The history of Sumatra

by William Marsden

No country in the world is better supplied with water than the western coast of the island. Springs are found wherever they are sought for, and the rivers are innumerable; but they are in general too small and rapid for the purpose of navigation. The vicinity of the mountains to that side of the island occasions this profusion of rivulets, and at the same time the imperfections that attend them, by not allowing them space to accumulate to any considerable size. On the eastern coast the distance of the range of hills not only affords a larger scope for the course of the rivers before they disembogue, presents a greater surface for the receptacle of rain and vapours, and enables them to unite a greater number of subsidiary streams, but also renders the flux more steady and uniform by the extent of level space than where the torrent rolls more immediately from the mountains. But it is not to be understood that on the western side there are no large rivers. Kataun, Indrapura, Tabuyong, and Sinkel have a claim to that title, although inferior in size to Palembang, Jambi, Indragiri, and Siak. The latter derive also a material advantage from the shelter given to them by the peninsula of Malacca, and Borneo, Banca, and the other islands of the Archipelago, which, breaking the force of the sea, prevent the surf from forming those bars that choke the entrance of the south-western rivers, and render them impracticable to boats of any considerable draught of water. These labour too under this additional inconvenience that scarcely any except the largest run out to sea in a direct course. The continual action of the surf, more powerful than the ordinary force of the stream, throws up at their mouths a bank of sand, which in many instances has the effect of diverting their course to a direction parallel with the shore, between the cliffs and the beach, until the accumulated waters at length force their way wherever there is found the weakest resistance. In the southerly monsoon, when the surfs are usually highest, and the streams, from the dryness of the weather, least rapid, this parallel course is of the greatest extent; and Moco-moco River takes a course, at times, of two or three miles in this manner, before it mixes with the sea; but as the rivers swell with the rain they gradually remove obstructions and recover their natural channel.

AIR.

The heat of the air is by no means so intense as might be expected in a country occupying the middle of the torrid zone. It is more temperate than in many regions without the tropics, the thermometer, at the most sultry hour, which is about two in the afternoon, generally fluctuating between 82 and 85 degrees. I do not recollect to have ever seen it higher than 86 in the shade, at Fort Marlborough; although at Natal, in latitude 34 minutes north, it is not unfrequently at 87 and 88 degrees. At sunrise it is usually as low as 70; the sensation of cold however is much greater than this would seem to indicate, as it occasions shivering and a chattering of the teeth; doubtless from the greater relaxation of the body and openness of the pores in that climate; for the same temperature in England would be esteemed a considerable degree of warmth. These observations on the state of the air apply only to the districts near the sea-coast, where, from their comparatively low situation, and the greater compression of the atmosphere, the sun's rays operate more powerfully. Inland, as the country ascends, the degree of heat decreases rapidly, insomuch that beyond the first range of hills the inhabitants find it expedient to light fires in the morning, and continue them till the day is advanced, for the purpose of warming themselves; a practice unknown in the other parts of the island; and in the journal of Lieutenant Dare's expedition it appears that during one night's halt on the summit of a mountain, in the rainy season, he lost several of his party from the severity of the weather, whilst the thermometer was not lower than 40 degrees. To the cold also they attribute the backwardness in growth of the coconut-tree, which is sometimes twenty or thirty years in coming to perfection, and often fails to produce fruit. Situations are uniformly colder in proportion to their height above the level of the sea, unless where local circumstances, such as the neighbourhood of sandy plains, contribute to produce a contrary effect; but in Sumatra the coolness of the air is promoted by the quality of the soil, which is clayey, and the constant and strong verdure that prevails, which, by absorbing the sun's rays, prevents the effect of their reflection. The circumstance of the island being so narrow contributes also to its general temperateness, as wind directly or recently from the sea is seldom possessed of any violent degree of heat, usually acquired in passing over large tracts of land in the tropical climates. Frost, snow, and hail I believe to be unknown to the inhabitants. The hill-people in the country of Lampong speak indeed of a peculiar kind of rain that falls there, which some have supposed to be what we call sleet; but the fact is not sufficiently established. The atmosphere is in common more cloudy than in Europe, which is sensibly perceived from the infrequency of clear starlight nights. This may proceed from the greater rarefaction of the air occasioning the clouds to descend lower and become more opaque, or merely from the stronger heat exhaling from the land and sea a thicker and more plentiful vapour. The fog, called kabut by the natives, which is observed to rise every morning among the distant hills, is dense to a surprising degree; the extremities of it, even when near at hand, being perfectly defined; and it seldom is observed to disperse till about three hours after sunrise.

