On the 16th of January, 1818, in Florida, near Mobile bay, a fire ball bursted with a considerable report. Immediately before the explosion, it was observed to project a cone of fire from each pole horizontally and at right angles with its course. Its bursting like a bomb-shell, indicated that it must have been hollow; and the two cones of light which appeared, beside its train, showed that it was open at the poles. Turn your attention to the general economy of nature throughout her works, and you will perceive in various and almost innumerable substances that she forms hollow cylinders or spheres in the room of solid ones. Enquire of the botanist, and he will tell you that the plants which spring up spontaneously, agreeable to the established laws of nature, are hollow cylinders. If a hollow globe would answer the ends of supporting organic life as well as a solid one――why not be hollow, as well as a stalk of wheat? or by what laws is the stalk of wheat governed, that it should _always_ grow hollow? What law in nature causes the quills and feathers of a bird to be hollow cylinders? Why are they not solid? I presume it is for this plain reason, that nature, throughout all her works, has wisely assigned to every thing just matter enough for strength and usefulness; and has in no case overburthened it with unnecessary and cumbrous weight. Enquire of the anatomist, and he will tell you that the large bones of all animals are hollow, and particularly that the bones of birds are more than ordinarily so: even the minutest hairs of our heads are hollow. Go to the mineralist, and he will inform you that the stone called Ærolites, and many other mineral bodies, are composed of hollow concentric circles; and, that strata of different kinds abound in various mineral substances. Even the earth itself is composed, as geologists tell us, of various strata, composed of different substances, and varying from one degree of density to another. If every part of our globe be regulated according to the received laws of gravity, and the relative density of matter, why do we find almost all over the world, light alluvial soil in the vallies and plains; and on the tops of the highest mountains, the more heavy granite, and some of the heaviest substances that nature knows? We can hardly indulge the thought that all this is the work of volcanic eruptions or some dread throe of nature.