are shown in table 1. For the visibility readings, the disc 

 was held in a vertical position and observed by a submerged 

 diver. 



TABLE 1. RELATION OF HORIZONTAL 

 TRANSPARENCY AND VISIBILITY. 



Visibility 

 (with Secchi disc, in feet) 



Transparency (per cent) 

 (with hydrophotometer) 



2 



33 



5 



44 



10 



61 



15 



73 



20 



82 



25 



87 



30 



90 



35 



92 



40 



93 



45 



94 



50 



96 



To obtain temperature, a plastic -sealed thermistor was 

 mounted on the cart at the same level as the hydrophotometer 

 (fig. 3-C). The readout for this thermistor was located on 

 a panel (fig. 5, lower right) near the X-Y recorder. Temper- 

 atures were read to the nearest tenth of a degree Fahrenheit. 



A depth indicator (fig. 5, left), on the same panel, 

 provided a quick visual check of the cart location. The sensing 

 element for this indicator was contained in a junction box on 

 the cart. 



The wind speed and direction were continuously recorded 

 on the tower. The instrument used for this purpose was an 

 ML-400C/UMQ-5 anemometer manufactured by Rett Products 

 Co. 



In order to relate turbidity to organic material in the 

 water, a sampling system was required. A submersible 

 pump (fig. 3-D) mounted on the cart met this requirement. 

 The intake to the pump was between two flat, horizontal 

 discs about 30 centimeters in diameter and about 1 centimeter 



10 



