One of the first things which must strike everybody is, that even in the temperate zone some countries are far more ravaged by thunderstorms than others. For instance, France suffers more than any other part of Europe, and England the least. We may probably find at least two causes which modify the development of thunderstorms. In the first place, the geographical position of the country relative to the great seasonal areas of high and low pressure. From this point of view we can readily see that France is far more exposed to the influence of small secondaries, which come in from the Atlantic, and which die out before they reach central Europe, than any other portion of that continent. In Great Britain, though the bulk of winter rain is cyclonic, a great deal of summer rainfall is non-isobaric; in Continental Europe a still larger proportion is of the latter character; so are most tropical rains, except the downpour of hurricanes; while the whole of the heavy rain on the equator, and all that falls in the doldrums, is also absolutely non-isobaric. A moderate whirlwind may be two hundred feet high, and not above ten feet in diameter. The dimensions, however, are very variable, for a whirlwind may vary in intensity from a harmless eddy in a dusty road to the destructive tornado of the United States. But by far the most striking non-isobaric rain in the world is the burst of the southwest monsoon in the Indian Ocean. The quality of the rain, if nothing else, distinguishes the monsoon from cyclonic precipitation. The rain in front of a Bengal cyclone seems to grow out of the air, while that of the monsoon falls in thunderstorms and from heavy cumulo-form clouds. The only rational suggestion which has been made to account for this burst of rain would look to a sudden inrush of damp air from the region of the doldrums as the source of the change in weather, but not of the direction of the wind, or of the shape of the isobars; for the burst is apparently almost coincident with the disappearance of the belt of high pressure to the south of the Bay of Bengal. The word “pampero” is, unfortunately, used in a very vague manner in the Argentine Republic and neighboring states. Every southwest wind which blows from off the pampas is sometimes called a pampero; and there is a still further confusion caused by calling certain dry dust-storms _pamperos sucios_, or dry pamperos. The true pampero may be described as a southwest wind, ushered in by a sudden short squall, usually accompanied by rain and thunder, with a very peculiar form of cloud-wreath.