WATERSPOUT.

That extraordinary phenomenon, the waterspout, so well known to and described by navigators, frequently makes its appearance in these parts, and occasionally on shore. I had seen many at sea; but the largest and most distinct (from its proximity) that I had an opportunity of observing, presented itself to me whilst on horseback. I was so near to it that I could perceive what appeared to be an inward gyration, distinct from the volume surrounding it or body of the tube; but am aware that this might have been a deception of sight, and that it was the exterior part which actually revolved--as quiescent bodies seem to persons in quick motion, to recede in a contrary direction. Like other waterspouts it was sometimes perpendicular and sometimes curved, like the pipe of a still-head, its course tending in a direction from Bencoolen Bay across the peninsula on which the English settlement stands; but before it reached the sea on the other side it diminished by degrees, as if from want of the supplies that should be furnished by its proper element, and collected itself into the cloud from which it depended, without any consequent fall of water or destructive effect. The whole operation we may presume to be of the nature of a whirlwind, and the violent ebullition in that part of the sea to which the lower extremity of the tube points to be a corresponding effect to the agitation of the leaves or sand on shore, which in some instances are raised to a vast height; but in the formation of the waterspout the rotatory motion of the wind acts not only upon the surface of the land or sea, but also upon the overhanging cloud, and seems to draw it downwards.

THUNDER AND LIGHTNING.

Thunder and lightning are there so very frequent as scarcely to attract the attention of persons long resident in the country. During the north-west monsoon the explosions are extremely violent; the forked lightning shoots in all directions, and the whole sky seems on fire, whilst the ground is agitated in a degree little inferior to the motion of a slight earthquake. In the south-east monsoon the lightning is more constant, but the coruscations are less fierce or bright, and the thunder is scarcely audible. It would seem that the consequences of these awful meteors are not so fatal there as in Europe, few instances occurring of lives being lost or buildings destroyed by the explosions, although electrical conductors have never been employed. Perhaps the paucity of inhabitants in proportion to the extent of country and the unsubstantial materials of the houses may contribute to this observation. I have seen some trees, however, that have been shattered in Sumatra by the action of lightning.*

(*Footnote. Since the above was written accounts have been received that a magazine at Fort Marlborough, containing four hundred barrels of powder, was fired by lightning and blown up on the 18th of March 1782.)

MONSOONS.

The causes which produce a successive variety of seasons in the parts of the earth without the tropics, having no relation or respect to the region of the torrid zone, a different order takes place there, and the year is distinguished into two divisions, usually called the rainy and dry monsoons or seasons, from the weather peculiar to each. In the several parts of India these monsoons are governed by various particular laws in regard to the time of their commencement, period of duration, circumstances attending their change, and direction of the prevailing wind according to the nature and situation of the lands and coasts where their influence is felt. The farther peninsula of India, where the kingdom of Siam lies, experiences at the same time the effects of opposite seasons; the western side, in the Bay of Bengal, being exposed for half the year to continual rains, whilst on the eastern side the finest weather is enjoyed; and so on the different coasts of Indostan the monsoons exert their influence alternately; the one remaining serene and undisturbed whilst the other is agitated by storms. Along the coast of Coromandel the change, or breaking up of the monsoon as it is called, is frequently attended with the most violent gales of wind.