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LESSOS ICIS.

The Vaure asd Properties of Sounds

ALL sounds are produced by means of the air; but it is necessary for that purpose that the air should be in motion. It is not that erery movement of the air occasions a sound: for if this were the case, all wind must be attended by a noise. In order to form a sound, the air must be suddenly compressed; and must dilate and extend again by its elastic power. This occasions a kind of trembling undulation, something like that of the waves and circles occasioned by throwing a stone into the water. But if this undulating motion was only to be effected by the particles of air being compressed, the sound would never reach our ears. It is necessary that the sonorous bodies, after making impression on the contiguous air, should continue that impression from particle to particle all about us. By this means the particles of air 'reach our ear, and we have a perception of sound. This progress is made with great swiftness. Sound goes a thousand feet in a second of time, and consequently a German league in twenty, seconds. It is very remarkable that a weak sound propagates as quick as a loud one. The motion of the air, however, is stronger when the sound is stronger, because a greater mass of air is put in motion. A thin, elastic membrane, stretched at the bottom of the ear like a drum, receives the vibrations of the air; and by that means we have the

power of distinguishing sounds. 'If there were no sounds, all mankind would be dumb, and we should be as ignorant as a child before it can speak; but by means of sounds every creature can express its wants and its enjoyments. But if we enquire, how is it that, when we pronounce a word, it creates in us the idea of a word, and not a mere sound, or how a tone can act upon our souls, and produce so many different sensations, we are obliged to acknowledge our ignorance. It is enough for us to be convinced by this, as by every thing else, of the wisdom and goodness of our Creator.

LESSON C.

The Mysteries of Nature.

WHEN men attempt to penetrate into the causes of the effects daily under their observation, they are obliged to acknowledge how limited their understandings are. There are a great number of effects in nature concealed from us; and those which we are able to explain have still some obscurity in them, which reminds us that we are but men. We hear the wind whistle; we experience its great and different effects; but we know not exactly what produces it, what increases its violence, or what abates it. From a little grain we behold grass and ears of corn spring up; but we are ignorant how it is done, We still less comprehend, how from a little fruit-stone there can grow a plant, and then a great tree, under whose shade the birds make their nests; which tree is covered with leaves and blossoms, to shade us, and afford us fruit to eat, and wood for our use and convenience. We behold the wonderful effects of the loadstone, and we believe there must be a certain matter which operates in it; but whether it acts by an attractive force peculiar to itself, or whether it circulates continually round the loadstone, and forms a sort of vortex, is what we cannot decide. We feel the cold, but no man has yet discovered what occasions it. Nature, at every step, presents us wonders which confound us; and whatever researches or discoveries we have made, there still remain many things we cannot comprehend. It is true, we sometimes are able to give happy explanations of certain phenomena; but the principles, the first springs, their nature and manner of operating, are certainly above the sphere of our understanding.

The mysteries of nature afford us daily lessons of wisdom, in regard to the mysteries of religion. In nature, God has placed within our reach the means of passing our temporal lives happily, although he has concealed the causes from our sight. Thus, in the kingdom of grace, he furnishes us with means of arriving at a spiritual and everlasting life, though the manner in which they operate remains concealed from us. Would any one refuse to eat and drink, till he knew how it is that food gives him strength and preserves his life? Or would he neither sow nor plant, for want of having a just idea of the manner in which vegetation operates? If we find things which we cannot comprehend, or thoroughly know, let us receive them with humility, and acknowledge the weakness of our understanding. The advan, tages that they are of to us, when we make a good use of them, convince us that they are the work of a Being infinitely wise and beneficent; and this is sufr : ficient for us to know.

LESSON CI.

Fish.

Who that had never seen fish would have believed there were such creatures? If a naturalist only knew animals that walk and breathe on land, as the rein-deer does, and was told that there were creatures in the water, so formed as to live, move, multiply, and to fulfil every animal function in that element with ease and pleasure, would he not treat it as a fiction; and conclude, from the effect on our bodies, when plunged into water, that it is absolutely impossible to live in that situation. It is certain, that the way in which fish live, their construction, motion, &c. are quite wonderful, and afford fresh proofs of the omnipotence and infinite wisdom of our Sovereign Creator. To enable these creatures to live in water, it was necessary to form their bodies, in many essential points, very differently from those of land-animals; and we find this to be the case in fishes, both within and without. Thus the all-wise Creator has given to most fish a slender, thin body, flattened at the sides, and always a little pointed at the head, that they should swim, and cut their way better in the water ; and they are covered with scales of a horny substance, to preserve their bodies from being hurt by the pressure of the water. Those without scales are enveloped with a fat and oily substance, to preserve them from putrefaction, and to guard them from the cold. Their bones are different from other bones, to make their bodies more flexible. Their eyes are sunk into the head, to guard them from being hurt. It is evident, that in the formation of all those parts, the Creator has considered the way of life and destination of these animals. But there are still more wonderful circumstances in

their construction. The fins are almost their only limbs, and yet are sufficient to perform all their motions. By means of the tail-fins they move forward; the back fin directs the motion of the body; they raise themselves up by the breast-fin, and that of the stomach serves to balance them. The gills are their organs of respiration. These are behind their head. There are four on each side, the uppermost of which are the largest. They are continually swallowing water through their mouths, which is their drawing in of breath; and they cast it out through their gills, which is their way of breathing out again. The blood which comes from the heart, and flows into the veins of the gills, does not return back to the heart through the lungs, as in land animals, but it is directly dispersed throughout all parts of the body. One of the organs most necessary to fish in swimming, is the bladder of air in their stomach. By means of this bladder they make their body more or less heavy. When this vein swells and extends, they become lighter, can raise themselves, and swim to the surface of the water. When it contracts, and the air is thereby compressed, the borly becomes heavier than the water, and consequently sinks down.

The prodigious quantity of fish, with the great variety of shape and size, is worthy admiration. In Germany alone there are above four hundred species of fish? and who can count the numbers there are of each species? The very largest, as well as the smallest of animals, are to be found amongst fish. We ought to admire the power and wisdom of the Creator, in the forming and preserving of these aniwals, and his goodness in giving them for our use.

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