Books: Himalayan Journals (Complete)
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J. D. Hooker >> Himalayan Journals (Complete)
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The great accumulation of snow at 15,000 feet, in the parallel of P,
exercises a decided influence on the vegetation. The alpine
rhododendrons hardly reach 14,000 feet in the broad valleys and
round-headed spurs of the mountains of the Tunkra and Chola passes;
whilst the same species ascend to 16,000, and one to 17,000 feet, at
T. Beyond the latter point, again, the great aridity of the climate
prevents their growth, and in Tibet there are generally none even as
low as 12,000 and 14,000 feet. Glaciers, again, descend to 15,000
feet in the tortuous gorges which immediately debouch from the snows
of Kinchinjunga, but no plants grow on the debris they carry down,
nor is there any sward of grass or herbage at their base, the
atmosphere immediately around being chilled by enormous accumulations
of snow, and the summer sun rarely warming the soil. At T, again, the
glaciers do not descend below 16,000 feet, but a greensward of
vegetation creeps up to their bases, dwarf rhododendrons cover the
moraines, and herbs grow on the patches of earth carried down by the
latter, which are thawed by the more frequent sunshine, and by the
radiation of heat from the unsnowed flanks of the valleys down which
these ice-streams pour.
Looking eastward or westward on the map of India, we perceive that
the phenomenon of perpetual snow is regulated by the same laws.
From the longitude of Upper Assam in 95 degrees E to that of Kashmir
in 75 degrees E, the lowest limit of perpetual snow is 15,500 to
16,000 feet, and a shrubby vegetation affects the most humid
localities near it, at 12,000 to 14,000 feet. Receding from the
plains of India and penetrating the mountains, the climate becomes
drier, the snowline rises, and vegetation diminishes, whether the
elevation of the land increases or decreases; plants reaching 17,000
and 18,000 feet, and the snow-line, 20,000 feet. To mention extreme
cases; the snow-level of Sikkim in 27 degrees 30 minutes is at 16,000
feet, whereas in latitude 35 degrees 30 minutes Dr. Thomson found the
snow line 20,000 feet on the mountains near the Karakoram Pass, and
vegetation up to 18,500 feet--features I found to be common also to
Sikkim in latitude 28 degrees.
The Himalaya, north of Nepal, and thence eastward to the bend of the
Yaru-Tsampu (or Tibetan Burrampooter) has for its geographical limits
the plains of India to the south, and the bed of the Yaru to the
north. All between these limits is a mountain mass, to which Tibet
(though so often erroneously called a plain)* [The only true account
of the general features of eastern Tibet is to be found in MM. Huc
and Gabet's travels. Their description agrees with Dr. Thomson's
account of western Tibet, and with my experience of the parts to the
north of Sikkim, and the information I everywhere obtained.
The so-called _plains_ are the flat floors of the valleys, and the
terraces on the margins of the rivers, which all flow between
stupendous mountains. The term "maidan," so often applied to Tibet by
the natives, implies, not a plain like that of India, but simply an
open, dry, treeless country, in contrast to the densely wooded wet
regions of the snowy Himalaya, south of Tibet.] forms no exception.
The waters from the north side of this chain flow into the Tsampu,
and those from the south side into the Burrampooter of Assam, and the
Ganges. The line, however tortuous, dividing the heads of these
waters, is the watershed, and the only guide we have to the axis of
the Himalaya. This has never been crossed by Europeans, except by
Captain Turner's embassy in 1798, and Captain Bogle's in 1779, both
of which reached the Yaru river. In the account published by Captain
Turner, the summit of the watershed is not rigorously defined, and
the boundary, of Tibet and Bhotan is sometimes erroneously taken for
it; the boundary being at that point a southern spur of Chumulari.*
[Between Donkia and Chumulari lies a portion of Tibet (including the
upper part of the course of the Machoo river) bounded on the east by
Bhotan, and on the west by Sikkim (see chapter xxii). Turner, when
crossing the Simonang Pass, descended westwards into the valley of
the Machoo, and was still on the Indian watershed.] Eastwards from
the sources of the Tsampu, the watershed of the Himalaya seems to
follow a very winding course, and to be everywhere to the north of
the snowy peaks seen from the plains of India. It is by a line
through these snowy peaks that the axis of the Himalaya is
represented in all our maps; because they _seem_ from the plains to
be situated on an east and west ridge, instead of being placed on
subsidiary meridional ridges, as explained above. It is also across
or along the subsidiary ridges that the boundary line between the
Tibetan provinces and those of Nepal, Sikkim, and Bhotan, is usually
drawn; because the enormous accumulations of snow form a more
efficient natural barrier than the greater height of the less snowed
central part of the chain beyond them.
