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CLIMATE OF NORTH AMERICA.

That the sea-breeze rises over the land, and is carriedaway in the upper current which flows in an oppo-site direction, all admit. And that the action ofthe north-easters are, in many cases, similar tothat of the sea-breeze, I have every reason tobelieve. I entertain, however, views differentfrom those of Professor Mitchell as to the man-ner in which the upper current descends and thelower ascends. I consider that it is highly impor-tant that the exact modus operandi should be under-stood, as the same principle of action applies tothe north-easters, and a modification of it to thewinds in other storms.

In the case of the sea-breeze, the wind thatblows over the land does not rise in a column intothe upper current at the particular spot where thebreeze terminates; but as it gradually dies awayas it reaches the interior, it clearly shows that it isas gradually absorbed into the upper current overthe entire distance that it traverses. Thus, letthe side figure represent the sea-breeze on the eastcoast of Scotland :—

The breeze as it touches the land is strongest—say twenty miles an hour; then it lessens to fifteen,then to ten, and, last of all, there exist a calm at acertain distance from the shore. The breeze neverreaches this spot; for it is absorbed into the uppercurrent betwixt A and B. The sun heats andexpands the air as soon as it touches the land ;anfi thus it rises until it is rubbed off by thecurrent that prevails above. This principle of agradual rising is the only one by w'hich the gradualdiminution of the sea-breeze, as it travels towardsthe interior, can be explained. In like manner,the air descends from above over the sea in thesame gradual way. There is no focal area towhich the wind rushes and rises in a body; forthe focal area may be considered to extend as faras the breeze extends. It is quite clear that if the

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