ARCTIC REGIONS AERIAL EXPLORATIONS. 179 



resultant would be a spiral course winding inwards in the 

 first case, and outwards in the second. The northward or 

 southward progress would be just the same as in a calm if 

 the wind were truly concentric to the Pole. Some rough 

 approximation to such currents may exist, and might be 

 dealt with on this principle. 



Let us now consider the third danger, that of the dark- 

 ness. The seriousness of this may be inferred from the 

 following description of the journey of the Nassau balloon, 

 published at the time : " It seemed to the aeronauts as if they 

 were cleaving their way through an interminable mass of 

 black marble in which they were imbedded, and which, 

 solid a few inches before them, seemed to soften as they 

 approached in order to admit, them still further within its 

 cold and dusky enclosure. In this way they proceeded 

 blindly, as it may well be called, until about 3. 30 A.M., when 

 in the midst of the impenetrable darkness and profound 

 stillness an unusual explosion issued from the machine 

 above, followed by a violent rustling of the silk, and all the 

 signs which might be supposed to accompany the bursting 

 of the balloon. The car was violently shaken. A second 

 and a third explosion followed in quick succession. The 

 danger seemed immediate, when suddenly the balloon 

 recovered her usual form and stillness. These alarming 

 symptoms seemed to have been produced by collapsing^ of 

 the balloon under the diminished temperature of the upper 

 regions after sunset, and the silk forming into folds under 

 the netting. Now, when the guide rope informed the voy- 

 agers that the balloon was too near the earth, ballast was 

 thrown out, and the balloon rising rapidly into a thinner 

 air experienced a diminution of pressure, and consequent 

 expansion of the gas. 



" The cold during the night ranged from a few degrees 

 below to the freezing point. As morning advanced the 

 rushing of waters was heard, and so little were the aeronauts 

 aware of the course which they had been pursuing during 

 the night, that they supposed themselves to have been 

 thrown back upon the shores of the German Ocean, or 

 about to enter the Baltic, whereas they were actually over 

 the Rhine, not far from Coblentz." 



