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made to produce as much as many acres formerly did. Taking one year with another, the amount of vegetable productions is just sufficient for the sustenance of the animals. Supply and demand are in as rigid proportions here as elsewhere. Nature is no doubt as admirably endowed with the regulating principles for the conservation of quantities, as we know she is with those for the conservation of areas. If from the combustion of coal, and the consumption of food, there be a greater quantity of gases evolved and discharged into the air, there is on the other hand an increased vegetable production sufficient to absorb and condense it. The stream is not enlarged, its current only is quickened, Like the water in the pipes through which our cities are supplied: the population of the city and the consumption of water may have doubled or trebled, yet the quantity in the pipes is a constant—the stream through is only more rapid, but the volume is the same; so with these gases through the atmosphere.
Which way so ever we turn, we see the most exquisite display of wisdom and harmony, symmetry and beauty, every where preserved between cosmical arrangements and terrestrial adaptations. Following up the clue which, by the achievements of science, has been placed in our hands, we might go on and trace out the beneficent designs with which wisdom assigned the proportions between the water and the dry land, the sandy deserts and the fruitful plains. The Potomac river, the St. Lawrence, the great lakes, and all those waters which run down to the sea, are again taken up by this downy atmosphere, and carried back to the mountains. Imagine the rivers of only this continent—the Mississippi and the Amazon among them—running back in constant streams through the air to their sources in the
