Such has been the train of thought suggested to the mind of the writer of this article, by an examination of the nature and physical relations of COLOR. This property of matter might appear to a superficial observer as one of inferior importance. He would admit that the differences of color add to the happiness of the human race, inasmuch as they give variety and beauty to material objects, and afford one of the most easy methods of distinguishing them from each other, but would probably deny that the existence of animal life is at all dependant upon color, and that it is essential to the present constitution of things. But let such an one reflect a little more upon this property--let him consider attentively all its relations--and he will doubtless change his opinion. In travelling from the equator toward the poles, we cannot but be struck with the fact, that there exists a difference of color corresponding to a change of climate. Under the equator, the covering of the earth, that is, the vegetation, is darker than in any other part of the globe; and, as there is but little change of climate through the year, this dark covering does not give place either to the light tints of autumn, or to the snowy robe of winter. In advancing north, the foliage becomes lighter in proportion to the increase of latitude. In the temperate zone, the dark, rich robe of the tropics gives place to one of livelier hue, which, after covering the earth during a part of the year, assumes the light colors of decay, and is buried beneath the snow. Thus this change continues to keep pace with the diminution of temperature, till we enter the frigid zone, and reach the region of eternal frost. From this difference of color in the north and south, and in summer and winter, we may deduce this general fact, that the earth adapts itself in color to the variations of temperature, presenting a dark surface to the heat of summer and the tropics, and a light one to the cold of winter and the frigid zone.