May 10, 1883] 



NATURE 



39 



The winds, therefore, which should produce snow in 

 the interior, must, if coming from the Atlantic, have in 

 the first instance, crossed the broad ice-belt generally 

 encircling the east coast of Greenland, and then the 

 mountains on the coast, some of which we know are very 

 high, and, if coming from Davis Sound, the mountain 

 ridge itself. In both cases the wind would assume the 

 character of the " Fohn " wind, i.e., it must, after passing 

 the mountain-chains on the coasts, be dry and compara- 

 tively warm. The law of the " Fohn " is, as is generally 

 known, dependent on the circumstances explained below. 



If ACS indicates a mountain, and a wind so dry that 

 no deposit of moisture takes place on the top passes from 

 AC to B, the air will certainly be chilled in passing C, in 

 consequence of the lower barometric pressure and con- 

 sequent expansion of the air ; but the same cause which 

 produces the lowering of temperature when the wind 

 ascends has also the effect of liberating its heat, and the 

 air will become warmer as it descends from C to B. The 

 compression and rise of temperature are in the latter 

 case precisely analogous to the expansion and fall of 

 temperature in the former, and the dry air, in passing 



the mountain, has, therefore, on reaching B, not suffered 

 any change whatever in temperature or quantity of 

 moisture. Quite different will, however, be the result 

 if the air ascending at A is saturated with moisture, as, 

 for instance, air passing a great expanse of water. In 

 that case the air will expand and become colder, just as 

 it ascends from the water surface to the mountain top, 

 but, at the same time, part of the moisture will be con- 

 densed on the top, whereby the latent heat of the 

 hydrogen will be set free and a rise of temperature 

 take place, and this will, to a certain extent, minimise 

 the fall of temperature caused by the expansion of the 

 air. The air will retain the heat thus set free, even after 

 it has reached, in a dry state, the point B, and the air, 

 originally moist, has, when it has passed the mountain, 

 attained a higher degree of heat, but less moisture than 

 at the moment of ascending. It is in fact dry and 

 warm. 



These causes are not only the reason of the dry warm 

 "*' Fohn " winds in Switzerland, and the very remarkable 

 circumstance that it is under winds from the snow- 

 covered mountains that the snow disappears in Swedish 

 Lappland, but they play also an important part in the 

 climatic conditions of the whole globe. They are, for 

 example, the cause of the difference in climate and flora 

 of the two sides of the Andes, of the east and west coasts 

 of Tierra del Fuega, and the eastern and western parts of 

 Australia. They are the chief cause of the deserts which 

 cover the interiors of Asia, Australia, the northern portion 

 of Africa,and certain partsof America, while in Sweden they 

 produce the constant western winds, and the consequent 

 prolonged drought which invariably occurs in spring time 

 in the central part of the country. The same laws of 

 the temperature and moisture of the air must also pre- 

 vail in Greenland. Here too the ocean winds must be 

 moist, and this moisture is usually deposited in the form 

 of snow on the mountains along the coast, whereas all 

 those reaching the interior, whether from east, west, 

 north, or south, must — if the orographical construction 

 of the country is not entirely different from that of others 

 on the globe — be dry and comparatively warm. And in 

 consequence of this circumstance, the snow-falls in the 

 interior of Greenland cannot be sufficient for maintaining 

 a " perpetual " inland ice. 



It cannot, however, be asserted that the country should 

 here form a deserted, treeless tundra ; one encounters 

 in Siberia forests with giant trees under climatic conditions 

 far more severe than those we may assume are to be 

 found in the interior of Greenland. That the country 

 should prove true to its name has besides been asserted 

 by the celebrated botanist Hooker, from his studies of the 

 flora of Greenland, and even the natives on the west 



coast themselves have a suspicion that such is the case, 

 from the large herds of reindeer which from time to time 

 are seen to migrate across the inland ice to the west coast. 



It is most probable that the interior, if free from ice, 

 is like a North European high plateau, with a flora far 

 more copious than that of the coast. 



But this I maintain, that whether the interior of 

 Greenland is richly covered with forests, as the land 

 round the frigid pole of Siberia, or is a treeless, ice-free 

 tundra, or even a desert of perpetual ice, the solution of 

 the problem of its real nature is so important, and of 

 such consequence to science, that there could hardly, 

 at the present moment, be conceived an object more 

 worthy of an Arctic expedition than to ascertain 

 the true conditions of the interior of this particular 

 country. 



Besides the object of penetrating to the interior of 

 Greenland, the expedition will have several others in 

 view, of which I may mention the principal : — 



To Fix the Limit of the Drift-ice between Iceland and 

 Cape Farewell, and to take Soundings and Dredgings 

 in the Adjacent Seas 



This part of the Atlantic has hardly ever been subjected 

 to any other kind of examination than that made on 

 laying the first cables. A knowledge of the same is, 

 however, of great importance, both for completing the 

 missing link in the hydrographic chain of the Ocean 

 dividing Europe and America, and for the discovery of 

 the causes of the change in the ice-conditions in the 

 seas of the east coast which seem to have taken place 

 since Greenland was first discovered. Without much 

 waste of time the expedition may be occupied with these re- 

 searches during the voyage from Iceland to the Greenland 

 promontory, which will take place in a season when fine 

 weather may be presumed to reign here, while they may, 

 although with less probability of being favoured by this 

 condition, be effected during the return journey. 



The Collection of Fresh Specimens of the Flora of the Ice 

 and Snow 

 Professor Wittrock is at present engaged in publishing 

 a very interesting and important work on the microscopic 

 flora, with several varieties, whose home is in the snow 

 and ice-fields of the Alps and the Polar regions, for 

 which materials have been brought home from the latter 

 by the Swedish Arctic expeditions. My expedition 

 will, during the coming visit to Greenland, be in a position 

 to gather further materials for researches, which have 

 already revealed to us the startling fact, that even snow 

 and ice can form the bed for a flora regular in development, 

 and of many varieties. 



