APPENDIX A 



OUTLINE FOR COURSE OF STUDY 



I. General outline of magnetism. (See chap. II) : 



A. Magnetic lines of force. Magnetic poles. 



1. Opposite poles attract. Like poles repel. 



B. Magnetism : 



1. Permanent and subpermanent. 



(a) Changes due to deperming or vibration. 



2. Induced: 



(a) Varies with field intensity, alignment, and physical dimensions. . 



C. Earth's Magnetism: 



1. Earth's magnetic poles. 



(a) Red and blue, north and south, plus and minus. 



2. Earth's magnetic field. 



(c) "Variation in direction from true north. 



(6) Different vertical and horizontal components. 



(c) Charts of vertical intensity, horizontal intensity, angle of dip, 



variation. 

 id) Annual changes, anomalies, etc. 



D. Resultant field (vector problem) : 



1. Compass card — needle arrays. 



2. Compass deviation. 



E. Inverse square lavp. 



F. Shielding. 



II. Theory of magnetic compass adjustment. (See chap. Ill) : 



A. Permanent magnetic effects : 



1. Vertical component, H — oscillating effect vphen rolling. 



(a) Varies with latitude. 



2. Longitudinal component, B — semicircular deviation. 



(a) Varies with latitude. 



3. Athwartship component, C — semicircular deviation. 



(a) Varies with latitude. 



B. Correction for permanent magnetic effects — Use permanent magnet 



correctors : 



1. H effect — vertical heeling magnet. 



2. B effect — fore-and-aft B magnets. 



3. effect — athwartship C magnets. 



C. Induced magnetic effects : 



1. Vertical component at compass — heeling effect. 



(a) Varies with latitude. 



2. Vertical resultant — semicircular deviation. 



(a) Varies with latitude. 



3. Symmetrical distribution of horizontal soft iron, D — quadrantal devi- 



ation, maximum on intercardinal headings, 

 (a) Does not vary with latitude. 



4. Unsymmetrical distribution of horizontal soft iron, E — quadrantal 



deviation, maximum on cardinal headings, 

 (a) Does not vary with latitude. 



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