After considering the four great mountain systems of Asia, which, in their normal geognostic character, are true parallel chains, we must turn to the long series of alternating elevations following a direction from north to south, and which extend from Cape Comorin, opposite to the island of Ceylon, to the Icy Sea, alternating between the parallels of 66° and 77° east longitude, from S.S.E. to N.N.W. To this system of meridian chains, whose alternations remind us of faults in veins, belong the Ghauts, the Soliman chain, the Paralasa, the Bolor, and the Ural range. This interruption of the profile of the elevation is so constituted, that each new chain begins in a degree of latitude beyond that to which the preceding one had attained, all alternating successively in an opposite direction. The importance which the Greeks (probably not earlier than the second century of our era) attached to these chains running from north to south, induced Agathodæmon and Ptolemy (Tab. vii. et viii.) to regard the Bolor under the name of Imaus as an axis of elevation, which extended as far as 62° north latitude into the basin of the lower Irtysch and Obi.[[CE]]
As the vertical height of mountain summits above the sea’s level (however unimportant the phenomenon of the more or less extensive folding of the crust of a planetary sphere may be in the eyes of geognosists) will always continue, like all that is difficult of attainment, to be an object of general curiosity, the present would appear to furnish a fitting place for the introduction of an historical notice relative to the gradual advance of hypsometric knowledge. When I returned to Europe in 1804, after an absence of four years, not one of the high snow-crowned summits of Asia (in the Himalaya, the Hindoo-Coosh, or the Caucasus) had been yet measured with any degree of accuracy. I was unable, therefore, to compare my determinations of the heights of perpetual snow in the Cordilleras of Quito or the mountains of Mexico, with any results obtained in India. The important travels of Turner, Davis, and Saunders to the highlands of Thibet, were indeed accomplished in the year 1783; but the intelligent Colebrooke justly observed that the height of the Schamalari (28° 5′ north latitude, 89° 30′ east longitude, somewhat north of Tassisudan), as given by Turner, rested on a foundation quite as slight as the assumed measurements of the heights seen from Patna and Kafiristan by Colonel Crawford and Lieutenant Macartney.[[CF]] The admirable labours of Webb, Hodgson, Herbert, and the brothers Gerard, have indeed thrown considerable light on the question concerning the heights of the colossal summits of the Himalaya; but yet, in 1808, the hypsometric knowledge of the East Indian mountain chains was still so uncertain, that Webb wrote to Colebrooke, “The height of the Himalaya still remains undetermined. It is true that I have ascertained that the summits visible from the elevated plains of Rohilkand are 21,000 feet higher than that plateau, but we are ignorant of their absolute height above the sea.”
In the year 1820 it first began to be currently reported in Europe that there were not only much higher summits in the Himalaya than in the Cordilleras, but that Webb had seen in the pass of Niti, and Moorcroft in the Thibetian plateau of Daba, and the sacred lakes, fine corn-fields and fertile pasturelands at elevations far exceeding the height of Mont Blanc. This announcement was received in England with great incredulity, and opposed by doubts regarding the influence of the refraction of light. I have shown the unsoundness of such doubts in two printed treatises on the mountains of India, in the Annales de Chimie et de Physique. The Tyrolese Jesuit, Father Tiefenthaler, who in 1766 penetrated as far as the provinces of Kemaun and Nepal, had already divined the importance of the Dhawalagiri. We read on his map: “Montes Albi, qui Indis Dolaghir, nive obsiti.” Captain Webb always employs the same name. Until the measurements of the Djawahir (30° 22′ north latitude, and 79° 58′ east longitude, 26,902 feet in elevation), and of the Dhawalagiri (28° 40′ north latitude, and 83° 21′ east longitude, 28,072 feet in elevation), were made known in Europe, the Chimborazo, which, according to my trigonometrical measurement, was 21,422 feet in height,[[CG]] was still everywhere regarded as the loftiest summit on the earth. The Himalaya appeared, therefore, at that time, to be 4323 feet or 6620 feet higher than the Cordilleras, according as the comparison was made with the Djawahir or the Dhawalagiri. Pentland’s South American travels, in the years 1827 and 1838, directed attention to two snow-crowned summits of Upper Peru, east of the lake of Titicaca, which were conjectured to be respectively 3824 and 2578 feet higher than the Chimborazo.[[CH]] It has been already observed,[[CI]] that the most recent computations in the measurements of the Sorata and Illimani have shown the error of this hypsometric assertion. The Dhawalagiri, therefore, on whose declivity in the river-valley of Ghandaki, the Salagrana Ammonites, so celebrated in the Brahminical ritual as symbols of the testaceous incarnation of Vishnu, are collected, still indicates a difference of elevation between both continents of more than 6600 feet.
