Chapter XXXVI: Appendix: A (1)

METEOROLOGICAL OBSERVATIONS IN BEHAR, AND IN THE VALLEYS OF THE SOANE AND GANGES.

Most of the instruments which I employed were constructed by Mr. Newman, and with considerable care: they were in general accurate, and always extremely well guarded, and put up in the most portable form, and that least likely to incur damage; they were further frequently carefully compared by myself. These are points to which too little attention is paid by makers and by travellers in selecting instruments and their cases. This remark applies particularly to portable barometers, of which I had five at various times. Although there are obvious defects in the system of adjustment, and in the method of obtaining the temperature of the mercury, I found that these instruments invariably worked well, and were less liable to derangement and fracture than any I ever used; the best proof I can give of this is that I preserved three uninjured during nearly all my excursions, left two in India, and brought a third home myself that had accompanied me almost throughout my journey.

In very dry climates these and all other barometers are apt to leak, from the contraction of the box-wood plug through which the tube passes into the cistern. This must, in portable barometers, in very dry weather, be kept moist with a sponge. A small iron bottle of pure mercury to supply leakage should be supplied with every barometer, as also a turnscrew. The vernier plate and scale should be screwed, not soldered on the metal sheath, as if an escape occurs in the barometer-case the solder is acted upon at once. A table of corrections for capacity and capillarity should accompany every instrument, and simple directions, etc., in cases of trifling derangement, and alteration of neutral point.

The observations for temperature were taken with every precaution to avoid radiation, and the thermometers were constantly compared with a standard, and the errors allowed for. The maximum thermometer with a steel index, I found to be extremely liable to derangement and very difficult to re-adjust. Negretti’s maximum thermometer was not known to me during my journey. The spirit minimum thermometers again, are easily set to rights when out of order, but in every one (of six or seven) which I took to India, by several makers, the zero point receded, the error in some increasing annually, even to –6° in two years. This seems due to a vaporisation of the spirit within the tube. I have seen a thermometer of this description in India, of which the spirit seemed to have retired wholly into the bulb, and which I was assured had never been injured. In wet-bulb observations, distilled water or rain, or snow water was used, but I never found the result to differ from that obtained by any running fresh water, except such as was polluted to the taste and eye.

The hours of observation selected were at first sunrise, 9 a.m., 3 p.m., sunset, and 9 p.m., according to the instructions issued to the Antarctic expedition by the Royal Society. In Sikkim, however, I generally adopted the hours appointed at the Surveyor General’s office, Calcutta; viz., sunrise, 9h. 50m. a.m., noon, 2h. 40m. p.m., 4 p.m., and sunset, to which I added a 10 p.m. observation, besides many at intermediate hours as often as possible. Of these the 9h. 50m. a.m. and 4 p.m. have been experimentally proved to be those of the maximum and minimum of atmospheric pressure at the level of the sea in India, and I did not find any great or marked deviation from this at any height to which I attained, though at 15,000 or 16,000 feet the morning maximum may occur rather earlier.

The observations for nocturnal (terrestrial) radiation were made by freely suspending thermometers with naked bulbs, or by laying them on white cotton, wool, or flannel; also by means of a thermometer placed in the focus of a silvered parabolic reflector. I did not find that the reflector possessed any decided advantage over the white cotton: the means of a number of observations taken by each approximated closely, but the difference between individual observations often amounted to 2°.

Observations again indicative of the radiation from grass, whether dewed or dry, are not strictly comparable; not only does the power of radiation vary with the species, but much more with the luxuriance and length of the blades, with the situation, whether on a plane surface or raised, and with the subjacent soil. Of the great effect of the soil I had frequent instances; similar tufts of the same species of grass radiating more powerfully on the dry sandy bed of the Soane, than on the alluvium on its banks; the exposure being equal in both instances. Experiments for the surface-temperature of the soil itself, are least satisfactory of any:—adjoining localities being no less affected by the nature, than by the state of disintegration of the surface, and by the amount of vegetation in proximity to the instrument.

The power of the sun’s rays in India is so considerable, and protracted through so long a period of the day, that I did not find the temperature of springs, or of running water, even of large deep rivers, so constant as was to be expected.

The temperature of the earth was taken by sinking a brass tube a yard long in the soil.

A thermometer with the bulb blackened affords the only means the traveller can generally compass, of measuring the power of the sun’s rays. It should be screened or put in a blackened box, or laid on black wool.

A good Photometer being still a desideratum, I had recourse to the old wedge of coloured glass, of an uniform neutral tint, the distance between whose extremes, or between transparency and total opacity, was one foot. A moveable arm carrying a brass plate with a slit and a vernier, enables the observer to read off at the vanishing point of the sun’s limb, to one five-hundredth of an inch. I generally took the mean of five readings as one, and the mean of five of these again I regarded as one observation; but I place little dependence upon the results. The causes of error are quite obvious. As far as the effects of the sun’s light on vegetation are concerned, I am inclined to think that it is of more importance to register the number of hours or rather of parts of each hour, that the sun shines, and its clearness during the time. To secure valuable results this should be done repeatedly, and the strength of the rays by the black-bulb thermometer registered at each hour. The few actinometer observations will be found in another part of the Appendix.

The dew-point has been calculated from the wet-bulb, by Dr. Apjohn’s formula, or, where the depression of the barometer is considerable, by that as modified by Colonel Boileau.[395] The saturation-point was obtained by dividing the tension at the dew-point by that at the ordinary temperature, and the weight of vapour, by Daniell’s formula.

[395] Journal of Asiatic Society, No. 147 (1844), p.135.

The following summary of meteorological observations is alluded to at vol. i., p. 15.

I.—_Table-land of Birbhoom and Behar, from Taldanga to Dunwah. Average elevation 1,135 feet._

It is evident from these observations, that compared with Calcutta, the dryness of the atmosphere is the most remarkable feature of this table-land, the temperature not being high; and to this, combined with the sterility of the soil over a great part of the surface, must be attributed the want of a vigorous vegetation. Though so favourably exposed to the influence of nocturnal radiation, the amount of the latter is small. The maximum depression of a thermometer laid on grass never exceeded 10°, and averaged 7°; whereas the average depression of the dew-point at the same hour amounted to 25° in the morning. Of course no dew was deposited even in the clearest star-light night.

