454 



POLAR PROBLEMS 



magnetic needle and the direction of flight; but in addition matters 

 are further compHcated by the fact that a Hne of equal magnetic dec- 

 hnation is not a straight Hne. Furthermore, the effects of magnetic 

 disturbances cannot be ignored or compensated for; and errors in the 



SUN AZIMUTH TABLES 



FOR USE IN LATITUDES ABOVE TO" 



INSTRUCTIONS FOR NORTHERN LATITUDES, 

 OBTAIN THE SUNS HOUR AI^GLE IN ARC FROM THF CHART, BEING CAREFUL TO MEASURE IT 

 CLOCKWISE FROM MERIPMN OF OBSERVATION TO THE SUWS MERIDIAN. THEN, WHEN THE 



SUN IS ^/^5f OF THE MfSlDMN OF OBSERU/fT/O/V, ^0ij T ^ r"^ PR6M THE HOUR ANGLE l80°/iND 

 THE pUflNT/r.Y EXTRACTED FROM THE- TABLES WITH LATITUDE, Dec LIGATION AND HOUR ANGLE AS 

 ARSUMENTS THE RESULT ;S TWe SUNS AZIMUTH MEASURED CLOCKWISE FROM THE POLE 



Fig. 4 — Example of tables prepared by the writer giving the quantity in arc to be applied to the 

 sun's hour angle to determine rapidly the sun's azimuth in polar latitudes. The tables have been 

 worked out for latitudes above 70° and for declinations of 0° to 23° from the celestial equator towards 

 the elevated pole. 



direction indicated by the magnetic compass and swinging motions in 

 the compass needle itself are caused by accelerations in speed, turns, 

 and curving courses. These errors increase as the magnetic pole is 

 approached and have their greatest effect when the navigator is flying 



