442 



TYIiER AND PREISENDORFER 



[chap. 8 



(a) 



(b) 



Fig. 23. Photocell-type instrument designed by R. W. Austui (unpublished) for the 

 determination of K and R. This instrument is equipped with a diffusing plastic 

 sphere which replaces the upper irradiance plate thus making it possible to determine 

 the distribution functions {D,±) and the absorption coefficient, a. A pressure 

 transducer, visible in Fig. 23a, gives accurate depth determination. A "deck" cell 

 shown in Fig. 23b monitors the surface lighting. 