Though, however, our maps draw the axis through the snowy peaks,
they also make the rivers to rise beyond the latter, on the northern
slopes as it were, and to flow southwards through gaps in the axis.
Such a feature is only reconcilable with the hypothesis of the chain
being double, as the Cordillera of Peru and Chili is said to be,
geographically, and which in a geological sense it no doubt is: but
to the Cordillera the Himalaya offers no parallel. The results of
Dr. Thomson's study of the north-west Himalaya and Tibet, and
my own of the north-east extreme of Sikkim and Tibet, first gave
me an insight into the true structure of this chain. Donkia mountain
is the culminant point of an immensely elevated mass of mountains, of
greater mean height than a similarly extensive area around Kinchin
junga. It comprises Chumulari, and many other mountains much
above 20,000 feet, though none equalling Kinchinjunga, Junnoo, and
Kubra. The great lakes of Ramchoo and Cholamoo are placed on it; and
the rivers rising on it flow in various directions; the Painomchoo
north-west into the Yaru; the Arun west to Nepal; the Teesta south-
west through Sikkim; the Machoo south, and the Pachoo south-east,
through Bhotan. All these rivers have their sources far beyond the
great snowed mountains, the Arun most conspicuously of all, flowing
completely at the back or north of Kinchinjunga. Those that flow
southwards, break through no chain, nor do they meet any contraction
as they pass the snowy parts of the mountains which bound the valleys
in which they flow, but are bound by uniform ranges of lofty
mountains, which become more snowy as they approach the plains of
India. These valleys, however, gradually contract as they descend,
being less open in Sikkim and Nepal than in Tibet, though there
bounded by rugged mountains, which from being so bare of snow and of
vegetation, do not give the same impression of height as the isolated
sharper peaks which rise out of a dense forest, and on which the snow
limit is 4,000 or 5,000 feet lower.
The fact of the bottom of the river valleys being flatter towards the
watershed, is connected with that of their fall being less rapid at
that part of their course; this is the consequence of the great
extent in breadth of the most elevated portion of the chain. If we
select the Teesta as an example, and measure its fall at three points
of its course, we shall find the results very different. From its
principal source at Lake Cholamoo, it descends from 17,000 to 15,000
feet, with a fall of 60 feet to the mile; from 15,000 to 12,000 feet,
the fall is 140 feet to the mile; in the third part of its course it
descends from 12,000 to 5000 feet, with a fall of 160 feet to the
mile; and in the lower part the descent is from 5000 feet to the
plains of India at 300 feet, giving a fall of 50 feet to the mile.
There is, however, no marked limit to these divisions; its valley.
gradually contracts, and its course gradually becomes more rapid.
It is worthy of notice that the fall is at its maximum through that
part of its valley of which the flanks are the most loaded with snow;
where the old moraines are very conspicuous, and where the present
accumulations from landslips, etc., are the most extensive.* [It is
not my intention to discuss here the geological bearings of this
curious question; but I may state that as the humidity of the climate
of the middle region of the river-course tends to increase the fall
in a given space, so I believe the dryness of the climate of the
loftier country has the opposite effect, by preserving those
accumulations which have raised the floors of the valleys and
rendered them level.]
With reference to Kinchinjunga, these facts are of importance, as
showing that mere elevation is in physical geography of secondary
importance. That lofty mountain rises from a spur of the great range
of Donkia, and is quite removed from the watershed or axis of the
Himalaya, the rivers which drain its northern and southern flanks
alike flowing to the Ganges. Were the Himalaya to be depressed 18,000
feet, Kubra, Junnoo, Pundim, etc., would form a small cluster of
rocky islands 1000 to 7000 feet high, grouped near Kinchinjunga,
itself a cape 10,000 feet high, which would be connected by a low,
marrow neck, with an extensive and mountainous tract of land to its
north-east; the latter being represented by Donkia. To the north of
Kinchin a deep bay or inlet would occupy the present valley of the
Arun, and would be bounded on the north by the axis of the Himalaya,
which would form a continuous tract of land beyond it. Since writing
the above, I have seen Professor J. Forbes's beautiful work on the
glaciers of Norway: it fully justifies a comparison of the Himalaya
to Norway, which has long been a familiar subject of theoretical
enquiry with Dr. Thomson and myself. The deep narrow valleys of
Sikkim admirably represent the Norwegian fiords; the lofty, rugged,
snowy mountains, those more or less submerged islands of the
Norwegian coast; the broad rearward watershed, or axis of the chain,
with its lakes, is the same in both, and the Yaru-tsampu occupies the
relative position of the Baltic.
