The islands are chiefly of volcanic origin and their surface is much broken by hills, isolated volcanoes and mountain ranges running north and south, northwest and southeast or northeast and southwest. There are twelve active volcanoes in the group and eight others with well-defined cones that are either dormant or extinct. The highest elevation in the islands is Mount Apo, an extinct volcano on Mindanao, 10,312 feet, with Mount Mayon, an active volcano on Luzon, next, 8970 feet. Earthquakes are frequent and occasionally violent. The most important of the group are Mindanao, Luzon, Samar, Palawan, Panay, Negros, Leyte, Mindoro, Cebú, Masbate and Bohol. The coast line, which is over 11,000 miles in length, is fringed with coral reefs and indented by many gulfs and bays. There are plenty of good natural harbors, the principal one being Manila in Luzon, which affords perfect shelter for shipping, even in the severest storms. Next in importance are the harbors of Iloilo and Cebú. Climatic conditions vary widely. However, it may be said in a general way that the climate is characterized by a uniformly high temperature, excessive humidity, heavy rainfall and violent tropical storms. Near the seacoast, it is moderate between November and the first of March. The latter part of March and the months of July, August and September are warm and very hot weather comes in April, May and June. The nights, however, are always cool. The temperature naturally changes as the elevation above the sea increases, but at ordinary levels it averages 77 degrees Fahrenheit in January, and 83 degrees in May. The annual rainfall is about 74 inches, and two-thirds of this comes in July, August, September and October. Of course the precipitation in certain localities is affected by mountain ranges that cause condensation from moisture-laden trade winds. In the lowlands that are not protected by mountains, the rainfall is regular. Typhoons occur between April and October, but they are not nearly so severe as the hurricanes that visit the West Indies and Mauritius. In October, 1882, a typhoon did a great deal of damage in Manila, and there was a serious loss of life in the great storm that visited Samar and Leyte in 1897. The well-appointed observatory in Manila sends out warnings of the approach of typhoons and much life and property are saved by this means. The soil is generally reddish-brown in color and is largely made up of disintegrated lava with an admixture of decayed vegetable matter; sometimes decomposed coral limestone is present. [Illustration: PLOUGHING FIELD BEFORE PLANTING CANE, PHILIPPINES] [Illustration: PLOUGHING AT LA CARLOTA, OCCIDENTAL NEGROS, PHILIPPINES]