caves bring to the North Borneo Government a yearly rental of $9,000. One of the vaults in the caves is estimated to be nine hundred feet high. An idea of their population may be got from the statement that a steady column of the swifts (Callocalia) inhabiting them has been timed by the watch to fly for three quarters of an hour from one of the apertures. Passing Bod Lagit—"which means the hill to the skies, a legend recording that it formerly reached to the heavens, but, owing to the wickedness of its inhabitants, had subsided to its present height of four hundred feet"—and a hill of limestone called Chuko Besar, which contains some small caves and yields a few hundred bird's-nests each year, the explorers visited one of the owners of the Batu Timbang caves, of which two native rajahs share the proceeds in alternate years. They are situated on the river Quamute, a branch of the Kinabatangare, and are difficult of access on account of rapids. Some of the bird's-nests are of the best white description, but the larger proportion are gray and mixed with feathers. Still further up—three hours' climb from the Melikop branch, and eighteen hundred and ten feet above the sea-level—are the Obang-Obang limestone caves, which had not hitherto been visited by Europeans. The first cave reached after a three hours' climb, the last half-hour of it over slippery, moss-grown, limestone bowlders, is the most valuable, but can be approached only by experts in climbing. The entrance is a small hole, four feet by four feet, and is closed by a wooden grating so as to attract attention to the spot, as otherwise the unwary traveler might suddenly be precipitated to the depths below. Every two months this doorway is opened, and the climbers let themselves down into the caves by means of rattans, and gather all nests, large and small. This makes six seasons per annum. The same periods are observed in the collections at the Senobang caves in the Ulu Penungah. "The seasons at Gomanton, Batu Timbang, Madai, and Segalong number two or three during the twelve months, and these are too few, according to the Tungara tribe. They maintain that, by collecting them frequently—say six times per annum—they procure white nests in first-rate order, though some of these nests are young and but half formed, and that the Sulu traders give them a higher price in consequence. I noticed a great scarcity in swifts and a great preponderance of bats, which might be attributed to the too frequent collection of nests, which prevents the swifts from breeding. The Obang-Obang Mountain runs north and south, and is half a mile in length. There are seven entrances to the vaults from the top of the range, all situated close to each other. Five of these vaults do not contain any bird's-nests, there being no swifts, only bats dwelling there." The only chamber that can be entered by any one who is not an adept at climbing on rattans to
