SCIENCE IN SHORT CHAPTERS. 



heights, and by availing himself of these currents, he may reach the 

 Pole and return to his ship, or so near as to be able to reach it by 

 travelling over the ice in light sledges that will be carried for the pur- 

 pose. In making any estimate of the risk of Arctic aerostation, we 

 must banish from our minds the preconceptions induced by our 

 British experience of the uncertainties of the wind, and only con- 

 sider the atmospheric actualities of the Polar regions, so far as we 

 know them. 



Let us now consider the second danger, viz. that of being blown out 

 to sea and there remaining until the leakage of gas has destroyed tho 

 ascending power of the balloon, or till the stock of food is consumed. 

 A glance at a map of the world will show how much smaller is the 

 danger to the aeronaut who starts from the head of Baffin's Bay, than 

 that which was incurred by those who started from Vauxhall in the 

 Nassau balloon, or by Captain Boher, who started from Paris. Both 

 of these had the whole breadth of the Atlantic on the W. and S. W., 

 and the North Sea and Arctic Ocean N. and N. E. The Arctic bal- 

 loon, starting from Smith's Sound or thereabout, with a wind from 

 the south (and without such a wind the start would not, of course, 

 be made), would, if the wind continued in the same direction, 

 reach the Pole in a few hours ; in seven or eight hours at Eoher's 

 speed ; in fourteen or fifteen hours at the average rate made by the 

 Nassau balloon in a " moderate breeze. " Now look again at the map 

 and see what surrounds them. Simply the continents of Europe, 

 Asia, and America, by which the circumpolar area is nearly land- 

 locked, with only two outlets, that between Norway and Greenland 

 on one side, and the narrow channel of Behring's Straits on the 

 other. The wider of these is broken by Spitzbergen and Iceland, 

 both inhabited islands, where a balloon may descend and the aero- 

 nauts be hospitably received. Taking the 360 degrees of the zone be- 

 tween the 70th parallel of latitude and the Arctic circle, 320 are land- 

 locked and only 40 open to the sea ; therefore the chances of coming 

 upon land at any one part of this zone is as 320 to 40 ; but with a 

 choice of points for descent such as the aeronauts would have unless 

 the wind blew precisely down the axis of the opening, the chances 

 would be far greater. If the wind continued as at starting, they 

 would be blown to Finland ; a westerly deflection would land them 

 in Siberia, easterly in Norway ; a strong E. wind at the later stage of 

 the trip would blow them back to Greenland. 



In all the above I have supposed the aeronauts to be quite help- 

 less, merely drifting at random with that portion of the atmosphere 

 in which they happened to be immersed. This, however, need not 

 be the case. Within certain limits they have a choice of winds, 

 owing to the prevalence of upper and lower currents blowing in 

 different and even in opposite directions. Suppose, for example, 

 they find themselves N. of Spitzbergen, where " Parry's furthest " is 

 marked on some of our maps, and that the wind is from the N. E., 

 blowing them toward the Atlantic opening. They would then 

 ascend or descend in search of a due N. or N. by W. wind that would 

 blow them to Norway, or W. N. W. to Finland, or N, W. to Siberia, 

 or due E. back to Greenland, from whence they might rejoin their 

 ships. One or other of these would almost certainly be found. A 

 little may be done in steering a balloon, but so very little that small 

 reliance should be placed upon it. Only in a very light wind would 



