224 



The National Geographic Magazine 



AIRSHIP VOYAGES BY ANALOGY 



In his studies of the fascinating prob- 

 lem of the best means to adopt for reach- 

 ing the North Pole in a dirigible, Mr 

 Wellman hit upon the idea of writing up 

 the log of his aeronef throughout a num- 

 ber of test voyages, assuming that the 

 winds throughout each voyage were the 

 same as those which prevailed at the 

 Pram. Accordingly, he named eight 

 dates, somewhat at random, but corre- 

 sponding generally to the date on which it 

 is expected his trip may be made from 

 Spitzbergen toward the Pole — the latter 

 part of July and early days of August. 

 These dates will be found on the next 

 page. The motor speed of the dirigible is 

 assumed at 12 miles (geographical) per 

 hour. The maximum retardation by the 

 dragging anchor in adverse winds is as- 

 sumed at 12 miles per hour. Allowance 

 is made for the effect of all winds oblique 

 to the course. For example, in voyage 

 B, from 10 p. m. to midnight, July 25, the 

 wind was S W. at 12 miles per hour, and 

 one-half of its movement, or 12 miles for 

 the two hours, is assumed as the "north- 

 ing" effect upon the airship. 



The start from Spitzbergen is made in 

 the first southerly wind that blows on or 

 after the first of the days named in each 

 of the periods, chosen arbitrarily. Thus 

 the log is written up hour by hour from 

 the Fram records, following the method 

 of navigation already described by Mr 

 Wellman in the foregoing pages. 



It will be remembered that Dr Nansen's 

 ship, the Fram, drifted for three years 

 through the Arctic Ocean, traversing in 

 part the very region the Wellman air- 

 ship is planned to sail across. As Mr 

 Wellman points out, no one can know 

 that the winds which his airship encoun- 

 ters on its actual voyage are to be like 

 those of any one of these 10-day Fram 

 records. But it is only reasonable to as- 

 sume that they will not be widely differ- 

 ent, probably not much better, probably 

 not much worse. 



In the most favorable of these exam- 



ples the vicinity of the Pole is reached in 

 28 hours. 



In the most unfavorable it is reached 

 in 152 hours, of which 68 hours are given 

 to work with the motors and 84 hours to 

 drifting with the retardateur. Inasmuch 

 as it is believed the aeronef can remain in 

 the air from 12 to 20 days, and the fuel 

 supply carried is equal to about 140 hours' 

 motoring, it will be seen that even in this 

 case of the most contrary winds only one- 

 half the radius of the airship is consumed 

 in attaining proximity to the Pole. 



It should also be borne in mind that an 

 essential feature of the expedition plan 

 is to carry a complete sledging equipment, 

 with motor-driven sledges, etc., and pro- 

 visions for 75 days, so that in case the air- 

 ship should fail through any cause, its 

 crew could resolve themselves into a 

 sledging party and continue their work 

 of exploration or make their way back to 

 the nearest land. 



The temperature is not an obstacle to 

 the success of the expedition, as it ranges, 

 during July and the first half of August, 

 about the freezing point, rarely going 

 more than a few degrees above or below 

 zero centigrade. The temperature in the 

 Arctic Ocean in summer is the most con- 

 stant to be found anywhere on the sur- 

 face of the globe, and this is a great ad- 

 vantage in aeronautic work, as the gas is 

 subjected to the minimum of dilatation 

 and contraction. 



In his studies Mr Wellman has taken 

 account of all other conditions, such as 

 the precipitation of snow, rain, or sleet, 

 which may weigh down the airship, and 

 he has made provisions to meet and over- 

 come this difficulty. 



Mr Wellman concludes with the pru- 

 dent observation that these analyses do 

 not show that he is certain of attaining 

 the Pole by airship, but that they do in- 

 dicate ground for a reasonable amount 

 of hope and demonstrate that the expe- 

 dition is planned on a practical and even 

 promising basis. 



