HANDBOOK OF MAGNETIC COMPASS 145 



Compensation, degaussing — Continued. 

 Procedure— 122-124, 107-110. 

 Checlv-off list— 107-110. 

 Precautions — 128. 

 Data, records — 126. 

 Residual devitaions — 126. 

 Components : 



Earth's magnetic field — 8, 9. 

 Ship's magnetic effects — 10-14. 

 Degaussing magnetic effect — 111, 112. 

 Deviation curve — 38. 

 (Constant A deviations or coefficient — 28, 38, 81, figure 19. 

 Correctors : 



Adjustment (magnetic) : 

 Types— 31, 32, figure 18. 

 Positioning— 32, 102, 92, 77. 

 Mechanics of — Figure 1, figure lb. 

 Effects— 91-102. 

 Interactions— 91-102. 

 Compensation (coils) : 



Types— 113-117, figures 39-43. 

 Limitations— 129, 131. 

 Effects— 131. 

 Mutual relationsliip— 109, 126, 127. 

 Corrector magnets — 31, 32, 81. 

 Current limitations in control box — 130. 



D 



D coefficient- 22-24, 38, 81, figure 19. 

 D sphere correctors. (/See Spheres.) 

 Deflection of compass by magnets— 123, 12ri 

 Degaussing compass compensating coils : 

 Installations— 113-117, figures 39-44. 

 Control boxes — 119. 

 Wiring— 118, 121. 

 Resistances of coils — 129. 

 Connection to degaussing — 121. 

 Electrical tests — 107. 

 Compensation. (See Compensation.) 

 Current and voltage limits — 129. 

 Effects— 131. 

 Operation— 126, 128. 

 Deperming — 106. 

 Deviation : 



Definition — 15, 45. 



Causes— 15-30, 111, 112, figure 19. 



Types of — Figure 19. 



Constant A. — (See A Coefficient.) 



Semicircular B and C. (See B and G Coefficients. > 



Quadrantal B and E. (See I) and B Coefficients.) 



Sextantal and octantal — 102. 



Oscillating. {See Heeling). 



