The northern islands of the archipelago lie in the region of the typhoon, and have three seasons,—the cold, the hot, and the wet. The first extends from November to February or March, when the atmosphere is bracing rather than cold. The hot season lasts from March to June, and the heat becomes very oppressive before the beginning of the southerly monsoon. Thunder-storms of terrific violence occur during May and June. The wet season begins with heavy rains, known by the natives as “collas,” and until the end of October the downpour is excessive. “Earthquakes are sufficiently frequent and violent in the Philippines to affect the style adopted in the erection of buildings; in 1874, for instance, they were very numerous throughout the archipelago, and in Manila and the adjacent provinces shocks were felt daily for several weeks. The most violent earthquakes on record in the Philippines occurred in July, 1880, when the destruction of property was immense, both in the capital and in other important towns of central Luzon.” Though situated in the equatorial region, the elevations of the mountains give a range of climate that allows the production of a great variety of valuable crops. Tobacco, sugar, hemp, and rice are the chief staples produced. The swamps and rivers are infested with crocodiles, and the dense woods with monkeys and serpents of many species. Rich deposits of gold are known to exist, but have been little developed. To quote from the _Revue des Deux Mondes_ of Paris: In the same district are found Indians, Negritos, Manthras, Malays, Bicols, half-breed Indians and Spaniards, Tagalas, Visayas, Sulus, and other tribes. The Negritos (little negroes) are real negroes, blacker than a great many of their African conquerors, with woolly hair growing in isolated tufts. They are very diminutive, rarely attaining four feet nine inches in height, and with small, retreating skulls. This race forms a branch equal in importance to the Papuan. It is believed to be the first race inhabiting the Philippines, but, as well as everywhere else, except in the Andaman Islands, it has been more or less absorbed by the stronger races, and the result in the archipelago has been the formation of several tribes of half-breeds numbering considerably more than half a million. Side by side with them, and equally poor and wretched, are the Manthras, a cross between the Negritos and Malays and the degenerate descendants of the Saletes, a warlike tribe conquered by the Malayan Rajah Permicuri in 1411. Then come the Malay Sulus, all Mohammedans and still governed by their Sultan and their _datos_, feudal lords who, under the suzerainty of the Spaniards, have possessed considerable power.