Masonry arches were henceforth banished from the churches; the heavy walls of the latter were further strengthened by massive buttresses; and the towers were given truly enormous substructures. But even with these precautions there is at present hardly one out of the hundreds of churches built during the seventeenth and eighteenth centuries which did not some time or other require important repairs of its masonry work or even partial reconstruction owing to earthquake damages. The only structure of this class which thus far has withstood all convulsions, is the church of St. Agustin, Manila. Nevertheless, as we have stated before, the chroniclers hardly mention all this destruction, except in a very general and cursory manner. I do not hesitate to say: they were accustomed to see similar havoc created nearly every year in one part of the Archipelago or the other by some severe typhoon, accompanied by far greater loss of lives and property, and consequently much more felt by the people than the destruction of a church, convento, municipal building ("tribunal"), one or two bridges, or other masonry structure.

In the present catalogue our aim has been to present all that is known of the various violent and destructive earthquakes on record. The first column of each page contains the ordinal number of the disturbance for purposes of reference. In the second, the date is given as accurately as it could be ascertained, Roman numerals being used to designate the months. Unfortunately, of some earthquakes only the year is known; of others, the year and month. Of one (No. 32) the approximate hour has been recorded, but not the day of the month; while of another (No. 38) the hour has been preserved for posterity, but whether the phenomenon occurred during February or March, the records leave undecided. In the third column will be found, in the first place, the intensity of the disturbance, Roman numerals representing the degrees of the scale of De Rossi-Forel (I-X); then the region affected most, and finally the damages caused, if known, and other information, if available.

In describing the epicentral regions, the present distribution of the Archipelago into provinces has been used throughout the catalogue. This division is shown on the first of the two maps of the Philippines which accompany this catalogue (Plate I). As to the designation "Benguet" occasionally occurring in the text where provinces are enumerated, but not found on the map, we beg to offer the excuse that the region thus named is exceedingly well known in the Philippines as it contains Baguio, the health resort of the Islands. For the readers outside of the Archipelago we remark that Benguet is at present a subprovince of the Mountain Province, of which it forms the southernmost part. The location of Baguio is shown on the map on Plate II. A similar remark applies to Lepanto and Bontoc, likewise divisions of the Mountain Province, whose capitals, Cervantes and Bontoc, are indicated on the same map.

As we would hardly be justified in assuming that every reader is in possession of a detailed map of the Philippines, and a knowledge of the general distribution and the main directions of the principal mountain systems of an earthquake country is important, we add a second map on which these data are shown by means of dashes, together with the most important seismic regions, and the positions of the principal towns, bays, etc., mentioned in the text. (Plate II.)

Near the left margin of this second map will be found an index of the seismic regions just mentioned, each of them being represented by its ordinal number (large Roman figures). Near each of these ordinals is placed the corresponding number of earthquakes since 1862 contained in the catalogue (Arabic figures), which is followed, in brackets, by an analysis of the said number, in which Roman figures designate the degrees of the earthquake, scale of De Rossi-Forel, while small Arabic figures, written like