Here are likewise found various species of earths which might be applied to valuable purposes, as painters' colours, and otherwise. The most common are the yellow and red, probably ochres, and the white, which answers the description of the milenum of the ancients.
VOLCANOES.
There are a number of volcano mountains in this, as in almost all the other islands of the eastern Archipelago. They are called in the Malay language gunong-api, or more correctly, gunong ber-api. Lava has been seen to flow from a considerable one near Priamang; but I have never heard of its causing any other damage than the burning of woods. This however may be owing to the thinness of population, which does not render it necessary for the inhabitants to settle in a situation that exposes them to danger of this kind. The only volcano I had an opportunity of observing opened in the side of a mountain, about twenty miles inland of Bencoolen, one-fourth way from its top, as nearly as I can judge. It scarcely ever failed to emit smoke; but the column was only visible for two or three hours in the morning, seldom rising and preserving its form, above the upper edge of the hill, which is not of a conical shape but extending with a gradual slope.
EARTHQUAKES.
The high trees with which the country thereabout is covered, prevent the crater from being discernible at a distance; and this proves that the spot is not considerably raised or otherwise affected by the earthquakes which are very frequently felt there. Sometimes it has emitted smoke upon these occasions, and in other instances not. Yet during a smart earthquake which happened a few years before my arrival it was remarked to send forth flame, which it is rarely known to do.* The apprehension of the European inhabitants however is rather more excited when it continues any length of time without a tendency to an eruption, as they conceive it to be the vent by which the inflammable matter escapes that would otherwise produce these commotions of the earth. Comparatively with the descriptions I have read of earthquakes in South America, Calabria, and other countries, those which happen in Sumatra are generally very slight; and the usual manner of building renders them but little formidable to the natives.
(*Footnote. Some gentlemen who deny the fact of its having at any time emitted flame, conjecture that what exhibits the appearance of smoke is more probably vapour arising from a considerable hot spring. The natives speak of it as a volcano.)
REMARKABLE EFFECTS OF AN EARTHQUAKE.
The most severe that I have known was chiefly experienced in the district of Manna in the year 1770. A village was destroyed by the houses falling down and taking fire, and several lives were lost.* The ground was in one place rent a quarter of a mile, the width of two fathoms, and depth of four or five. A bituminous matter is described to have swelled over the sides of the cavity, and the earth for a long time after the shocks was observed to contract and dilate alternately. Many parts of the hills far inland could be distinguished to have given way, and a consequence of this was that during three weeks Manna River was so much impregnated with particles of clay that the natives could not bathe in it. At this time was formed near to the mouth of Padang Guchi, a neighbouring river south of the former, a large plain, seven miles long and half a mile broad; where there had been before only a narrow beach. The quantity of earth brought down on this occasion was so considerable that the hill upon which the English resident's house stands appears, from indubitable marks, less elevated by fifteen feet than it was before the event.
(*Footnote. I am informed that in 1763 an entire village was swallowed up by an earthquake in Pulo Nias, one of the islands which lie off the western coast of Sumatra. In July or August of the same year a severe one was felt in Bengal.)
Earthquakes have been remarked by some to happen usually upon sudden changes of weather, and particularly after violent heats; but I do not vouch this upon my own experience, which has been pretty ample. They are preceded by a low rumbling noise like distant thunder. The domestic cattle and fowls are sensible of the preternatural motion, and seem much alarmed; the latter making the cry they are wont to do on the approach of birds of prey. Houses situated on a low sandy soil are least affected, and those which stand on distinct hills suffer most from the shocks because the further removed from the centre of motion the greater the agitation; and the loose contexture of the one foundation, making less resistance than the solidity of the other, subjects the building to less violence. Ships at anchor in the road, though several miles distant from the shore, are strongly sensible of the concussion.