Page:Physical Geography of the Sea and its Meteorology.djvu/119

 Rh Architect, the mind is enriched with the conviction that it has comprehended a thought that was entertained at the creation. For this reason the beautiful compensations which philosophers have discovered in terrestrial arrangements are sources of never-failing wonder and delight. How often have we been called on to admire the benign provision by which fresh water is so constituted that it expands from a certain temperature down to freezing! We recognize in the formation of ice on the top instead of at the bottom of freezing water, an arrangement which subserves, in manifold ways, wise and beneficent purposes. So, too, when we discern in the upper sky (§ 234) currents of wind arranged in strata one above the other, and running hither and thither in different directions, may we not say that we can here recognize also at least one of the fore-ordained offices of these upper winds? That by sending down fresh air and taking up foul, they assist in maintaining the world in that state in which it was made and for which it is designed—"a habitation fit for man?"

241. The effect of downward currents in producing cold.—The phenomena of cold and warm "spells" are often observed in the United States, and I suppose in other parts of the world also; and here in these downward currents we have the explanation and the cause of sudden and severe local changes in the weather. These belts often lie east and west rather than north and south, and we frequently have much colder or hotter weather in them than we have even several degrees to the north or to the south of them. The conditions required for one of these cold "snaps" in America appear to be a north or north-west wind of considerable breadth from west to east. As it goes to the south, its tendency is, if it reach high enough, to bring down cold air from above in the manner of the trade-winds (§ 238); and when the air thus brought down chances to be, as it often is, dry and cold, we have the phenomenon of a cold belt, with warmer weather both to the north and the south of it. While I write the thermometer is—4° in Mississippi, lat. 32°, and they are having colder weather there than we have either in Washington or Cincinnati, 7° farther to the north.

242. The winter northers of Texas.—The winter "northers" of Texas sometimes bring down the cold air there with terrific effect. These bitter cold winds are very severe at Nueces, in the coast country, or the south-west corner of Texas bordering