342 



[chap. 16 



HORIZON LEVEL WHEN 

 CENTER OF CIRCLE OF 

 BEST FIT COINCIDES 

 WITH ORIGIN 



270' 



270° 



BUCKLED HORIZON WITH 



TILT = X- CIRCLE OF BEST 



FIT TO BE BASED ON LEAST 



SQUARES (NOT EQUAL AREAS) 



180° 



Fig. 14. Dipmeter observations on several azimuths can be composed on polar diagrams 

 to reveal the altitude of the horizon circle with respect to the zenith. Three cases are 

 shown. 



Fig. 15. Horizon at a range of nautical miles under nearly calm conditions. Reticle 

 interval is 60 seconds of arc per division. 



