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In BHl.'j, however, the. extraordinary constancy and strength of the northeast winds during December were duenot so much to the invasion of the high-pressure area of the north as to the extended and stationary depressionsin the southern parts of the Archipelago. An area of low- pressure, whose center occupied the region betweenthe ninth and eleventh parallels of north latitude, persisted during the greater part of the month. At Manilathe barometer oscillated nearly always within the limits for “variable weather;” in the north of the island,though it reached the height proper to the “northers,” it nevertheless rose considerably less than is usual forthis month. More still, the days of the most violent northers were precisely those characterized by the lowestbarometer readings throughout the Archipelago, since it was the depression in the south which accentuated thegradient and induced the currents from the north. This ell'ect, which might he called peculiar to the cyclonescrossing these seas in lower parallels, gave to the last December a unique character, not only on account of thegreat extension but also of the almost complete immovability of said southern depression.

These were the two circumstances which contributed to the great constancy in direction and the long durationof the northeast winds experienced this year. Both would have been impossible if the depression had developedinto a real storm. For, whenever during these months a cyclone, regular in form and movement, passes throughthe south of the Archipelago, the aerial currents from the first quadrant cease on account of the wind’s veeringtoward east, and the sky clears in the central and western regions of the Archipelago when the disturbance hascrossed the meridian of Manila, and enters the China Sea.

From what has been said it is easily concluded how great an influence such widely extended depressionsin the south exercise on the state of the weather in the Island of Luzon. In the region of minimum pressure—that is, in the islands of the Visayas and in the north of Mindanao—calm weather generally prevailed, but therains were so torrential as to cause not a few disastrous accidents, lienee it is clear that the region of strongwinds lay in the north and northeast of the exterior zones of the depression, where the gradient was probablysteeper, while the rain area penetrated to the very center thereof. More to the south reigned the weak atmos-pheric currents of the second quadrant, in consequence whereof, as we have been informed, the eastern coasts ofMindanao were much more navigable than in other years in which the northeast monsoon attained less force inthe neighborhood of Luzon.

Conditions similar to those just described as prevailing during the month of December of lDOIl,may .be considered as peculiar to the winter season in the Archipelago. During the last twomonths, January and February, the second factor is less frequent, because the southern depressionsare rarer. It is noteworthy that in many instances, -when the northers are due principally tosouthern depressions, the pressure is low also in the neighborhood of Formosa, the area of relativelyhigh pressure extending only over northern Luzon. In this case the northers blow only in thevicinity of the Archipelago. Among the areas of low pressure crossing the southern islands therearc some which develop into real typhoons, causing at times great destruction and making naviga-tion in the southern seas dangerous during this season.

To this summary description of the character and causes of the northern monsoon rainfallwe will add a few Words about its amount and distribution throughout the Archipelago. Therelative amount, as has been stated before, reaches 50 per cent of the annual quantity only invery few of the easternmost stations; hence, this rainfall does not constitute the principal rainyseason in any considerable part of the Archipelago. The absolute amount ranges between 1,871.3millimeters in the eastern stations of Samar and 58 millimeters in the west of Luzon. Theamount also depends greatly on the topographical position; that is, whether the station is on theeastern or on the western coast, and whether it is surrounded bv mountains or lias a free horizontoward north and northeast. This last circumstance makes the distribution of the winter rainsmuch more irregular than that of the summer rains. The driest regions are those on tire coastsof Luzon west of the Caraballos and Zambales mountains; a fact easily understood if we rememberthat even in the eastern regions the most insignificant hills suffice to modify the rainfall. It isalso frequently observed on the eastern coasts that when the northers are not rather strong, therainy zone on land is very narrow, although there may be no appreciable obstacle.