THEORY OF ADJUSTMENT 



21 



horizontal soft iron. In addition to this magnetic A enor, there 

 are constant A deviations resulting from (1) physical misalignments 



North heading by Northeast heading East heading by Soutlicjisf ht-adin^' 

 compass. by compass. compass. by comiiass. 



E.Dev 



Compass 



V/.Dev. 



Compass Needle 



No deviation. 



Maximum devia- 

 tion easterly. 



No deviation. 



"D" Deviations 



Maximum devia- 

 tion westerly. 



Compass Heading - Degrees 

 FiooRB 1.5. — Effects of symmetrical horizontal D induced magnetism. 



\ I 



FiGURK 16. — Unsymmetrical arrangements of horizontal soft iron. 



of the compass, peloriis, or gyro, or (2) errors in calculating the sun's 

 azimuth, observing time, or taking bearings. 



