From the number of volcanoes both active and dormant in the Archipelago, the seismic foci are numerous, and, while there are some islands where earthquakes are infrequent, the major portion has been frequently visited with disturbances more or less serious. A map of seismic foci published by the Observatory of Manila, under the direction of the Jesuit fathers, gives ten different centers of earthquake activity, most of which bear an intimate geographical relation to the more prominent volcanoes of the Archipelago. They extend from the northern part of Luzón to the southern part of Mindanao.

Without entering upon any description of the different earthquakes that have been felt in the more remote parts of the Archipelago, many of which were local in their manifestations, nor attempting to give a list of all the disturbances that have been recorded for any one region, mention will be made of those which have been felt in recent times at Manila, and which for the most part are attributed to the focus of the Taal Volcano. Between the years 1870 and 1897, a period of twenty-seven years, this region has to its credit 157 earthquakes, of which 34 were merely perceptible, 95 were slight, 15 were moderately violent, and 13 were severe. The most violent was experienced in the month of July, 1880, when the Provinces of Manila (now Rizal), Cavite, Laguna, Bulucán, Pampanga, Nueva Ecija, Pangasinán, and certain districts of Príncipe, La Infanta, and Morong were the theater of one of the most violent and destructive earthquakes recorded in the annals of seismic disturb

ances in the Archipelago. Within the extensive zone formed by the provinces named the shocks were so violent that they either destroyed stone buildings or so injured them that they had to undergo important repairs.

The effects of this earthquake were visited not alone upon buildings, as the inhabitants of San Carlos in Pangasinán saw their rice fields destroyed, and at Cavite columns of what appeared to be ashes and water arose in the bay in front of the town, and gave off a decided sulphurous odor. In Nueva Ecija there were extensive subsidences of land which caused extensive inundations. In the district of Infanta large rocks were loosened from the eastern side of the mountains, and in all the provinces. named large crevasses opened in the ground, chiefly in the neighborhood of the rivers, the deltas, and upon the seashore.

All authorities agree to-day in the direct and immediate connection between earthquakes and volcanic phenomena; and that eruptions are due to steam tension. It is therefore of capital importance to know the chemical composition of the matter ejected by volcanic vents, as this gives an approximate idea of the amount of pressure or tension to which the steam is subjected before it can be relieved by escaping through some vent in the earth's crust. It is well known that acid lavas, such as rhyolites, have a much higher melting point than basic lavas, and therefore those volcanoes which eject acid lavas generally originate vibratory waves. of greater force than those ejecting basic lavas. It will be noted that in the list of volcanoes given, the rocks of all Philippine volcanoes are trachyte, basalt, or andesite, indicating that, comparatively speaking, the internal pressure will find vent more easily or with less resistance and consequently with less serious disturbances than were they of other composition.

Chapter III.

MINERAL RESOURCES.

[Revised by F. A. Thanisch.]

Difference between lignite and coal-Lignite a valuable mineral-Distribution of lignite-Assays of Philippine lignite-History of coal mining-Distribution of gold-Prospectors and miners at work-Methods employed-Gold fieldsIgorrote quartz mining-Placer mining-Platinum associated with gold— Copper-Native copper workings - Composition of copper ores Galena ores Magnetite Metal work- Petroleum Sulphur- Marble - Mineral waters-Mining legislation.

True (Paleozoic) coal does not exist, so far as known, in Malaysia. The nearest approach to it is the black, pitchy lignite similar to that of the State of Washington. The difference between lignite and true coal consists mainly in the quantity of combined water, which not only diminishes the percentage of combustible material but requires the expenditure of combustible constituents to convert it into steam or dissociated gases of the temperature of the flame. The black lignite is, perhaps, judging from our present knowledge of the mineral resources of the Archipelago, the most valuable mineral asset of the Philippines, and is widely distributed from southern Luzón southward. It is difficult to trace its distribution in detail, because there are also brown lignites of less value at many points, while the available reports are for the most part not sufficiently explicit to determine which fuel has been discovered.