February 1848 Hour Sunrise 9 a.m. 3 p.m. 9 p.m. TEMPERATURE Mean Max. Min. Range 56·6 65·2 46·3 18·9 70·1 77·0 61·2 15·8 75·5 81·7 65·2 16·5 61·7 66·2 55·5 10·7 WET-BULB Mean Max. Depression Min. Depression 48·2 12·5 6·0 53·7 19·3 14·3 55·3 22·5 16·7 49·3 20·5 9·0 Elasticity of Vapour ·276 ·264 ·248 ·248 DEW-POINT Mean Max. Min. Max. Depression Min. Depression 39·5 52·0 23·3 31·7 10·4 37·9 52·7 24·5 39·2 24·3 36·0 46·8 24·3 48·4 34·9 36·1 50·0 [396]9·1 56·9 16·2 Weight of Vapour in cubic feet 3·088 2·875 2·674 2·745 SATURATION Mean Max. Min. ·550 ·680 ·330 ·330 ·450 ·260 ·260 ·320 ·190 ·410 ·590 ·140 Number of observations 7 7 7 10

Extreme variations of temperature 35·4° Extreme variations of relative humidity ·540 Extreme diff. solar and nocturnal radiation 96·5°

[396] Taken during a violent N.W. dust-storm.

SOLAR RADIATION MORNING Hour Th. Black Bulb Diff. Phot. 9.30 a.m. 10 a.m. 10 a.m. 9 a.m. 9 a.m. 9 a.m. 77·0 69·5 77·0 63·5 61·2 67·0 130 124 137 94 106 114 53·0 54·5 60·0 30·5 44·8 47·0 -- 10·320 -- 10·230 -- 10·350 Mean 69·2 117·5 48·1 10·300

AFTERNOON Hour Th. Black Bulb Diff. Phot. 3.30 p.m. 3 p.m. 3 p.m. 3.30 p.m. 3 p.m. 81·7 80·5 81·5 72·7 72·5 109 120 127 105 110 27·3 39·5 45·5 32·3 37·5 -- 10·320 10·330 10·230 10·390 Mean 77·8 114·2 68·4 10·318

NOCTURNAL RADIATION SUNRISE Exposed thermometer On earth On grass Temperature Mean diff. from air Max. diff. from air Number of observations 51·1 4·0 9·0 6 48·3 2·5 3·7 3 46·6 6·2 9·0 5

NINE P.M. Exposed thermometer On earth On grass Temperature Mean diff. from air Max. diff. from air Number of observations 56·4 5·3 7·5 7 53·8 4·9 5·5 6 54·4 7·2 10·0 7

On one occasion, and that at night, the dew-point was as low as 11·5°, with a temperature of 66°, a depression rarely equalled at so low a temperature: this phenomenon was transient, and caused by the passage of a current of air loaded with dust, whose particles possibly absorbed the atmospheric humidity. From a comparison of the night and morning observations of thermometers laid on grass, the earth, and freely exposed, it appears that the grass parts with its heat much more rapidly than the earth, but that still the effect of radiation is slight, lowering its temperature but 2° below that of the freely exposed thermometer.

As compared with the climate of Calcutta, these hills present a remarkable contrast, considering their proximity in position and moderate elevation.

The difference of temperature between Calcutta and Birbhoom, deduced from the sunrise, morning and afternoon observations, amounts to 4°, which, if the mean height of the hills where crossed by the road, be called 1,135 feet, will be equal to a fall of one degree for every 288 feet.

In the dampness of its atmosphere, Calcutta contrasts very remarkably with these hills; the dew-point on the Hoogly averaging 51·3°, and on these hills 38°, the corresponding saturation-points being 0·559 and 0·380.

The difference between sunrise, forenoon and afternoon dew-points at Calcutta and on the hills, is 13·6° at each observation; but the atmosphere at Calcutta is relatively drier in the afternoon than that of the hills; the difference between the Calcutta sunrise and afternoon saturation-point being 0·449, and that between the hill sunrise and afternoon, 0·190. The march of the dew-point is thus the same in both instances, but owing to the much higher temperature of Calcutta, and the greatly increased tension of the vapour there, the relative humidity varies greatly during the day.

In other words, the atmosphere of Calcutta is loaded with moisture in the early morning of this season, and is relatively dry in the afternoon: in the hills again, it is scarcely more humid at sunrise than at 3 p.m. That this dryness of the hills is partly due to elevation, appears from the disproportionately moister state of the atmosphere below the Dunwah pass.

II.—_Abstract of the Meteorological observationsctaken in the Soane Valley (mean elevation 422 feet)._

The difference in mean temperature (partly owing to the sun’s more northerly declination) amounts to 2·5° of increase in the Soane valley, above that of the hills. The range of the thermometer from day to day was considerably greater on the hills (though fewer observations were there recorded): it amounted to 17·2° on the hills, and only 12·8° in the valley. The range from the maximum to the minimum of each day amounts to the same in both, above 20°. The extreme variations in temperature too coincide within 1·4°.

The hygrometric state of the atmosphere of the valley differs most decidedly from that of the hills. In the valley dew is constantly formed, which is owing to the amount of moisture in the air, for nocturnal radiation is more powerful on the hills. The sunrise and 9 p.m. observations in the valley, give a mean depression of the dew-point below the air of 12·3°, and those at the upper level of 21·2°, with no dew on the hills and a copious deposit in the valley. The corresponding state of the atmosphere as to saturation is 0·480 on the hills and 0·626 in the valley.

The vegetation of the Soane valley is exposed to a less extreme temperature than that of the hills; the difference between solar and nocturnal radiation amounting here only to 80·5°, and on the hills to 96·5°. There is no material difference in the power of the sun’s rays at the upper and lower levels, as expressed by the blackbulb thermometer, the average rise of which above one placed in the shade, amounted to 48° in both cases, and the maximum occurred about 11 a.m. The decrease of the power of the sun’s rays in the afternoon is much the most rapid in the valley, coinciding with a greater reduction of the elasticity of vapour and of humidity in the atmosphere.

The photometer observations show a greater degree of sun’s light on the hills than below, but there is not at either station a decided relation between the indications of this instrument and the black-bulb thermometer. From observations taken elsewhere, I am inclined to attribute the excess of solar light on the hills to their elevation; for at a far greater elevation I have met with much stronger solar light, in a very damp atmosphere, than I ever experienced in the drier plains of India. In a damp climate the greatest intensity may be expected in the forenoon, when the vapour is diffused near the earth’s surface; in the afternoon the lower strata of atmosphere are drier, but the vapour is condensed into clouds aloft which more effectually obstruct the sun’s rays. On the Birbhoom and Behar hills, where the amount of vapour is so small that the afternoon is but little drier than the forenoon, there is little difference between the solar light at each time. In the Soane valley again, where a great deal of humidity is removed from the earth’s surface and suspended aloft, the obstruction of the sun’s light is very marked.

