This spirited and indefatigable order of men, who, both by precept and example, encouraged agriculture, not only as the source of national greatness, but as preparatory to, and inseparable from, conversion to Christianity, which they well knew did not consist alone in ceremonies, but in fulfilling the duties of citizens and men, and who, whatever were their political sins, certainly possessed more than any other the talent of converting men from savage to civilized life, have left in the Phillippines some striking monuments of their wide-spreading and well-directed influence. Extensive convents (the ground stories of which were magazines), in the centre of fertile districts formerly in the highest state of cultivation, but now more than half abandoned,--tunnels,--canals,--reservoirs and dams, by which extensive tracts were irrigated for the purposes of cultivation, attest the spirit with which they encouraged this science; and if their expulsion was a political necessity, it certainly appears to have been in this country a moral evil. The restraints imposed on commerce were another insuperable bar to their prosperity, as depriving them of a market for their produce. Since foreigners have been allowed free intercourse with them, their agriculture has in some degree improved by the increased demand of produce; but under the present system, but little can be expected from it. [80] The soil is in general a rich red mould, with a great proportion of iron, and in some districts volcanic matters; it is easily worked and very productive: that in the immediate vicinity of Manila, and for four or five miles round it, extending to that distance from the coast of the Bay, is an alluvial soil, formed by the confluence of the numerous rivers with the ocean; it is stiff, and in all respects very inferior to the other. In some parts are extensive tracts, the reservoirs of the waters from the mountains in the rainy season, which first yield an amazing supply of fish, [81] and then a good crop of rice or pasture for the buffaloes. The frequent rains, and the numerous rivers and streams with which the country is every-where intersected, adds to its extraordinary fertility: it is seldom, if ever, afflicted with droughts, but is at times devastated by locusts (perhaps once in 10 or 15 years), and these make dreadful havoc amongst the canes. Their attacks, however, are partial, and generally take place after the rice is harvested, in December, disappearing before the rains. In 1818, nearly the whole of the canes were destroyed by them, and the Ayuntamiento of Manila expended from 60 to 80,000 dollars in purchasing large quantities of them, which were thrown into the sea. [82]