The black lignite is probably of Eocene age, and is very similar to the Bornean or Javanese lignites, particularly to the fuel of Labuan, in North Borneo, well known throughout the Far East. The brown lignites of the Philippines probably correspond, both geologically and in quality, to the late Tertiary lignites of Borneo. The Japanese "coal" is also a lignite, and no better than the black fuel of the Philippines, which will serve admirably for all local purposes, and in case of need will answer for war vessels as well. Its heating power is approximately from two-thirds to three-fourths that of the best Paleozoic steam coals, such as the Cardiff.

Coal seams have been discovered and recorded in many localities in the Philippines. In the Island of Luzón concessions have been granted only in the extreme southeastern corner, in the Province of Albay, but Centeno

states that applications have been made for concessions in Tayabas, although no development work has been done. In the following localities in Luzón fossil fuel has been found: In Cagayan there is an outcropping at a bayou called Calbong; in Abra lignite is found on the River Malanas, in the township of Dolores; in Unión it occurs at Aringay; in the Province of Rizal there is lignite at Tatauiran Gulch and other points; in Camarines Sur lignite is found near Pasacao, on the southwestern coast, and also on the Caramuan Peninsula, which forms the eastern extremity of the province. The localities mentioned seem to lie at the edge of a field which stretches southward into Sámar and which is extremely promising. About 12 or 15 miles to the south of Catanduanes lie the small islands of Carraray, Batan, and Rapurapu. Here the lignite is black, resembling bituminous coal in appearance, and is of excellent quality. It is found in seams of good thickness and is close to tidewater.

The Batan coal appears to crop out at Gatbó, not far from Bacón, in the Province of Sorsogón. Among the seams is one from 4 to 8 meters in width which has been tried on steamers and found to be satisfactory. In the southeastern part of Negros coal seams occur lying 6 or 8 miles from the coast and in a line substantially parallel thereto. Cebú divides with Albay and Sorsogon the reputation of being the most important coal region of the Archipelago, and has been carefully examined by Mr. Abella. The coal occurs chiefly on the eastern slope of the central range between Dávao and Boljoón. The principal deposits are in the townships of Dávao, Compostela, and Naga. In 1899 the Compostela mines were being worked in a small way and coasting steamers depended upon them for their supply of fuel.

The existence of coal has been known to the natives for an indefinite period, and a mountain in the Naga district bears the name Úling, which is the Visayan name for coal. The Spaniards became aware of the coal deposits in 1827, but never worked any of the mines with energy or method.

While coal occurs in almost every township along the eastern coast of Cebú, Mr. Abella properly protests against speaking of the region as a coal basin. The strata are sharply flexed, folded, and faulted, the coal seams sometimes standing vertically, which makes careful investigation necessary before plans are entered upon to mine on an extensive scale. On the other hand, labor being cheap and the distance to the seacoast being but a few miles, the Cebú coal should be able to compete with Japanese or Australian coal in the Manila market and render a handsome profit. The seams are often 4 feet in thickness, and one at Compostela is over 8 feet. Tests of these coals have been made on Spanish war vessels and under boilers at the arsenal at Cavite with satisfactory results. The following tables show analyses of Philippine, Japanese, and Australian

coal and give a good idea of the comparative merits of the different classes:

TABLE I.-Coal analyses, Bureau of Government Laboratories, 1902–3.

TABLE II.—Coal analyses from the Coal Measures of the Philippines, 1901.

But little is known of the coal of Leyte, Mindanao, and the adjacent islands beyond the fact of the existence of certain deposits which have been located. While it seems reasonable to class all Visayan coals as Eocene, because of their composition and the stratigraphical relations in Cebú and Negros, the same assumption is not justified in Mindanao because of lack of knowledge. It would be in no way surprising, however, to find the coals of eastern Mindanao similar to those of Leyte, which is clearly a continuation of the Surigao Peninsula.

,

The past history of coal mining by the Spaniards is a long record of ignorance, avarice, and mistakes. They attempted to mine coal as though it were a precious metal, and indeed it became equivalent to it in some instances when measured by the cost of production. At one time the government was so impressed with the value of this industry that it was for a while a monopoly in which the government was interested, but as a business venture it was not a success. On the whole, the coal deposits of the Archipelago offer opportunities for investment which may well invite