DUNWAH TO SOANE RIVER, AND UP SOANE TO TURA

February 10–19th Hour Sunrise 9 a.m. 3 p.m. 9 p.m. TEMPERATURE Mean Max. Min. Range 57·6 62·0 53·5 8·5 74·0 81·0 63·5 17·5 77·6 87·5 71·0 16·5 64·5 68·7 60·0 8·7 WET-BULB Mean Max. Depression Min. Depression 51·7 8·5 3·8 59·5 18·5 4·0 59·9 26·0 6·8 55·5 12·5 2·5 Elasticity of Vapour 0·352 0·382 0·357 0·370 DEW-POINT Mean Max. Min. Max. Depression Min. Depression 46·1 53·6 40·6 16·9 7·0 48·5 56·7 38·0 33·5 6·8 46·4 60·0 36·0 44·2 11·0 47·5 55·6 41·0 24·1 4·4 Weight of Vapour in cubic feet 3·930 4·066 3·658 4·014 SATURATION Mean Max. Min. ·680 ·787 ·566 ·460 ·818 ·338 ·352 ·703 ·237 ·572 ·860 ·452 Number of observations 10 8 9 10

Extreme variations of temperature 34·0° Extreme variations of relative humidity ·623 Extreme diff. solar and nocturnal radiation 80·5°

NOCTURNAL RADIATION

SUNRISE Exposed thermometer On earth On grass Temperature Mean diff. from air Max. diff. from air Number of observations 53·2 4·5 8·5 9 54·0 3·7 9·0 9 51·5 6·2 7·5 8

NINE P.M. Exposed thermometer On earth On grass Temperature Mean diff. from air Max. diff. from air Number of observations 59·9 4·6 11·5 10 60·7 3·8 10·5 10 56·4 8·1 13·5 10

SOLAR RADIATION MORNING Time Th. Black Bulb Diff. Phot. 9 a.m. 11 a.m. 10.30 a.m. 10 a.m. 10 a.m. 10.30 a.m. 70·0 81·0 71·5 72·0 80·0 78·0 125 119 126 117 122 128 55·0 38·0 54·5 45·0 42·0 50·0 10·300 10·230 10·300 10·220 -- -- Mean 75·4 122·8 47·4 10·262

AFTERNOON Time Th. Black Bulb Diff. Phot. 4 p.m. 3 p.m. 3 p.m. 3 p.m. 76·5 80·0 76·0 87·5 90 105 102 126 13·5 25·0 26·0 38·5 -- 10·210 10·170 -- Mean 80·0 105·7 25·7 10·190

NOCTURNAL RADIATION FROM PLANTS
SUNRISE NINE P.M. Air
temperature 59·5 55·0 67·5 67·0 64·3
Calotropis -- 49·5 -- -- 58·5 Difference --
5·5 -- -- 5·83
Argemone 57·0 47·0 53·0 56·0 57·0 Difference
2·5 8·0 14·0 11·0 7·3

III.—_VALLEY OF SOANE RIVER, TURA TO SULKUN (Mean elev. 517 feet)_

February 20th to March 3rd Hour Sunrise 9 a.m. 3 p.m. 9 p.m. TEMPERATURE Mean Max. Min. Range 56·8 70·0 50·0 20·0 82·0 89·0 69·0 20·0 88·6 94·7 81·5 13·2 68·0 74·0 61·0 13·0 WET-BULB Mean Max. Depression Min. Depression 52·5 10·0 1·5 61·2 24·3 12·0 62·4 30·2 14·5 56·8 15·0 6·0 Elasticity of Vapour 0·380 0·385 0·289 0·369 DEW-POINT Mean Max. Min. Max. Depression Min. Depression 48·3 53·1 41·1 17·3 5·4 48·7 60·2 40·3 45·2 22·0 40·8 50·9 32·3 57·2 25·1 47·4 51·8 42·6 27·1 10·2 Weight of Vapour in cubic feet 4·240 4·097 2·975 3·933 SATURATION Mean Max. Min. ·754 ·831 ·570 ·342 ·488 ·226 ·211 ·598 ·154 ·511 ·703 ·415 Number of observations 12 11 11 11

Extreme variation of temperature 44·7° Extreme variation of relative humidity ·677 Extreme diff. solar and nocturnal radiation 100°

NOCTURNAL RADIATION

SUNRISE Exposed thermometer On earth On grass Temperature Mean diff. from air Max. diff. from air Number of observations 51·7 5·1 8·0 9 52·4 3·4 7·0 9 48·8 7·0 11·5 9

NINE P.M. Exposed thermometer On earth On grass Temperature Mean diff. from air Max. diff. from air Number of observations 61·2 6·8 10·5 10 64·3 4·6 8·5 9 55·8 11·8 17·0 9

SOLAR RADIATION MORNING Time Temp. Black Bulb Diff. Phot. 11.30 a.m. 10.30 a.m. Noon Noon Noon Noon 85·5 89·0 90·0 85·0 86·0 90·0 129 132 132 130 138 138 44·5 43·0 42·0 45·0 52·0 48·0 -- -- 10·140 -- -- -- Mean 87·6 133 45·8 10·140

AFTERNOON Time Temp. Black Bulb Diff. Phot. 3 p.m. -- -- -- -- 85·5 92·5 92·0 89·5 93·5 116 128 120 128 144 30·5 35·5 28·0 38·5 50·5 -- -- -- -- -- Mean 90·6 127 36·6 --

NOCTURNAL RADIATION FROM PLANTS SUNRISE Air temperature Barley Diff. Calo- tropis Diff. Arge- mone Diff. 61·0 57·0 57·0 58·5 57·0 50·0 50·5 56·0 56 46 52 52 52 45 43 -- 5·0 11·0 5·0 6·5 5·0 5·0 7·5 -- 56·5 48·0 -- -- -- 45·5 -- -- 4·5 9·0 -- -- -- 4·5 -- -- 57·0 50·0 50·0 -- -- -- -- 49·0 4·0 7·0 7·0 -- -- -- -- 7·0 55·9 49·4 6·4 50·0 6·0 51·5 6·2 NINE P.M. Air temperature Barley Diff. Calo- tropis Diff. Arge- mone Diff. 68·5 70·0 69·0 74·0 62·5 67·5 61·0 -- -- -- -- 51·5 67·5 50·0 -- -- -- -- 11·0 10·0 11·0 -- 65·0 57·0 59·0 -- 62·5 -- -- 5·0 12·0 15·0 -- 5·0 -- 56·0 67·0 57·0 -- -- -- -- 12·5 3·0 12·0 -- -- -- -- 67·5 56·3 10·7 60·9 9·3 60·0 9·2

The upper course of the Soane being in some places confined, and exposed to furious gusts from the gullies of the Kymore hills, and at others expanding into a broad and flat valley, presents many fluctuations of temperature. The mean temperature is much above that of the lower parts of the same valley (below Tura), the excess amounting to 5.4°. The nights and mornings are cooler, by 1·2°, the days hotter by 10°. There were also 10° increase of range during the thirteen days spent there; and the mean range from day to day was nearly as great as it was on the hills of Bengal.

