would naturally be produced simultaneously on the opposite side of the sphere, as an equipoise to the first, to keep equal the earth's motion; until all the heavy substances should be thrown out and united in a compact sphere. To an observer of the earth the crust every where appears to indicate the emergence of land from water: almost the whole surface of the solid crust is alluvial, and by reasoning and reflecting, we are led to the conclusion, that the solid parts of our globe are nothing more than a crust, and formed into concentric spheres, in accordance with the principles of projectile force. I would ask, what proofs have we, that the sphere we inhabit is solid beyond the degree of thickness necessary to preserve it from injury by its rapid motion round the sun, by its diurnal motion round its own axis, and by its motion round its common centre of gravity with the moon? It has been ascertained with mathematical certainty, that the large planet Jupiter, is more than 1300 times the bulk of the earth, and Saturn independent of his double ring, is about 1000 times the size. If we apply to those prodigious bodies, the reasoning of Newton relative to plastic forms moving variously, there is no just grounds for concluding that they are solid substances to their centres. If they were, their vast weight and remote position would require much more attraction than probably even the sun could furnish, to keep them within their orbits. The acknowledged and received laws of gravity, together with the measurements made on the same meridian, in different latitudes, have demonstrated to us that the greatest mathematicians have been mistaken as to the real figure of the earth. It is for schoolmen to make exact calculations, respecting the force of gravity, and centrifugal and centripetal forces; it is for them to determine with mathematical certainty where matter, left to its own laws, would settle; for such undertakings, I acknowledge my incompetency. But I have long had strong doubts, whether the laws of gravity are well understood; or whether the rules on which these calculations could be accurately made, are exactly known. However, I take the broad principles of nature, as presented to my view, for my guide; and draw my conclusions from what I have seen or what is well known to exist. Observe the boy hurling a stone from a sling; he whirls it round his head for a minute to acquire a certain degree of centrifugal force, and although it is not whirled with half the velocity the earth revolves on its axis, yet as soon as it is released from confinement, notwithstanding the whole power of the earth is operating on it with all the force of gravity, the centrifugal force which the stone acquired by the whirling is sufficient to carry it off, at a tangent to the circle described by the sling, for a very considerable distance, before the gravity of the earth and atmospheric obstruction can force it to the ground.