Some entertain the following opinion: The earth is porous at many points, possessing not merely those first shafts which it received as ventilators at its creation, but many subsequently opened up by various changes. In some places water has washed away the soil that was on the surface; part has been eaten away by torrents, while parts have been exposed by the disruptive action of great tides. Through the interstices thus produced air enters. If it so happen now that the sea has shut it in and driven it deeper, and the waves prevent its escape by the same road, egress and regress being alike closed, the air rolls about within the earth. Its natural tendency is to hurry straight forward, but as that path is closed, it presses upward and lashes the earth, whose weight lies heavy upon it. XVI I must further mention a view held by the majority of writers, which 1 probably I shall myself support. The earth does not lack air within; that everybody knows. I do not mean merely the air which holds it together and unites its parts, which exists even in stones and dead bodies; but I mean that fresh vital air which supports all life. Unless the earth possessed this store of air, how could she infuse it into so many trees and crops, which derive their life from this and no other source? How could she nourish all the different roots that sink into 2 the soil in one place and another, some merely attached to the surface, others sunk deeper, had she not an abundant supply of the breath of life, which produces so many varied growths and rears them with its nourishing draught? These are the slighter arguments that I hitherto urge. Why, all the heaven we see, which is shut in by fiery ether, the highest portion of the universe, all these stars, whose number cannot be conceived, all this concourse of heavenly bodies, and, to mention only one more, this sun, that urges his course so close to us, many times larger than the whole circuit of the earth--all these draw their nourishment from materials of earth which they share among them, and are sustained, of course, by nothing else than the breath of the 3 earth. This is their nourishment, this their pasturage. Now the earth would be unable to nourish so many bodies of such size, larger even than itself, unless it were full of breath, which it exhales from every part of it day and night. For there must be a large reserve of that from which so much is sought and taken; in fact, the supply to be drawn from it is created for the occasion. The earth would not possess a 4 perennial supply of air sufficient for the wants of so many heavenly bodies, unless the elements issued and returned alternately and were transmutable into one another. But apart from this, it is necessary that the earth be abundantly filled with it, and be able to draw it forth from her hidden store. There is no doubt then that a great quantity of air lurks in the interstices of the earth, and a widely