The fact of the cold increasing as we ascend mountains is due in part to the greater rarity of the atmosphere in the higher regions, and to their greater distance from the radiated beat of the plains ; never theless the particular aspect of various parts of mountains as regards the sun, and the conformation of the higher valleys, greatly modify the cold of particular places ; and a much greater heat is sometimes experienced in a high valley than is felt in one much lower down. To this circumstance is due in part the seeming anomalies that are met with in the habitation of plants, many being found at heights where they would be little expected.
Though mountains are such striking objects, and, when contemplated only with respect to their absolute elevation above the sea, appear to be enormous protuberances on the earth's surface, they are very incon siderable when compared with the whole mass of the globe. The habitable parts of the earth, at least those where population is most dense, and in which human industry is most concentrated, all lie within a few hundred feet above the sea, which may be regarded as a part of the true surface of the sphere. But even the height of the loftiest mountains, which is about five miles, is only about one eight-hundredth part of the radius of the earth. In books of travels we often find the distance mentioned at which a particular mountain is visible. As assertions of this kind are sometimes loosely made, the following rule will serve for roughly estimating the distance at which a mountain of known height can be seen from the surface of the sphere : multiply the square root of the height of the mountain in feet by 1•2247; the product will be the distance in miles at which the mountain is visible.
With regard to the heights of nrountains it may be observed that they vary considerably. Some authors, however, regard every eminence below 1000 feet as a hill. Since the application of the ,barometer to the admeasuretnent of heights, there are few mountains of any import ance, in Europe at least, whose elevation above the sea is not now known and registered. A list of the principal mountain heights on the globe would fill a volume. It may be sufficient here to give the heights of the principal peaks of some of the more important chains.
Earepe.—Mont Blanc, highest point of the Alps, and of Europe, 15,744 feet ; Mont Perdu, Pyrenees, 10,994 7moute Como, Apennines, 9523; Lomita, Carpathians, 8799; Sneehetta, Dovrefleld, Norway, 8122; 31ulhacen, Sierra Nevada, Spain, 11,483 ; I'uy de Sand, Auvergne, France, 6200; Mont Mezin, Cevennes, France, 5795; 'Etna, Sicily, 10,870 ; Olympus, Greece, 9754; Veauvius, 3917.
British greater number of the heights about to he stated, are derived from a table of the ' Altitudes above the mean level of the sea of the stations composing the principal Triangulation' of the.Ordnance Trigonometrical Survey of Great Britain and Ireland, given in the account of that triangulation recently produced by Captain A. R. Clarke, lt.E., under the direction of Colonel Sir Henry James,
R.E., F.R.S., Superintendent of the Survey, London, 1858. The altitudes of a few stations but little elevated above the sea, are in cluded for comparison. Fractions of a foot are either omitted, or reckoned as an entire foot, except in heights below 1000 feet, in which they are given.
Enjland.—Sca Fell, highest point in England, 3229; Helvellyn, 3055 ; Skiddaw, 3038; Croat; Fell, 2928 ; Cheviot, 2669 ; Coniston Fell, 2575 ; Ingleborough, 2373 ; Great Whernside, 2310; Malvern, 1396; Mendip, 9791; Inkpen Ileaccin, the loftiest summit of the chalk formation, 972.8; Leith Hill, 967; Fairlight Down, 5831 ; Beachy Head, 532•4; Lundy Island, 466; St. Paul's Cathedral, top of cross, 417'9; Severndroog Castle, Shooter's Hill, ground, Epping Poorhouse, 371'2 ; Greenwich Observatory, vane, 214; Ordnance Map Office, Southampton, 78; York Minster, ground, 53 ; Ely Minster, ground, Norwich Cathedral spire, ground, 19.7.
Wales.—Snewdon, highest point in the principality, 3590; Cam Llewellen, 3171 ; Caster Idris, 2959; Great Orme'll Head, 6831.
Nevis, highest point in the British Isles, 4406 ; Ben 3lacdui, 4296 ; Ben Lawers, 3934; Ben Lomond, 3192; Sehehallien, 3564; Ben More, Mull, 3185 ; Ben More, South Uist, 2034.
Ireland.—Carran Tual, Kerry, highest point in Ireland (?), 3412, doubtful ; Shove Donard, 2788 ; Nephin, 2638; Mourne Mountains, 2493, doubtful ; Howth, 555.
Asia.—Mount Everest, Nepaul, 29,002 (highest mountain known, measured by Colonel Waugh); Kunchin-junga, Sikkim, W. part, 28,178, E. peak, 27,826 ; Dhawalagiri, Nepaul, 26,862; Juwabir, 25,670. These are peaks of the Himalaya. Ophir, Sumatra, 13,840 ; Mowna Roa, Sandwich Islands, 13,760; Egmont, New Zealand, 8840; Italitskoi, Altaian chain, 10,735; Ararat, Armenia, 17,212; Arjish, Anatolia, 10,000? ; Olympus, Anatolia, 6500; Lebanon, Palestine, 9517; Awatska, a volcano in Kamtehatka, 12.000 feet.
Africa.—Kilimandjaro, lat. 4°•0' S. in the true Mountains of the Moon, 20,000 1; Abba Jarat, Abyssinia, 15,008 ; Geesh, in Abyssinia, 15,000 ? ; Peak of Teyde, Teneriffe, a volcano, 12,205; highest peak of Atlas chain, 12,000, and perhaps more; Table Mountain, 3816.
America.—Aeoncagua, Chile, (highest point in America ?) 23,910 ; Illimani (the richest gold mountain of Peru), 21,140 • Chimboraco, Andes, 21,421; Antisana, 19,136; Cotopaxi, 18,775; 15,931 ; Popocatepetl, Mexico, 17.720: the last four are volcanoes. Mount St. Elias, U.S., 17,850 ; Fremont's Peak, Rocky Mountains, 13,570; Mount Washington, Appalachians, 6428.
Mount Terror, 13,384; Mount Erebus, 12,367 ; both in the antarctic lands.
The particular history of important ranges of mountains, as Aars, ALTAI, &c., will be found in ClE00. Dcv. under their names, respectively, or under those of the countries to which they belong.