450 



POLAR PROBLEMS 



Gyroscopic Methods 



Theoretically the gyroscope could be employed in the polar regions 

 to determine position; but technical difficulties of construction and 

 adjustment are such that it is not likely to be developed while there 

 are simpler methods avail- 

 able, especially as it seems 

 probable that if ever the 

 short air routes across the 

 polar regions are utilized 

 commercially the radio 

 compass or wireless direc- 

 tion finder will succeed in 

 displacing all other methods 

 of navigation. 



Wireless Methods 



Direction and position 

 finding by wireless is being 

 rapidly developed. ^^ There 

 are two systems in use. 

 The first, and at present 

 the most efficient, is for the 

 aircraft to send out a signal 

 whose respective direction 

 from two or more ground 

 stations is determined by 

 them on receiving the sig- 

 nal. These direction lines 

 when plotted on a chart 

 should all intersect at a 

 point, which is naturall}^ 

 the position of the aircraft. 

 The ground stations then 

 signal this position to the 

 craft. Obviously it would 

 be more practical for the 



navigator in the aircraft to be able to determine the direction of sig- 

 nals sent out from ground stations and plot the craft's position himself. 

 This is the second method being developed. At present it is onl}^ 

 practical over short distances, for even under good conditions and over 



11 R. L. Smith-Rose: The Reliability of Radio-Direction Finding for Navigation Purposes, Year 

 Book of Wireless Telegraphy and Telephony, London, 1924, pp. 586-591; idem: The Progress of Radio 

 Direction-Finding During 1924 As an Aid to Navigation, ibid., 1925, pp. 543-547. For bibliography, 

 see Hydrogr. Rev., Vol. 3, 1926, pp. 200-205, Monaco. 



Fig. 2 — An example of position and direction finding 

 according to the position-line method described in the text. 

 In this figure the example is plotted, and in the adjoining 

 table it is worked out. 