Along the whole chain of the Himalaya east of Kumaon there are, I
have no doubt, a succession of such lofty masses as Donkia, giving
off stupendous spurs such as that on which Kinchin forms so
conspicuous a feature. In support of this view we find every river
rising far beyond the snowy peaks, which are separated by
continuously unsnowed ranges placed between the great white masses
that these spurs present to the observer from the south.* [At vol. i.
chapter viii, I have particularly called attention to the fact, that
west of Kinchinjunga there is no continuation of a snowy Himalaya, as
it is commonly called. So between Donkia and Chumulari there is no
perpetual snow, and the valley of the Machoo is very broad, open, and
comparatively flat.] From the Khasia mountains (south-east of Sikkim)
many of these groups or spurs were seen by Dr. Thomson and myself, at
various distances (80 to 210 miles); and these groups were between
the courses of the great rivers the Soobansiri, Monass, and Pachoo,
all east of Sikkim. Other masses seen from the Gangetic valley
probably thus mark the relative positions of the Arun, Cosi, Gunduk,
and Gogra rivers.
Another mass like that of Chumulari and Donkia, is that around the
Mansarowar lakes, so ably surveyed by the brothers Captains R. and H.
Strachey, which is evidently the centre of the Himalaya. From it the
Gogra, Sutlej, Indus, and Yaru rivers all flow to the Indian side of
Asia; and from it spring four chains, two of which are better known
than the others. These are:--1. The eastern Himalaya, whose axis runs
north of Nepal, Sikkim, and Bhotan, to the bend of the Yaru, the
valley of which it divides from the plains of India. 2. The
north-west Himalaya, which separates the valley of the Indus from the
plains of India. Behind these, and probably parallel to them, lie two
other chains. 3. The Kouenlun or Karakoram chain, dividing the Indus
from the Yarkand river. 4. The chain north of the Yaru, of which
nothing is known. All the waters from the two first of these chains,
flow into the Indian Ocean, as do those from the south faces of the
third and fourth; those from the north side of the Kouenlun, and of
the chain north of the Yaru, flow into the great valley of Lake Lhop,
which may once have been continuous with the Amoor river.* [The
Chinese assert that Lake Lhop once drained into the Hoang-ho; the
statement is curious, and capable of confirmation when central Asia
shall have been explored.]
For this view of the physical geography of the western Himalaya and
central Asia, I am indebted to Dr. Thomson. It is more consonant with
nature, and with what we know of the geography of the country and of
the nature of mountain chains, than that of the illustrious Humboldt,
who divides central Asia by four parallel chains, united by two
meridional ones; one at each extremity of the mountain district.
It follows in continuation and conclusion of our view that the
mountain mass of Pamir or Bolor, between the sources of the Oxus and
those of the Yarkand river, may be regarded as a centre from which
spring the three greatest mountain systems of Asia. These are:--1. A
great chain, which runs in a north-easterly direction as far as
Behring's Straits, separating all the rivers of Siberia from those
which flow into the Pacific Ocean. 2. The Hindoo Koosh, continued
through Persia, and Armenia into Taurus. And, 3. The Muztagh or
Karakorum, which probably extends due east into China, south of the
Hoang-ho, but which is broken up north of Mansarowar into the chains
which have been already enumerated.
APPENDIX F.
ON THE CLIMATE OF SIKKIM.
The meteorology of Sikkim, as of every part of the Himalayan range,
is a subject of growing interest and importance; as it becomes yearly
more necessary for the Government to afford increased facilities for
a residence in the mountains to Europeans in search of health, or of
a salubrious climate for their families, or for themselves on
retirement from the exhausting service of the plains. I was therefore
surprised to find no further register of the weather at Dorjiling,
than an insufficient one of the rain-fall, kept by the medical
officer in charge of the station; who, in this, as in all similar
cases,* [The government of India has gone to an immense expense, and
entailed a heavy duty upon its stationary medical officers, in
supplying them with sometimes admirable, but more often very
inaccurate, meteorological instruments, and requiring that daily
registers be made, and transmitted to Calcutta. In no case have I
found it to be in the officer's power to carry out this object; he
has never time, seldom the necessary knowledge and experience, and
far too often no inclination. The majority of the observations are in
most cases left to personal native or other servants, and the
laborious results I have examined are too frequently worthless.] has
neither the time nor the opportunity to give even the minimum of
required attention to the subject of meteorology. This defect has
been in a measure remedied by Dr. Chapman, who kept a twelve-months'
register in 1837, with instruments carefully compared with Calcutta
standards by the late James Prinsep, Esq., one of the most
accomplished men in literature and science that India ever saw.