There being much exposed rock, and the valley being swept by violent dust-storms, the atmosphere is drier, the mean saturation point being ·454, whereas in the lower part of the Soane’s course it was ·516.

A remarkable uniformity prevails in the depression of thermometers exposed to nocturnal radiation, whether laid on the earth, grass, or freely exposed; both the mean and maximum indication coincide very nearly with those of the lower Soane valley and of the hills. The temperature of tufts of green barley laid on the ground is one degree higher than that of short grass; _Argemone_ and _Calotropis_ leaves maintain a still warmer temperature; from the previous experiments the _ Argemone_ appeared to be considerably the cooler, which I was inclined to attribute to the smoother and more shining surface of its leaf, but from these there would seem to be no sensible difference between the radiating powers of the two plants.

IV.—_TABLE-LAND OF KYMORE HILLS (Mean elev. 979 feet)_

February 20th to March 3rd Hour Sunrise 9 a.m. 3 p.m. 9 p.m. TEMPERATURE Mean Max. Min. Range 65·3 69·0 57·5 11·5 81·6 83·5 79·5 4·0 88·1 90·0 84·5 5·5 71·1 76·0 68·0 8·0 WET-BULB Mean Max. Depression Min. Depression 57·7 8·0 6·0 65·3 19·0 14·0 63·3 26·5 21·5 60·3 13·0 8·3 Elasticity of Vapour 0·428 0·468 0·324 0·433 DEW-POINT Mean Max. Min. Max. Depression Min. Depression 52·0 55·5 45·9 14·1 11·6 54·5 57·9 49·0 33·0 12·9 43·7 47·8 37·9 46·6 42·2 52·3 56·7 46·8 21·9 13·8 Weight of Vapour in cubic feet 4·710 5·000 3·417 4·707 SATURATION Mean Max. Min. ·647 ·741 ·648 ·421 ·479 ·344 ·240 ·295 ·214 ·542 ·643 ·491 Number of observations 4 3 3 4

Extreme variation of temperature 32·5° Extreme variation of relative humidity ·527 Extreme diff. solar and nocturnal radiation 110·5°

NOCTURNAL RADIATION

SUNRISE Exposed thermometer On earth On grass Temperature Mean diff. from air Max. diff. from air Number of observations 59·5 3·5 3·5 2 56·0 1·5 1·5 1 54·7 8·2 8·5 2

NINE P.M. Exposed thermometer On earth On grass Temperature Mean diff. from air Max. diff. from air Number of observations 71·5 3·3 7·0 3 62·5 5·5 5·5 1 61·0 8·2 11·0 2

The rapid drying of the lower strata of the atmosphere during the day, as indicated by the great decrease in the tension of the vapour from 9 a.m. to 3 p.m., is the effect of the great violence of the north-west winds.

From the few days’ observations taken on the Kymore hills, the temperature of their flat tops appeared 5° higher than that of the Soane valley, which is 500 feet below their mean level. I can account for this anomaly only on the supposition that the thick bed of alluvium, freely exposed to the sun (not clothed with jungle), absorbs the sun’s rays and parts with its heat slowly. This is indicated by the increase of temperature being due to the night and morning observations, which are 3·1° and 8·5° higher here than below, whilst the 9 a.m. and 3 p.m. temperatures are half a degree lower.

The variations of temperature too are all much less in amount, as are those of the state of the atmosphere as to moisture, though the climate is rather damper.

On the subject of terrestrial radiation the paucity of the observations precludes my dwelling. Between 9 p.m. and sunrise the following morning I found the earth to have lost but 6·5° of heat, whereas a mean of nine observations at the same hours in the valley below indicated a loss of 12°.

Though the mean temperature deduced from the few days I spent on this part of the Kymore is so much above that of the upper Soane valley, which it bounds, I do not suppose that the whole hilly range partakes of this increase. When the alluvium does not cover the rock, as at Rotas and many other places, especially along the southern and eastern ridges of the ghats, the nights are considerably cooler than on the banks of the Soane; and at Rotas itself, which rises almost perpendicularly from the river, and is exposed to no such radiation of heat from a heated soil as Shahgunj is, I found the temperature considerably below that of Akbarpore on the Soane, which however is much sheltered by an amphitheatre of rocks.

V.—_Mirzapore on the Ganges._

During the few days spent at Mirzapore, I was surprised to find the temperature of the day cooler by nearly 4° than that of the hills above, or of the upper part of the Soane valley, while the nights on the other hand were decidedly warmer. The dew-point was even lower in proportion, 7·6°, and the climate consequently drier. The following is an abstract of the observations taken at Mr. Hamilton’s house on the banks of the Ganges (p. 363).

It is remarkable that nocturnal radiation as registered at sunrise is much more powerful at Mirzapore than on the more exposed Kymore plateau; the depression of the thermometer freely exposed being 3° greater, that laid on bare earth 6°, and that on the grass 1·4° greater, on the banks of the Ganges.

During my passage down the Ganges the rise of the dew-point was very steady, the maximum occurring at the lowest point on the river, Bhaugulpore, which, as compared with Mirzapore, showed an increase of 8° in temperature, and of 30·6° in the rise of the dew-point. The saturation-point at Mirzakore was ·331, and at the corresponding hours at Bhaugulpore ·742.

