148 HANDBOOK OF MAGNETIC COMPASS 



Magnetic : 



Poles — 5. 



Lines of force (flux) — 5. 



Retentivity — 6. 



Attraction — 5. 



Repulsion — 5. 



Earth's field: 



H and Z—S, 14. 

 Variation — 9. 

 Dip— 8. 

 Magnetic latitude — 8. 



Meridian — 9. 



North— 43. 



Heading — 43. 



Azimuth — 57, 59. 



Adjustment. (/See adjustment. ) 



Correctors — 31, 32. 



Circle— 104. 

 Magnetism : 



Definition — 5. 



Permanent — 6. I 



Induced — 6. 



Subpermanent — 12. 



Red and blue, + and — , etc. — 7. 



Terrestrial — 7. 



Ship's— 10, 11. 

 « Residual — 74. 

 Meridian angle — 61. 



N 

 Napier's diagram : 



Used for— 47, 42. 



Example — figure 42. 

 NE./SW. coils— 116. 

 NW./SE. coils— 116. 



O 



Operation of compass : 



Sluggish— 33. 



Unsteady— 33. ^ 



Reliability— 37, 106, 110, 103, 90. 



Frozen — 35. 

 Oscillating deviations. (See heeling.) 



Pelorus : 



Use of— 51, 52, 54, 55, 56. 



Alignment — 75. 

 Permanent magnetism : 



Definition of — 6. 



Varies with — 6, 13. 



Bftects on compass — 16, 17. 



Correction for— 31, 32, 35, 81. 