The annual means of temperature, rain-fall, etc., vary greatly in the
Himalaya; and apparently slight local causes produce such great
differences of temperature and humidity, that one year's observations
taken at one spot, however full and accurate they may be, are
insufficient: this is remarkably the case in Sikkim, where the
rainfall is great, and where the difference between those of two
consecutive years is often greater than the whole annual London fall.
My own meteorological observations necessarily form but a broken
series, but they were made with the best instruments, and with a view
to obtaining results that should be comparable _inter se,_ and with
those of Calcutta; when away from Dorjiling too, in the interior of
Sikkim, I had the advantage of Mr. Muller's services in taking
observations at hours agreed upon previous to my leaving, and these
were of the greatest importance, both for calculating elevations, and
for ascertaining the differences of temperature, humidity, diurnal
atmospheric tide, and rain-fall; all of which vary with the
elevation, and the distance from the plains of India.
Mr. Hodgson's house proved a most favourable spot for an observatory,
being placed on the top of the Dorjiling spur, with its broad
verandah facing the north, in which I protected the instruments from
radiation* [This is a most important point, generally wholly
neglected in India, where I have usually seen the thermometer hung in
good shade, but exposed to reflected heat from walls, gravel walks,
or dry earth. I am accustomed from experience to view all extreme
temperatures with great suspicion, on this and other accounts. It is
very seldom that the temperature of the free shaded air rises much
above 100 degrees, except during hot winds, when the lower stratum
only of atmosphere (often loaded with hot particles of sand), sweeps
over the surface of a soil scorched by the direct rays of the sun.]
and wind. Broad grass-plots and a gravel walk surrounded the house,
and large trees were scattered about; on three sides the ground
sloped away, while to the north the spur gently rose behind.
Throughout the greater part of the year the prevailing wind is from
the south-east, and comes laden with moisture from the Bay of Bengal:
it rises at sunrise, and its vapours are early condensed on the
forests of Sinchul; billowy clouds rapidly succeed small patches of
vapour, which rolling over to the north side of the mountain, are
carried north-west, over a broad intervening valley, to Dorjiling.
There they bank on the east side of the spur, and this being
partially clear of wood, the accumulation is slow, and always first
upon the clumps of trees. Very generally by 9 a.m., the whole eastern
sky, from the top of Dorjiling ridge, is enveloped in a dense fog,
while the whole western exposure enjoys sunshine for an hour or two
later. At 7 or 8 a.m., very small patches are seen to collect on
Tonglo, which gradually dilate and coalesce, but do not shroud the
mountain for some hours, generally not before 11 a.m. or noon.
Before that time, however, masses of mist have been rolling over
Dorjiling ridge to the westward, and gradually filling up the
valleys, so that by noon, or 1 p.m., every object is in cloud.
Towards sunset it falls calm, when the mist rises, first from
Sinchul, or if a south-east wind sets in, from Tonglo first.
The temperature is more uuiform at Mr. Hodgson's bungalow, which is
on the top of the Dorjiling ridge, than on either of its flanks; this
is very much because a good deal of wood is left upon it, whose cool
foliage attracts and condenses the mists. Its mean temperature is
lower by nearly 22 degrees than that of Mr. Muller's and Dr.
Campbell's houses, both situated on the slopes, 400 feet below.
This I ascertained by numerous comparative observations of the
temperature of the air, and by burying thermometers in the earth it
is chiefly to be accounted for by the more frequent sunshine at the
lower stations, the power of the sun often raising the thermometer in
shade to 80 degrees, at Mr. Muller's; whereas during the summer I
spent at Mr. Hodgson's it never rose much above 70 degrees, attaining
that height very seldom and for a very short period only. The nights,
again, are uniformly and equally cloudy at both stations, so that
there is no corresponding cold of nocturnal radiation to reduce
the temperature.
The mean decrease of temperature due to elevation, I have stated
(Appendix I.) to be about 1 degree for every 300 feet of ascent;
according to which law Mr. Hodgson's should not be more than 1.5
degrees° colder than Mr. Muller's. These facts prove how difficult it
is to choose unexceptionable sites for meteorological observatories
in mountainous countries; discrepancies of so great an amount being
due to local causes, which, as in this case, are perhaps transient;
for should the top of the spur be wholly cleared of timber, its
temperature would be materially raised; at the expense, probably, of
a deficiency of water at certain seasons. Great inequalities of
temperature are also produced by ascending currents of heated air
from the Great Rungeet valley, which affect certain parts of the
station only; and these raise the thermometer 10 degrees (even when
the sun is clouded) above what it indicates at other places of
equal elevation.