MIRZAPORE (Mean elev. 362 feet)

March 9th to 13th, 1848 Hour Sunrise 9 a.m. 3 p.m. 9 p.m. TEMPERATURE Mean Max. Min. Range 61·1 63·0 58·0 5·0 76·1 83·0 71·0 12·0 86·0 -- -- -- 76·0 -- -- -- WET-BULB Mean Max. Depression Min. Depression 48·8 51·5 47·0 58·5 56·5 51·7 61·7 24·3 -- 63·5 12·5 -- Elasticity of Vapour ·236 ·302 ·295 ·480 DEW-POINT Mean Max. Min. Max. Depression Min. Depression 34·3 39·7 29·7 32·8 23·8 41·9 -- -- 52·3 15·7 41·3 -- -- 44·7 -- 55·2 -- -- 20·8 -- Weight of Vapour in cubic feet 2·574 3·271 3·089 5·127 SATURATION Mean Max. Min. ·405 ·450 ·327 ·324 ·603 ·176 ·264 -- -- ·511 -- -- Number of observations 3 3 1 1

Air in shade Sunrise Exposed Therm. Diff. Exposed on earth Diff. Exposed on grass Diff. 60·0 62·5 63·0 58·0 55·0 54·5 55·5 53·0 5·0 8·0 7·5 5·0 -- 56·0 50·5 54·0 -- 6·5 12·5 4·0 52·0 52·5 50·5 50·0 8·0 10·0 12·5 8·0 60·9 54·6 6·4 53·5 7·7 51·3 9·6

B.

ON THE MINERAL CONSTITUENTS AND ALGÆ OF THE HOT-SPRINGS OF BEHAR, THE HIMALAYA, AND OTHER PARTS OF INDIA, ETC., INCLUDING NOTES ON THE FUNGI OF THE HIMALAYA.

(By Dr. R. D. Thomson and the Rev. M. J. Berkeley, M.A., F.L.S.)

The following remarks, for which I am indebted to the kindness of the able chemist and naturalist mentioned above, will be highly valued, both by those who are interested in the many curious physiological questions involved in the association of the most obscure forms of vegetable life with the remarkable phenomena of mineral springs; or in the exquisitely beautiful microscopic structure of the lower Algæ, which has thrown so much light upon a branch of natural history, whose domain, like that of astronomy, lies to a great extent beyond the reach of the unassisted eye.—J.D.H.

1. Mineral water, Soorujkoond, Behar (vol. i., p. 27), contains chloride of sodium and sulphate of soda.

2. Mineral water, hot springs, Yeumtong, altitude 11,730 feet (see vol. ii., p. 117). Disengages sulphuretted hydrogen when fresh.—This water was inodorous when the bottle was opened. The saline matter in solution was considerably less than in the Soorujkoond water, but like that consisted of chloride of sodium and sulphate of soda. Its alkaline character suggests the probability of its containing carbonate of soda, but none was detected. The rocks decomposed by the waters of the spring consist of granite impregnated with sulphate of alumina. It appears that in this case the sulphurous waters of Yeumtong became impregnated in the air with sulphuric acid, which decomposed the felspar,[397] and united with its alumina. I found traces only of potash in the salt.

[397] I have, in my journal, particularly alluded to the garnets (an aluminous mineral) being thus entirely decomposed.—J.D.H.

Sulphuretted hydrogen waters appear to give origin to sulphuric acid, when the water impregnated with the gas reaches the surface; and I have fine fibrous specimens of sulphate of lime accompanied with sulphur, from the hot springs of Pugha in west Tibet, brought by Dr. T. Thomson.

3. Mineral water, Momay hot springs, (vol. ii., p. 133).—When the bottle was uncorked, a strong smell of sulphuretted hydrogen was perceived. The water contains about twenty-five grains per imp. gallon, of chloride of sodium, sulphate and carbonate of soda; the reaction being strongly alkaline when the solution was concentrated.

4. Effloresced earth from Behar (vol. i., p. 13), consists of granite sand, mixed with sesquicarbonate of soda.

_On the Indian Algæ which occur principally in different parts of the Himalayan Range, in the hot-springs of Soorujkoond in Bengal, Pugha in Tibet, and Momay in Sikkim; and on the Fungi of the Himalayas._ By the Rev. M. J. Berkeley, M.A.

It is not my intention in the present appendix to give specific characters or even accurately determined specific names to the different objects within its scope, which have come under investigation, as collected by Dr. Hooker and Dr. Thomson. To do so would require far more time than I have at present been able to devote to the subject, for though every species has been examined microscopically, either by myself or Mr. Broome, and working sketches secured at the same time, the specific determination of fresh water Algæ from Herbarium specimens is a matter which requires a very long and accurate comparison of samples from every available locality, and in the case of such genera as _Zygnema, Tyndaridea,_ and _Conferva,_ is, after all, not a very satisfactory process.

The object in view is merely to give some general notion of the forms which presented themselves in the vast districts visited by the above-mentioned botanists, comprising localities of the greatest possible difference as regards both temperature and elevation; but more especially in the hot-springs which occur in two distant parts of the Himalayas and in Behar, and these again under very different degrees of elevation and of extrinsic temperature.

The Algæ from lower localities are but few in number, and some of these of very common forms. We have for instance from the Ganges, opposite Bijnour, a _ Batrachospermum_ and _Conferva crispata,_ the former purple below, with specimens of _Chantransia,_ exactly as they might occur in the Thames. The _Conferva,_ or more properly _ Cladophora,_ which occurs also under various forms, at higher elevations, as in the neighbourhood of Simla and Iskardo, swarms with little parasites, but of common or uninteresting species. In the Bijnour specimens, these consist of common forms of _Synedra, Meridion circulare,_ and a _Cymbella,_ on others from Dacca, there are about three species of _Synedra,_[398] a minute _Navicula_ and _Gomphonema curvatum._ Nothing, in fact, can well be more European. One splendid Alga, however, occurs at Fitcoree, in Behar, on the banks of nullahs, which are dry in hot weather, forming a purple fleece of coarse woolly hairs, which are singularly compressed, and of extreme beauty under the microscope, from the crystalline green of the articulated string which threads the bright red investing sheath. This curious Alga calls to mind in its colouring _Cænocoleus Smithii,_ figured in English Botany, t. 2940, but it has not the common sheath of that Alga, and is on a far larger scale. One or two other allied forms, or species, occur in East Nepal, to which I purpose giving, together with the Behar plant, the generic name of _Erythronema._ From the Soane River, also, is an interesting Alga, belonging to the curious genus _Thwaitesia,_ in which the division of the endochrome in the fertile cells into four distinct masses, sometimes entirely free, is beautifully marked. In some cases, indeed, instead of the ordinary spores, the whole moss is broken up into numerous bodies, as in the fertile joints of _Ulothrix,_ and probably, as in that case, the resultant corpuscles are endowed with active motion. In Silhet, again, is a magnificent _ Zygnema,_ allied to _Z. nitidum,_ with large oval spores, about 1/285 part of an inch long, and a dark golden brown colour, and containing a spiral green endochrome.

[398] Two of these appear to be _S. Vaucheriæ_ and _S. inæqualis._

Leaving, however, the lower parts of India, I shall first take the species which occur in Khasia, Sikkim, Eastern Nepal, and the adjoining parts of Tibet.

