In recent years petroleum, long known to the natives, has added much to the wealth of Java. The thrifty Hollander studied well-drilling in Pennsylvania and California; then he put his training to work on the Javanese oil-fields. As a result Java is beginning to supply not only the East Indies, but also Japan with coal-oil. Years ago travellers used to tell marvellous stories about a certain poison valley of Java in the centre of which stood an upas-tree. The tree itself was famed for the deadly effects of its poisonous exhalations, which killed man, beast, or bird that came near it. These stories proved to be mere fabrications. They grew out of the fact that near by was a valley from which arose at times carbonic-acid gas in sufficient quantity to kill small animals running over certain low places. But the upas played no part, though the juice of the tree is poisonous. Batavia is the capital of the Dutch East Indies. It is on low, flat land, half a dozen miles from the artificial harbor which has not long been finished; for the old port had but little protection from stormy seas and high winds. The swampy land on which the city is built has been drained by canals. Excepting the business streets, the city is almost hidden by the gardens with their profusion of plants. It is the Amsterdam of the Old World; and one will find as good wares in Batavia as in Holland. During the eruption of Krakatoa, Batavia was buried deep in dust and ragged cinders of lava. More than twenty thousand dead were under the heaps of ash. Surabaya is larger than Batavia and has a population of more than one hundred and fifty thousand. But Surabaya has not much trade with Europe; its commerce is mainly with the ports of Asia. The harbor is good and it has become the chief naval station of the Dutch East Indies. The Dutch authorities do not encourage visitors to Java. All visitors must have passports or permits; and if one goes to the interior, officials question him at every turn and demand his permit at every district. CHAPTER XXXIII THE DUTCH EAST INDIES--SUMATRA AND CELEBES Two lofty mountain ranges with a deep valley between them lie at the eastern side of the Indian Ocean. The Malay Peninsula is one range; the island of Sumatra is the other. The floor of the valley between them is covered by the sea and forms the Strait of Malacca. As islands go, Sumatra is of goodly size--larger than New York, Pennsylvania, and the New England States together. From end to end its length is about the distance between Boston and Chicago. Greenland, Borneo, New Guinea, and Madagascar are each larger. The equator crosses Sumatra at its central part.