The mean temperature of Dorjiling (elev. 7,430 feet) is very nearly
50 degrees, or 2 degrees higher than that of London, and 26 degrees
below that of Calcutta (78 degrees,* [Prinsep, in As. Soc. Journ.,
Jan. 1832, p. 30.] or 78.5 degrees in the latest published tables*
[Daniell's Met. Essays, vol. ii. p. 341.]); which, allowing 1 degree
of diminution of temperature for every degree of latitude leaves
1 degree due to every 300 feet of ascent above Calcutta to the height
of Dorjiling, agreeably to my own observations. This diminution is
not the same for greater heights, as I shall have occasion to show in
a separate chapter of this Appendix, on the decrement of heat
with elevation.
A remarkable uniformity of temperature prevails throughout the year
at Dorjiling, there being only 22 degrees difference between the mean
temperatures of the hottest and coldest months; whilst in London,
with a lower mean temperature, the equivalent difference is 27
degrees. At 11,000 feet this difference is equal to that of London.
In more elevated regions, it is still greater, the climate becoming
excessive at 15,000 feet, where the difference amounts to 30 degrees
at least.* [This is contrary to the conclusions of all meteorologists
who have studied the climate of the Alps, and is entirely due to the
local disturbances which I have so often dwelt upon, and principally
to the unequal distribution of moisture in the loftier rearward
regions, and the aridity of Tibet. Professor James Forbes states (Ed.
Phil. Trans., v. xiv. p. 489):--1. That the decrement of temperature
with altitude is most rapid in summer: this (as I shall hereafter
show) is not the case in the Himalaya, chiefly because the warm south
moist wind then prevails. 2. That the annual range of temperature
diminishes with the elevation: this, too, is not the case in Sikkim,
because of the barer surface and more cloudless skies of the rearward
loftier regions. 3. That the diurnal range of temperature diminishes
with the height: that this is not the cane follows from the same
cause. 4. That radiation is least in winter: this is negatived by the
influence of the summer rains.] The accompanying table is the result
of an attempt to approximate to the mean temperatures and ranges of
the thermometer at various elevations.
Altitude 11,000 feet 15,000 feet 19,000 feet
Mean shade 40.9 29.8 19.8
Mean warmest month 50.0 40.0 32.0
Mean coldest month 24.0 11.0 0.0
Mean daily range
of temperature 20.0 27.0 35.0
Rain-fall in inches 40.0 20.0 10.0
1 degree equals 320 feet 350 feet 400 feet
Supposing the same formula to apply (which I exceedingly doubt) to
heights above 19,000 feet, 2 degrees would be the mean annual
temperature of the summit of Kinchinjunga, altitude 28,178 feet, the
loftiest known spot on the globe: this is a degree or two higher than
the temperature of the poles of greatest cold on the earth's surface,
and about the temperature of Spitzbergen and Melville island.
The upper limit of phenogamic vegetation coincides with a mean
temperature of 30 degrees on the south flank of Kinchinjunga, and of
22 degrees in Tibet; in both cases annuals and perennial-rooted
herbaceous plants are to be found at elevations corresponding to
these mean temperatures, and often at higher elevations in sheltered
localities. I have assumed the decrease of temperature for a
corresponding amount of elevation to be gradually less in ascending
(1 degree=320 feet at 6000 to 10,000 feet, 1 degree=400 feet at
14,000 to 18,000 feet). My observations appear to prove this, but I
do not regard them as conclusive; supposing them to be so, I
attribute it to a combination of various causes, especially to the
increased elevation and yet unsnowed condition of the mass of land
elevated above 16,000 feet, and consequent radiation of heat; also to
the greater amount of sunshine there; and to the less dense mists
which obstruct the sun's rays at all elevations. In corroboration of
this I may mention that the decrease of temperature with elevation is
much less in summer than in winter, 1 degree of Fahr. being
equivalent to only 250 feet in January between 7000 and 13,000 feet,
and to upwards of 400 feet in July. Again, at Dorjiling (7,430 feet)
the temperature hardly ever rises above 70 degrees in the summer
months, yet it often rises even higher in Tibet at 12,000 to 14,000
feet. On the other hand, the winters, and the winter nights
especially, are disproportionately cold at great heights, the
thermometer falling upwards of 40 degrees below the Dorjiling
temperature at an elevation only 6000 feet higher.
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