k-Vh 



(Z,,T,) 



Sind 



h-^H 



(a) 



(b) 



FIGURES, (a) THE DISTANCE BETWEEN POINTS P] AND P2 ON A ZONAL 

 SECTION OF THE STYLUS TRACE WILL EXCEED THE DISTANCE, 

 d, BY THE FACTOR l/sine 9. (b) THE GRAPHICAL GRADIENT 

 ANGLE, e, IS RELATED TO MEASURES OF TEMPERATURE AND 

 DEPTH (SEE TEXT). 