The question has been asked, whether there may not be still greater heights in the rear of the southernmost chain, which has been as yet measured with more or less exactitude. Colonel George Lloyd, who in 1840 edited the important observations of Captain Alexander Gerard and his brother, entertains the opinion, that in that part of the Himalaya, which he somewhat indefinitely names the “Tartaric Chain” (and consequently in Northern Thibet, in the direction of the Kuen-lün, perhaps in the Kailasa of the sacred lakes or beyond Leh) there are mountain-summits which attain an elevation of from 29,000 to 30,000 feet, one or two thousand feet higher, therefore, than the Dhawalagiri.[[CJ]] No definite opinion can be formed on the subject until we are in the possession of actual measurements, since the indication which led the natives of Quito, long before the arrival of Bouguer and La Condamine, to regard the summit of the Chimborazo as the culminating point—or the highest point within the region of perpetual snow—is rendered very deceptive in the temperate zone of Thibet, where the radiation of the table-land is so effective, and where the lower limit of perpetual snow does not constitute a regular line of equal level as in the tropics. The greatest elevation above the level of the sea that has been reached by man on the sides of the Himalaya is 19,488 feet. This elevation was gained by Captain Gerard, with seven barometers, as we have already observed, on the mountain of Tarhigang, somewhat to the north-west of Schipke.[[CK]] This happens to be almost the same height as that to which I myself ascended up on the Chimborazo (on the 23rd of June, 1802), and which was reached thirty years later (16th of December, 1831) by my friend Boussingault. The unattained summit of the Tarhigang is, moreover, 1255 feet higher than the Chimborazo.
The passes across the Himalaya from Hindostan to Chinese Tartary, or rather to Western Thibet, especially between the rivers Buspa and Schipke, or Langzing Khampa, are from 15,347 to 18,544 feet in height. In the chain of the Andes I found that the pass of Assuay, between Quito and Cuenca, at the Ladera de Cadlud, was also fully 15,566 feet above the level of the sea. A great part of the Alpine plains of the interior of Asia would lie buried throughout the whole year in snow and ice, if the limits of perpetual snow were not singularly elevated, probably to about 16,626 feet, by the force of the heat radiated from the Thibetian plain, the constant serenity of the sky, the rarity of the formation of snow in the dry atmosphere, and by the powerful solar heat peculiar to the eastern continental climate, which characterizes the northern declivity of the Himalaya. Fields of barley (of Hordeum hexastichon) have been seen in Kunawur at an elevation of 14,700 feet and another variety of barley, called Ooa, and allied to Hordeum cœleste, even much higher. Wheat thrives admirably well in the Thibetian highlands, up to an elevation of 12,000 feet. On the northern declivity of the Himalaya, Captain Gerard found that the upper limits of the birch woods ascend to 14,069 feet; and small brushwood used by the natives for fuel in their huts is even found within the parallels of 30° 45′ and 31° north latitude, at an elevation of 16,946 feet, and therefore nearly 1280 feet higher than the lower snow-limit in the equatorial regions. It follows from the data hitherto collected that on the northern declivity of the Himalaya the mean of the lower snow-line is at least 16,626 feet, whilst on the southern declivity it falls to 12,980 feet. But for this remarkable distribution of heat in the upper strata of the atmosphere, the mountain plain of Western Thibet would be rendered uninhabitable for the millions of men who now occupy it.[[CL]]
In a letter which I have lately received from India from Dr. Joseph Hooker, who is engaged in meteorological and geological observations, as well as in the study of the geography of plants, he says, “Mr. Hodgson, whom we here consider more thoroughly conversant than any other geographer with the hypsometric relations of the snow ranges, recognises the correctness of the opinions you have advanced in the third part of your Asie centrale, regarding the cause of the unequal height of the limit of perpetual snow on the northern and the southern declivity of the Himalaya range. In the trans-Sutledge region (in 36° north latitude) we often observed the snow limit as high as 20,000 feet, whilst in the passes south of Brahmaputra, between Assam and Birmah (in 27° north latitude), where the most southern snow-capped mountains of Asia are situated, the snow limit sinks to 15,000 feet.” I believe we ought to distinguish between the extreme and the mean elevations, but in both we find the formerly disputed difference between the Thibetian and the Indian declivities manifested in the clearest manner.
| My result for the mean height of the snow line as given in Asie centrale, t. iii., p. 326. | Extremes according to Dr. Hooker’s Letter. | ||
|---|---|---|---|
| Feet. | Feet. | ||
| Northern declivity | 16,626 | Northern declivity | 20,000 |
| Southern declivity | 12,981 | Southern declivity | 15,000 |
| Difference | 3,645 | Difference | 5,000 |
The local differences vary still more, as may be seen from the series of extremes given in Asie centrale, t. iii., p. 295. Alexander Gerard saw the snow-limit ascend to 20,463 feet on the Thibetian declivity of the Himalaya; and Jacquemont found it as low as 11,500 feet on the south-Indian declivity, north of Cursali on the Jumnautri.
[The recent investigations of Lieutenant Strachey show that M. Humboldt has been led astray, when treating of the Himalaya, by the very authorities on whom he placed the most reliance. The results of his inquiries on this point are given in the first volume of the Cosmos (Bohn’s Ed.), pp. 9 and 338. As the subject is one of considerable interest we give a brief sketch of Lieutenant Strachey’s[[CM]] recent labours, confining ourselves to his own views, and omitting (for want of space) his somewhat lengthy exposition of the errors committed by the authorities quoted by Humboldt. The following are his personal observations regarding the southern limit of the belt of perpetual snow.
“In this part of the Himalaya it is not, on an average of years, till the beginning of December, that the snow line appears decidedly to descend for the winter. After the end of September, indeed, when the rains are quite over, light falls of snow are not of very uncommon occurrence on the higher mountains, even down to 12,000 feet; but their effects usually disappear very quickly, often in a few hours. The latter part of October, the whole of November, and the beginning of December, are here generally characterised by the beautiful serenity of the sky; and it is at this season, on the southern edge of the belt, that the line of perpetual snow is seen to attain its greatest elevation.