In the hot valleys of the Gtreat Rungeet, at an elevation of about 2000 feet, we have the _Erythronema,_ but under a slightly different form; at Nunklow, at about the same height; in Khasia, again, at twice that elevation; in Eastern Nepal, at 12,000; and, finally, at Momay, reaching up to 16,000 feet. In water, highly impregnated with oxide of iron, at 4000 feet in Sikkim, a _Leptothrix_ occurred in great abundance, coloured with the oxide, exactly as is the case with Algæ which grow in iron springs in Europe. At elevations between 5000 and 7000 feet, several European forms occur, consisting of _ Ulothrix, Zygnema, Oscillatoria, Lyngbya, Sphærozyga, Scytonema, Conferva,_ and _Cladophora._ The species may indeed not be identical with European species, but they are all more or less closely allied to well-known Hydrophytes. One very interesting form, however, either belonging to the genus _ Zygnema,_ or possibly constituting a distinct genus, occurs in streams at 5000 feet in Sikkim, consisting of highly gelatinous threads of the normal structure of the _Zygnema,_ but forming a reticulated mass. The threads adhere to each other laterally, containing only a single spiral endochrome, and the articulations are very long. Amongst the threads are mixed those of some species of _Tyndaridea._ There is also a curious _Hormosiphon,_ at a height of 7000 feet; forming anastomosing gelatinous masses. A fine new species of _Lyngbya_ extends up as high as 11,000 feet. At 13,000 feet occurs either some simple _Conferva_ or _Zygnema,_ it is doubtful which from the condition of the specimens; and at the same elevation, in the nearly dry bed of the stream which flows from the larger lake at Momay, amongst flat cakes, consisting of felspathic silt from the glaciers above, and the débris of Algæ, and abounding in Diatomaceæ, some threads of a _Zygnema._ At 17,000 feet, an _ Oscillatoria,_ attached or adherent to _Zannichellia_; and, finally, on the bare ground, at 18,000 feet, on the Donkia mountains, an obscure species of _Cænocoleus._ On the surface of the glaciers at Kinchinjhow, on silt, there is a curious _Palmella,_ apparently quite distinct from any European form.

Amongst the greater part of the Algæ, from 4000 feet to 18,000 feet, various Diatomaceæ occur, which will be best noticed in a tabular form, as follows; the specific name, within brackets, merely indicating the species to which they bear most resemblance:—

Himantidium (_Soleirolii_) Odontidium (_hiemale,_ forma minor) Epithemia, _n. sp._ Cymbella Navicula, _n. sp._ Tabillaria (_flocculosa_ Odontidium (_hiemale_) Himantidium Odontidium (_turgidulum_) Epithemia (_ocellata_) Fragillaria Odontidium (_turgidulum_) Dictyocha (_gracilis_) Odontidium (_hiemale_) 4000 to 7000 feet 5000 to 7000 feet 7000 feet — — 6000 to 7000 feet 11,000 feet 16,000 feet 17,000 feet — 18,000 feet — — — Sikkim Sikkim Sikkim Sikkim Sikkim Sikkim Sikkim Momay Momay Tibet Momay Momay Momay Kinchinjhow

We now turn to those portions of Tibet or the neighbouring regions, explored by Dr. Thomson and Captain Strachey. The principal feature in the Algology is the great prevalence of species of _Zygnema_ and _Tyndaridea,_ which occur under a variety of forms, sometimes with very thick gelatinous coats. In not a single instance, however, is there the slightest tendency to produce fructification. _Conferva crispata_ again, as mentioned above, occurs in several localities; and in one locality a beautiful unbranched _Conferva,_ with torulose articulations. At Iskardo, Dr. Thomson gathered a very gelatinous species of _Draparnaldia,_ or more properly, a _ Stygeoclonium,_ if we may judge from a little conglomeration of cells which appeared amongst the threads. A _Tetraspora_ in Piti, an obscure _Tolypothrix,_ and one or two _ Oscillatoriæ,_ remarkable for their interrupted mode of growth, complete the list of Algæ, with the exception of one, to be mentioned presently; as also of _Diatomaceæ,_ and of the species of _Nostoc_ and _Hormosiphon,_ which occurred in great profusion, and under several forms, sometimes attaining a very large size (several inches across), especially in the districts of Le and Piti, and where the soil or waters were impregnated with saline matters. It is well known that some species of _Nostoc_ form an article of food in China, and one was used for that purpose in a late Arctic expedition, as reported by Dr. Sutherland; but it does not seem that any use is made of them in Tibet, though probably all the large species would form tolerable articles of food, and certainly, from their chemical composition, prove very nutritious. One species is mentioned by Dr. Thomson as floating, without any attachment, in the shallow water of the pools scattered over the plains, on the Parang River, separated only by a ridge of mountains from Piti, broad and foliaceous, and scarcely different from the common _ Nostoc,_ which occurs in all parts of the globe. I must not, however, neglect to record a very singular new genus, in which the young threads have the characters of _Tyndaridea,_ but, after a time, little swellings occur on their sides, in which a distinct endochrome is formed, extending backwards into the parent endochrome, separated from it by a well defined membrane, and producing, either by repeated pullulation, a compound mass like that of _Calothrix,_ or simply giving rise to a forked thread. In the latter case, however, there is no external swelling, but a lateral endochrome is formed, which, as it grows, makes its way through an aperture, whose sides are regularly inflected. I have given to this curious production the name of _Cladozygia Thomsoni._

The whole of the above Algæ occurred at heights varying from 10,000 to 15,500 feet. As in the Southern Himalayan Algæ, the specimens were infested with many Diatomaceæ, amongst which the most conspicuous were various _Cymbellæ_ and _Epithemiæ._ The following is a list of the species observed.

Cymbella (_gastroides_). Cymbella (_gracilis_). Cymbella (_Ehrenbergii_) and three others. Odontidium (_hiemale_). Odontidium (_mesodon_). Odontidium _n. sp._ Epithemia _n. sp._ Synedra (_arcus_). Synedra (_tenuis_). Synedra (_æqualis_). Denticula (_obtusa_). Gomphonema (_abbreviatum_). Meridion circulare.

There is very little identity between this list and that before given from the Southern Himalayas, as is the case also with the other Algæ. Till the species, however, have been more completely studied, a very accurate comparison cannot be made.

