Notice of Prof. Forbes' 's Travels in the Alps. 179 



and strengthened his recollections by successive visits during a part of 

 ten summers, to almost every district of the Alps between Provence and 

 Austria. He has crossed the principal chain of the Alps twenty-seven 

 times, generally on foot, by twenty-three different passes, and he has in- 

 tersected the lateral chains in many directions. - Unlike De Saussure, 

 who frequently in his annual journeys travelled with ten or twelve men, 

 as attendants, and four to six mules of burden — or Prof. Hugi, of Soleure, 

 who often had with him twelve to fifteen companions and guides, largely 

 paid, the Scotch professor pursued his inquiries almost alone. He 

 employed neither draughtsman, surveyor, or naturalist. Every thing 

 that it was possible to do, he executed with his own hands, noted the 

 result on the spot, and extended it as speedily as possible afterwards. 

 His only assistant was Auguste Balmat, a very intelligent and worthy 

 guide of Chamouni. The work of Prof. Forbes is sustained by very 

 recent observations. He spent the latter part of June, 1842, at the 

 Montanvert, (Chamouni,) the first half of July on the southern side 

 of Mount Blanc, and in Piedmont. Returning by the Montanvert, 

 by the Col du Geant, he continued his experiments on the Mer de 

 Glace, until the ninth of August. He then, in company a part of the 

 time with Prof. Struder, passed a month in visiting Monte Rosa and the 

 adjacent country, and finished September on or near the glacier at 

 Chamouni. 



His last date, in a communication from his faithful guide, Balmat, is 

 even as late as June 8th, 1843 — six months from this date, (December 

 8th, 1843.) The information relates to the descent of the ice near the 

 Montanvert, which during the preceding nine months had been at the 

 rate of nearly fifteen inches for twenty-four hours. 



Snow line and glaciers. — High mountains are in every zone covered 

 with snow ; — the atmosphere grows colder and colder the higher we as- 

 cend into it, and therefore in ascending a high hill or mountain we pass 

 through a succession of climates. " While the plains are covered with 

 the verdure of summer, eternal winter reigns upon the summits ; and 

 thus the stupendous ranges of the Himalaya or the Andes present, in 

 one wonderful picture, all the climates of the earth, from the tropics to 

 the poles." 



At the equator, the snow is permanent at 16,000 feet, a little more 

 than three miles above the level of the sea. In the Swiss Alps, the 

 snow line is 8,700 feet high. In very high latitudes, the snow line comes 

 down to the sea level ; — in such countries snow is the natural covering 

 of the earth, and the very soil is frozen to an increasing depth. In the 

 warm season snow melts in every climate ; and if the snow which falls 

 in one season is just melted and no more, then the snow line is station- 

 ary — if all that falls is not melted, then this line advances — and if more 

 is melted, then it recedes. 



