Some of the caves in which edible birds’-nests are found are very large. At the entrance the visitor is met by thousands of bats and swallows. The latter resemble the common swallow in appearance, but are only half as large. These small swallows make the edible nests. Inside, the cave is often like an immense amphitheatre roofed like a dome, the middle of which is over a thousand feet high. Thousands of nests are seen clinging to the pillar-like rocky sides and roof. The most flimsy-looking stages of bamboos tied together with cane are the simple means employed by the natives to collect the nests from the seemingly most inaccessible positions. Though there are rifts in the sides through which come rays of light, still in parts the cave is so dark that lamps and torches have to be used. The Dyaks climb up the bamboo scaffolding, carrying with them long cane ladders. These are fixed against the sides. Two men work on each ladder, which often hangs high up in the air. One carries a light four-pronged spear about fifteen feet long, and near the prongs a lighted candle is fixed. Holding on to the ladder with one hand, he manages the spear with the other, and transfixes the nest. A slight push detaches it from the rock, and the spear is then held within reach of the second man, who detaches the nest and puts it into a basket tied to his waist. The natives say that there are two species of swallows that inhabit these caves. Those that take up their abode near the entrance of the cave build nests which are of no value. These birds often attack the other and smaller species which make the edible nests. The natives often destroy the nests of the larger swallows, so as to lessen their number. The best quality nests are very translucent, and of a pale yellow colour, and mixed with very few feathers. These are nests that have been freshly made. If the nests are not removed, the birds make use of them again, so that by age and accession of dirt they become quite useless. The old nests are of no value, and the natives destroy them, so that the birds may build new ones in their place. The nests are collected four times a year. The natives say that the birds will lay four times a year if their nests are collected often, but if there are only two collections, then the birds only lay twice in the year. The best time for collecting nests is when the eggs are just laid. One would imagine that there would be a danger of over-collecting, and that the number of birds would diminish; but the natives say there is no danger of this, as the birds carry on their breeding in nooks and crannies inaccessible to the collectors. Another jungle industry is the hunting for camphor. The kind the Dyaks obtain is known as “hard camphor,” and is found in crystals in the hollow trunk of a tree. It is much more valuable than ordinary camphor.