Page:Physical Geography of the Sea and its Meteorology.djvu/457

Rh years' experience at sea, I have never seen a typhoon or hurricane so severe. Lost two men overboard—saved one. Stove skylight, broke my barometer, etc., etc." Severe gales in this part of the Atlantic—i. e., on the polar side of the calm belt of Cancer—rarely occur during the months of June, July, August, and September. This appears to be the time when the fiends of the storm are most busily at work in the "West Indies. During the remainder of the year, these extra-tropical gales, for the most part, come from the north-west. But the winter is the most famous season for these gales. That is the time when the Gulf Stream has brought the heat of summer and placed it (§ 172) in closest proximity to the extremest cold of the north. And there should, therefore, it would seem, be a conflict between these extremes; consequently, great disturbances in the air, and a violent rush from the cold to the warm. In like manner, the gales that most prevail in the extra-tropics of the southern hemisphere come from the pole and the west, i. e., south-west.

808. Storm and Rain alerts.—Storm and Rain Charts for the Atlantic Ocean have already been published by the Observatory, and others for the other oceans are in process of construction. The object of such charts is to show the directions and relative frequency of calms, fogs, rain, thunder, and lightning. These charts are very instructive. They show that that half of the atmospherical coating of the earth which covers the northern hemisphere—if we may take as a type of the whole what occurs on either side of the equator in the Atlantic Ocean—is in a much less stable condition than that which covers the southern.

CHAPTER. XX. § 811-542. — THE WINDS OF THE SOUTHERN HEMISPHERE.

811. Repetition often necessary.—A work of this sort, which is progressive, must necessarily bear with it more or less of repetition. It embodies the results of the most extensive system of philosophical observations, physical investigation, and friendly co-operation that has ever been set on foot. As facts are developed, theories are invented or expanded to reconcile them. As soon as this is done, or in a short time thereafter, some one or more of