In both instances the species which grow in hot springs have been reserved in order to make their comparison more easy. I shall begin in an inverse order, with those of the springs of Pugha in Tibet, which attain a temperature of 174°. Two _ Confervæ_ only occur in the specimens which have been preserved, viz., an _Oscillatoria_ allied to that which I have called _O. interrupta,_ and a true _Conferva_ extremely delicate with very long articulations, singularly swollen at the commissures. The _Diatomaceæ_ are:—

Odontidium (_hiemale_). Odontidium (_mesodon_). Odontidium _n. sp.,_ same as at Piti on _Conferva._ Denticula (_obtusa_). Navicula. Cymbella, three species. Epithemia.

Scarcely any one of these except the _Navicula_ is peculiar to the locality. A fragment apparently of some _ Closterium,_ the only one which I have met with in the collection, accompanies one of the specimens.

The hot springs of Momay, (temp. 110°) at 16,000 feet, produce a golden brown _Cænocoleus_ representing a small form of _C. cirrhosus,_ and a very delicate _ Sphærozyga,_ an _Anabaina,_ and _Tolypothrix_; and at 17,000 feet, a delicate green _Conferva_ with long even articulations. With the latter is an _Odontidium_ allied to, or identical with _O. turgidulum,_ and with the former a fine species of _Epithemia_ resembling in form, but not in marking, _E. Faba, E. (Zebra)_ a fine _Navicula,_ perhaps the same with _N. major_ and _Fragilaria (virescens)._[399] In mud from one of the Momay springs (_a_), I detected _Epithemia (Broomeii n.s.),_ and two small _Naviculæ,_ and in the spring (_c_) two species of _Epithemia_ somewhat like _E. Faba,_ but different from that mentioned above.

[399] Mr. Thomas Brightwell finds in a portion of the same specimen _Epithemia alpestris, Surirella splendida, S. linearis,_ Smith, _Pinnularia viridis,_ Smith, _Navicula (lanceolata)_ and _Himantidium (arcus)._

The hot springs of Soorujkoond, of the vegetation of which very numerous specimens have been preserved, are extremely poor in species. In the springs themselves and on their banks, at temperatures varying from 80° to 158°, at which point vegetation entirely ceases, a minute _Leptothrix_ abounds everywhere, varying a little in the regularity of the threads in different specimens, but scarcely presenting two species. Between 84° and 112° there is an imperfect _Zygnema_ with very long articulations, and where the green scum passes into brown, there is sometimes an _Oscillatoria,_ of a very minute stellate _Scytonema,_ probably in an imperfect state. _ Epithemia ocellata_ also contributes often to produce the tint. An _Anabaina_ occurs at a temperature of 125°, but the same species was found also in the stream from the springs where the water had become cold, as was also the case with the _ Zygnema._

The Diatomaceæ consisted of:—

Epithemia Broomeii, _n. s._ Epithemia thermalis, _n. sp._ Epithemia inæqualis, _n. sp._ Navicula Beharensis, _n. sp._

The vegetation in the three sets of springs was very different. As regards the _Confervæ,_ taking the word in its older sense, the species in the three are quite different, and even in respect of genera there is little identity, but amongst the _Diatomaceæ_ there is no striking difference, except in those of the Behar springs where three out of the four did not occur elsewhere. In the Pugha and Momay springs, the species were either identical with, or nearly allied to those found in neighbouring localities, where the water did not exceed the ordinary temperature. A longer examination will doubtless detect more numerous forms, but those which appear on a first examination are sure to give a pretty correct general notion of the vegetation. The species are certainly less numerous than I had expected, or than might be supposed from the vegetation of those European hot springs which have been most investigated.

In conclusion, I shall beg to add a few words on the Fungi of the Himalayas, so far as they have at present been investigated. As regards these there is a marked difference, as might be anticipated from the nature of the climates between those parts of Tibet investigated by Dr. Thomson, and the more southern regions. The fungi found by Dr. Thomson were but few in number, and for the most part of very ordinary forms, differing but little from the produce of an European wood. Some, however, grow to a very large size, as for instance, _Polyporus fomentarius_ on poplars near Iskardo, exceeding in dimensions anything which this species exhibits in Europe. A very fine _Æcidium_ also infests the fir trees (_Abies Smithiana_), a figure of which has been given in the “Gardeners’ Chronicle,” 1852, p. 627, under the name of _Æcidium Thomsoni._ This is allied to the Hexenbesen of the German forests, but is a finer species and quite distinct. _Polyporus oblectans, Geaster limbatus, Geaster mammosus, Erysiphe taurica,_ a _Boletus_ infested with _Sepedonium mycophilum, Scleroderma verrucosum,_ an _Æcidium,_ and a _Uromyces,_ both on _Mulgedium Tataricum,_ about half-a-dozen Agarics, one at an altitude of 16,000 feet above the Nubra river, a _Lycoperdon,_ and _ Morchella semilibera,_ which is eaten in Kashmir, and exported when dry to the plains of India, make up the list of fungi.

The region of Sikkim is perhaps the most productive in fleshy fungi of any in the world, both as regards numbers and species, and Eastern Nepal and Khasia yield also an abundant harvest. The forms are for the most part European, though the species are scarcely ever quite identical. The dimensions of many are truly gigantic, and many species afford abundant food to the natives. Mixed with European forms a few more decidedly tropical occur, and amongst those of East Nepal is a _Lentinus_ which has the curious property of staining every thing which touches it of a deep rhubarb yellow, and is not exceeded in magnificence by any tropical species. The _Polypori_ are often identical with those of Java, Ceylon, and the Philippine Isles, and the curious _Trichocoma paradoxum_ which was first found by Junghuhn in Java, and very recently by Dr. Harvey in Ceylon, occurs abundantly on the decayed trunks of laurels, as it does in South Carolina. The curious genus _Mitremyces_ also is scattered here and there, though not under the American form, but that which occurs in Java. Though _Hymenomycetes_ are so abundant, the _ Discomycetes_ and _Ascomycetes_ are comparatively rare, and very few species indeed of _Sphœria_ were gathered. One curious matter is, that amongst the very extensive collections which have been made there is scarcely a single new genus. The species moreover in Sikkim are quite different, except in the case of some more or less cosmopolite species from those of Eastern Nepal and Khasia: scarcely a single _Lactarius_ or _ Cortinarius_ for instance occurs in Sikkim, though there are several in Khasia. The genus _Boletus_ through the whole district assumes the most magnificent forms, which are generally very different from anything in Europe.

C.

ON THE SOILS OF SIKKIM.

There is little variety in the soil throughout Sikkim, and, as far as vegetation is concerned, it may be divided into vegetable mould and stiff clay—each, as they usually occur, remarkably characteristic in composition of such soils. Bog-earth is very rare, nor did I find peat at any elevation.

