two 5/8 inch cut steel washers were included to provide ballast 

 so that the card floated upright in the water with a minimum 

 of surface exposed to the direct effects of the wind. Assembly 

 of the cards was done by a commercial packaging concern. 

 Because experiments showed that the amount of air entrapped in 

 the plastic cover was variable and was often not sufficient 

 to allow the drift card to remain afloat, a soda-straw was 

 inserted at the time of assembly to insure that enough air was 

 present to float the card. 



During preliminary experimental design of the cards, as 

 well as on the first two cruises (September 8 and 29), a few 

 unweighted cards were used. These remained flat on the sur- 

 face of the water and were driven at considerable velocity 

 directly downwind „ At the time, neither the effects of the 

 wind on the immediate water surface nor on the possible 

 drift of surface films were being considered, and the use of 

 unweighted cards was abandoned. Now, however, considering 

 the difficulty of obtaining reliable wind data in this area 

 and because of the possible importance of knowing the drift 

 of '"grease balls" and other low density components of sewage, 

 we would recommend that if other surveys are undertaken in 

 the future, a certain percentage of unweighted cards be 

 released at all stations as a matter of routine. On the 

 cruises in Santa Monica Bay, too few of the unweighted cards 

 were released and later recovered to justify any conclusions 

 as to differential drift. 



