Whatever of importance is accomplished in those countries where climate has overpowered a race is best and principally done by the men of the temperate zones, who carry with them perseverance, courage, and ability, and maintain their ascendency, true to their type, while they have their life to live. But with our own eyes we may perceive how much climate affects agriculture. The humidity or dryness of soils, their natural or acquired heat or cold, the prevailing winds, the quantity of rain, the snows, the dews, all affect the planter of the seed and the tiller of the ground; they increase or diminish the aggregate of the products of countries, the value of their imports and exports,--in short, their material power, their resources, their influence, their very existence. The climate of our own country is exceedingly variable. The transitions from heat to cold are very sudden, the range of the mercury is very great. In the North, we have almost the Arctic winters; in the South, almost the peculiarities of the tropics. Of the State of Pennsylvania it has been said, that in this respect it is a compound of all the countries in the world. Mr. Jefferson and Dr. Rush, as before observed, insisted that our climate has changed; and Williams, the historian of Vermont, contends that New England has deteriorated in its seasons, temperature, harvests, and health, since its early settlement. Our winds blow from every point of the compass, but a due north wind is very rare. Our great western lakes have a large influence on our climate. Some learned men have asserted, that, if they were land, their area being about ninety-four thousand square miles, the region would be so cold as to be scarcely inhabitable. Such is an outline of our subject. The science itself is by no means systematized. Many things are taken for granted which may yet be disproved. If, says Humboldt, we perceive a want of connection in the phenomena of certain sciences, we may anticipate the revelation of new facts, whose importance will probably be commensurate with the attention directed to other branches of study. What we want is a larger class of observers, and not only those who are professional persons, but those who would commune with Nature, and seek to invigorate their minds by the acquisition of new ideas, and a recourse to rich and pure sources of enjoyment. But more than this. It is a requirement of the present age, says the same authority, that there should be an equal appreciation of all branches of mathematical and physical science; for the material wealth and the growing prosperity of nations are principally based upon a more enlightened employment of the products and forces of Nature.