Ixxii REPORT — 1861'. 



It is well known that the number of days during which particular winds 

 prevail, from year to year, varies considerabl}'. Between the years 1812 and 

 1820 the Fohn was less felt in Switzerland than usual; and what was the 

 consequence? All the glaciers, during those eight or nine years, iacreased in 

 height, and crept down bolow their former limits in their respective valleys. 

 Many similar examples might be cited of the seasitiveness of the ice to slight 

 variations of temperature. Captain Godwin-Austen has lately given us a 

 description of the gigantic glaciers of the western Himalaya in those vallej-s 

 where the sources of the Indus rise, between the latitudes 35° and 3G° N. 

 The highest peaks of the Karakorum range attain in that region an elevation 

 of 28,000 feet above the sea. The glaciers, says Captain Austen, have been 

 advancing, within the memory of the living inhabitants, so as greatly to 

 encroach on the cultivated lands, and have so altered the climate of the 

 adjoining valleys immediately below, that only one crop a year can now be 

 reaped from fields which formerly yielded two crops. If such changes can 

 be experienced in less than a century, without any perceptible modification 

 in the physical geography of that part of Asia, what mighty effects may we 

 not imagine the submergence of the Sahara to have produced in adding to 

 the size of the Alpine glaciers ? If, between the years 1812 and 1820, a mere 

 diminution of the number of days during which the sirocco blew could so 

 miich promote the growth and onward movement of the ice, how much 

 greater a change would result fi-om the total cessation of the same mnd ! 

 But this would give no idea of what must have happened in the glacial 

 period ; for we cannot suppose the action of the south wind to have been sus- 

 pended: it was not in abeyance, but its character was entirely different, and 

 of an opposite nature, under the altered geographical conditions above con- 

 templated. First, instead of passing over a parched and scorching desert, 

 between the twentieth and thii-ty-fifth parallels of latitude, it woidd plenti- 

 fully absorb moisture from a sea many hundreds of miles wide. K^ext, in its 

 course over the Mediterranean, it would take up still more aqueous vapour ; 

 and when, after complete saturation, it struck the Alps, it would be diivcn 

 up into the higher and more rarefied regions of the atmosphere. There the 

 aerial current, as fast as it was cooled, would discharge its aqueous burden 

 in the form of snow, so that the same wind which is now called " the 

 devoiu'er of ice " would become its ])rincipal feeder. 



If we thus embrace Escher's theory, as accounting in no small degree for 

 the vast size of the extinct glaciers of Switzerland and Northern Italy, we 

 are by no means debarred from accc2)ting at the same time Charpentier's 

 suggestion, that the Alps in the glacial period were 2000 or 3000 feet higher 

 than they are now. Such a difference in altitude may have been an auxiliary 

 cause of the extreme cold, and seems the more probable now that we have 

 obtained unequivocal proofs of such great oscillations of level in Wales within 

 the period under consideration. We may also avail ourselves of another 

 source of refrigeration which may have coincided in time with the submer- 

 gence of the Sahara, namelj', the diversion of the Gulf-stream from its j^resent 

 course. The shape of Europe and North America, or the boundaries of sea 

 and land, depai-ted so widely in the glacial j^eriod from those now established, 

 that we cannot suppose the Gulf-stream to have taken at that period its 

 l^resent north-eastern course across the Atlantic. If it took some other 

 direction, the climate of the north of Scotland would, according to the calcu- 

 lations of ilr. Hopkins, suiter a diminution in its average annual temperature 

 of 12° E., while that of the Alps would lose 2° E. A combination of all the 

 conditions above enumerated would certainly be attended with so great a revo- 



