Of the gravity of bodies. JULY 27. DESIGN OF THE CREATOR WITH RESPECT TO THE GOD hath endued all bodies with a force by which they are compelled to act at all times, in all places, and in all directions. If the motion of a body tends more powerfully toward one point than to another, we say that it gravitates toward that point; for experience teaches us that bodies have a tendency to descend, or that when they are at a considerable distance from the ground, and are not sup ported, they fall down perpendicularly to the earth. The reason of this gravitation cannot lie in the body itself, for a falling body remains in the state in which it was first placed, till it is changed by some external cause. It is equally impossible that the air should be the cause of this gravitation, for, possessing weight itself, it would rather retard the velocity of falling bodies. We must therefore presume the existence of a very different cause. haps we shall come nearest to the truth, if we adopt this opinion, that the earth possesses the power of attracting all bodies that are within a certain distance, in the same manner as the magnet attracts iron; or perhaps the cause of gravity is to be imputed to some particular extraneous matter diffused through all bodies. Per Though we are unable exactly to ascertain the cause of gravity, yet nothing can be more evident than the advantages resulting from it. To go no farther than ourselves, without gravity we should not be capable of moving our bodies as we do. Our centre of gravity is between our feet. When we VOL. III.-NO. 16. Of the gravity of bodies. raise the right leg, we must first transfer this centre of gravity to the left. If we bend forward we are ready to fall; but by advancing the right leg we prevent our fall, and make a step. Thus walking is a continued series of falls, during which the centre of gravity is always preserved between the legs. Hence we bend the body forward when we ascend a hill, and backward when we descend. We incline forward when we carry a burden on our shoulders, and backward when we carry it before us. All this proceeds from the laws of gravity, by which all the motions of animals in walking, swimming, and flying are regulated. The motions of the prodigious orbs that roll in the heavens are produced by gravity. The sun at tracts the planetary system, and each planet in its turn attracts its satellites; or, what amounts to the same thing, the planets gravitate toward the sun, and the satellites toward their respective planets; for a body whirled round in a circle flies off in a right line from the centre of its motion, unless it be held by some power. The planets revolve in. their orbits with great velocity, and the moon is not bound by any chain to the earth. Her rapid motion must infallibly hurl her to an immense distance in immeasurable space, were she not conti nually impelled toward our globe by a power which counterbalances the force that tends to propel her from the earth. This power is gravity. Were our earth heavier or lighter than it actually is, what would be the consequence? It would either ap proach very near to the sun, or fly off to a prodigious distance from that luminary. In the former case the heat, and in the latter the cold would be insupportable. Every thing on the face of the 1 Manifold effects in Nature from the same cause. globe would be consumed or frozen. What would then become of the seasons, and a thousand other things which are indispensably necessary for the support and convenience of man? In this dispensation also, O Being supremely wise, hast thou established a monument of thy wonders. By a medium apparently so simple hast thou regulated the motions of the insect, and of the immense orbs which roll in the firmament. By the laws of gravity alone thou hast prevented the smallest atom belonging to the earth, or to any of the other planets, from being lost. But herein consists the infinite greatness of thy power and wisdom, that by the simplest, nay, even apparently the most contemptible means, thou art able to produce the most astonishing effects. How different art thou in this respect from men, who are often obliged to make great preparations for the accomplishment of trivial and unimportant ends. He who cannot herein discover thy greatness, must be either exceedingly inattentive or exceedingly ungrateful. I will carefully avoid both of these faults. Henceforward I will consider the gravitation of bodies as one of the means of promoting my happiness on earth, and praise thee for it with all my heart and with all my soul. JULY 28. MANIFOLD EFFECTS IN NATURE PROCEEDING FROM THE SAME CAUSE. THE whole system of Nature is an endless series of causes and effects. As all the parts of the universe bear a relation to each other, every motion Manifold effects in Nature from the same cause. and every incident depends on previous causes, and itself becomes the cause of succeeding effects. The whole constitution of the world convinces us, that it was not chance, but a divine art and wisdom surpassing all human conception, that reared this magnificent fabric, that imparted certain motions to its different parts, and determined the great chain of events, which are to depend upon and to succeed each other. This degree of knowledge it is not difficult to attain; for though our acquaint'ance with Nature is confined within very narrow limits, yet we are able to discover that many great and important effects result from causes that are equally obvious to our senses and our understanding. Of this, numberless phenomena of Nature may afford a demonstration. What a variety of effects are manifestly produced by the heat of the sun! It contributes, not only to the life of innumerable ani mals, but likewise to the vegetation of plants, to the ripening of every species of seeds and fruits, to the fluidity of water, to the exhalation of vapors, and the formation of clouds, without which we should have neither rain nor dew. The air, in like manner, is constituted with such art as to answer various purposes. By means of this element, animal life is maintained, and all the vital energies are kept up. By air, fire is fed, and combustion produced; all kinds of sounds are conducted by rapid vibrations to the ear; the feathered tribes are aided in their flight from place to place; and a path is opened for man across the wide and trackless expanse of ocean. By the air the clouds are supported, till, overcharged with humidity, they descend rain; by means of air the day is prolonged by Manifold effects in Nature from the same cause. the morning and evening twilight, and speech is given to the tongue, and hearing to the ear. All these, and other advantages are derived from the constitution of the air in which we live and breathe. Is not, thẹn, this wonderful and useful element which surrounds our globe, which, though too subtle to be discerned with the eye, is endued with... a force which no other element can resist ;—is it not, I say, an evident demonstration of the wisdom of our Creator? The mere power of gravitation, which exists throughout all Nature, gives solidity to the globe and fluidity to the waters. It retains the ocean within its abysses, and confines the earth to her prescribed orbit: it keeps the spheres at due distances, and every object in Nature in its proper place. How multifarious are the uses of water! It serves generally to dilute, soften, and dissolve many substances, which otherwise would be unserviceable to us. It is the most wholesome beverage, works mills and other machines, is the principal nourishment of plants, supplies us with abundance of fish, and wafts to us on its bosom treasures from all the regions of the globe.-What various and innumerable effects are produced by the element of fire. By means of it solid substances are reduced to a fluid state, or transformed into solid bodies of a different nature; and fluids are boiled or evaporated. It communicates warmth to all bodies, and produces the sense of sight in the eyes of living creatures.* * This observation, it will be perceived, is founded on the theory which supposes light to be a modification of the matter of fire. T. |