390 POLAR PROBLEMS 



base at the edge of the ice barrier would be the best location for the 

 main base. 



Air Navigation in the Arctic^ 



Where navigation is to be done, it is very desirable for the plane 

 to have a closed-in cabin, accessible to the pilot's seat, so that the 

 navigator will have a chance to navigate out of the wind stream and 

 from time to time relieve the pilot. Air navigating in a cold wind 

 stream, or any wind stream, is a difficult matter. 



Aviation will have to make considerable advance before it will be 

 practicable to fly in the Arctic during the months of total darkness. 

 On the other hand, for long flights, the twenty-four-hour daylight of 

 the spring, summer, and autumn months is a great advantage, as there 

 is no dark zone through which to fly, as would be the case south of 

 the land of the midnight sun. A forced landing in darkness where 

 there are no lights is almost certain to end in disaster. It is also more 

 difficult to navigate at night, and under some conditions (such as a 

 cloudy night) impossible, at the present stage of development of air 

 navigation. 



USE OF THE magnetic COMPASS AND SUN COMPASS 



The navigation of aircraft in many of the Arctic areas presents 

 some difficulties that do not exist in areas generally frequented by 

 seacraft and aircraft. The compass needle not only may be sluggish, 

 but the variation of the compass may be unknown and very large 

 at the same time, amounting, in some areas near the line joining the 

 north and magnetic poles, to the maximum of variation of i8o°^. 



It is sometimes difficult in any locality to compensate the compass 

 of an aircraft. It should always be done under actual flying condi- 

 tions, because the angle of the airplane to the horizontal, the speed of 

 the motor, and the location of the equipment carried may affect the 

 compass needle. Five-gallon cans of gasoline, carried as extra fuel 

 for long flights, repair tools, etc., may exert a magnetic influence. 



In those Arctic regions where the horizontal directive force of the 

 earth's magnetism is comparatively small, this deviation, caused 

 by the magnetism of the plane, is naturally more troublesome and 

 sometimes very large. Some aviators exploring in the Arctic who had 

 planes with much metal about them have found it impossible to 

 compensate their compasses on the ground, no matter how closely 

 they strove to simulate flying conditions. Then, if on top of this the 

 navigator does not know his variation (a theoretical variation may 

 easily be in error as much as io°), he is very likely to get lost. 



2 On this topic see also Mr. O. M. Miller's paper below. — Edit. Note. 



3 See Figures i and 2 in Dr. Bauer's paper, above. — Edit. Note. 