The clay is uniformly of great tenacity, and is, I believe, wholly due to the effect of the atmosphere on crumbling gneiss and other rocks. It makes excellent bricks, is tenacious, seldom friable, and sometimes accumulated in beds fourteen feet thick, although more generally only about two feet. In certain localities, beds or narrow seams of pure felspathic clay and layers of vegetable matter occur in it, probably wholly due to local causes. An analysis of that near Dorjiling gives about 30 per cent. of alumina, the rest being silica, and a fraction of oxide of iron. Lime is wholly unknown as a constituent of the soil, and only occasionally seen as a stalactitic deposit from a few springs.

A layer of vegetable earth almost invariably covers the clay to the depth of from three to twelve or fourteen inches. It is a very rich black mould, held in its position on the slopes of the hills by the dense vegetation, and accumulated on the banks of small streams to a depth at times of three and four feet. The following is an analysis of an average specimen of the surface-soil of Dorjiling, made for me by my friend C. J. Muller, Esq., of that place:—

_a._—DRY EARTH

Anhydrous Water 83·84 16·16 ———— 100·00

_b._—ANHYDROUS EARTH

Humic acid Humine Undecomposed vegetable matter Peroxide of iron and manganese Alumina Siliceous matter, insoluble in dilute hydrochloric acid Traces of soda and muriatic acid 3·89 4·61 20·98 7·05 8·95 54·52 -- ———— 100·00

_c._—Soluble in water, gr. 1·26 per cent., consisting of soda, muriatic acid, organic matter, and silica.

The soil from which this example was taken was twelve inches deep; it abounded to the eye in vegetable matter, and was siliceous to the touch. There were no traces of phosphates or of animal matter, and doubtful traces of lime and potash. The subsoil of clay gave only 5·7 per cent. of water, and 5·55 of organic matter. The above analysis was conducted during the rainy month of September, and the sample is an average one of the surface-soil at 6000 to 10,000 feet. There is, I think, little difference anywhere in the soils at this elevation, except where the rock is remarkably micaceous, or where veins of felspathic granite, by their decomposition, give rise to small beds of kaolin.

D. (Vol. i., p. 37)

AN AURORA SEEN FROM BAROON ON THE EAST BANK OF THE SOANE RIVER. Lat. 24° 52′ N.; Long. 84° 22′ E.; Alt. 345 feet.

The following appearances are as noted in my journal at the time. They so entirely resembled auroral beams, that I had no hesitation in pronouncing them at the time to be such. This opinion has, however, been dissented from by some meteorologists, who consider that certain facts connected with the geographical distribution of auroras (if I may use the term), are opposed to it. I am well aware of the force of these arguments, which I shall not attempt to controvert; but for the information of those who may be interested in the matter, I may remark, that I am very familiar with the Aurora borealis in the northern temperate zone, and during the Antarctic expedition was in the habit of recording in the log-book the appearance presented by the Aurora australis. The late Mr. Williams, Mr. Haddon, and Mr. Theobald, who were also witnesses of the appearances on this occasion, considered it a brilliant display of the aurora.

_Feb. 14th,_ 9 p.m.—Bax. Corr. 29·751; temp. 62°; D.P. 41·0°; calm, sky clear; moon three-quarters full, and bright.

Observed about thirty lancet beams rising in the north-west from a low luminous arch, whose extremes bore W. 20° S., and N. 50° E.; altitude of upper limb of arch 20°, of the lower 8°. The beams crossed the zenith, and converged towards S. 15° E. The extremity of the largest was forked, and extended to 25° above the horizon in the S.E. by S. quarter. The extremity of the centre one bore S. 50° E., and was 45° above the horizon. The western beams approached nearest the southern horizon. All the beams moved and flashed slowly, occasionally splitting and forking, fading and brightening; they were brightly defined, though the milky way and zodiacal light could not be discerned, and the stars and planets, though clearly discernible, were very pale.

At 10 p.m., the luminous appearance was more diffused; upper limb of the arch less defined; no beams crossed the zenith; but occasionally beams appeared there and faded away.

Between 10 and 11, the beams continued to move and replace one another, as usual in auroras, but disappeared from the south-east quarter, and became broader in the northern hemisphere; the longest beams were near the north and north-east horizon.

At half-past 10, a dark belt, 4° broad, appeared in the luminous arch, bearing from N. 55° W. to N. 10° W.; its upper limb was 10° above the horizon: it then gradually dilated, and thus appeared to break up the arch. This appeared to be the commencement of the dispersion of the phenomenon.

At 10.50 p.m. the dark band had increased so much in breadth that the arch was broken up in the north-west, and no beams appeared there. Eighteen linear beams rose from the eastern part of the arch, and bore from north to N. 20° E.

Towards 11 p.m., the dark band appeared to have replaced the luminous arch; the beams were all but gone, a few fragments appearing in the N.E. A southerly wind sprang up, and a diffused light extended along the horizon.

At midnight, I saw two faint beams to the north-east, and two well defined parallel ones in the south-west.

E.

PHYSICAL GEOGRAPHY OF THE SIKKIM HIMALAYA, EAST NEPAL, AND ADJACENT PROVINCES OF TIBET.

Sikkim is included in a section of the Himalaya, about sixty miles broad from east to west, where it is bounded respectively by the mountain states of Bhotan and Nepal. Its southern limits are easily defined, for the mountains rise abruptly from the plains of Bengal, as spurs of 6000 to 10,000 feet high, densely clothed with forest to their summits. The northern and north-eastern frontier of Sikkim is beyond the region of much rain, and is not a natural, but a political line, drawn between that country and Tibet. Sikkim lies nearly due north of Calcutta, and only four hundred miles from the Bay of Bengal; its latitude being 26° 40′ to 28° N., and longitude 88° to 89° E.

The main features of Sikkim are Kinchinjunga, the loftiest hitherto measured mountain, which lies to its north-west, and rises 28,178 feet above the level of the sea; and the Teesta river, which flows throughout the length of the country, and has a course of upwards of ninety miles in a straight line. Almost all the sources of the Teesta are included in Sikkim; and except some comparatively insignificant streams draining the outermost ranges, there are no rivers in this country but itself and its feeders, which occupy the largest of the Himalayan valleys between the Tambur in East Nepal, and the Machoo in Western Bhotan.

An immense spur, sixty miles long, stretches south from Kinchin to the plains of India; it is called Singalelah, and separates Sikkim from East Nepal; the waters from its west flank flow into the Tambur, and those from the east into the Great Rungeet, a feeder of the Teesta. Between these two latter rivers is a second spur from Kinchinjunga, terminating in Tendong.