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cates its vibrations to the glass, which echoes the same sound; 2ndly-The window-frame being shaken, contributes to the noise. Brewer's Guide to Science.
ASTRONOMY, teaches us the magnitudes and distances of the heavenly bodies, their arrangements, their various motions and phenomena, and the laws by which their movements are regulated. It presents to our view, objects the most wonderful and sublime; whether we consider the vast magnitude of the bodies about which it is conversant-their immense number-the velocity of their motions-the astonishing forces requisite to impel them in their rapid career through the regions of the sky-the vast spaces which surround them, and in which they perform their revolutions-the magnificent circles they describe the splendour of their appearance-or the impor tant ends they are destined to serve in the grand system of
When we lift our eyes towards the sky, we perceive an apparent hollow hemisphere, placed at an indefinite distance,
and surrounding the earth on every hand. In the day time, the principal object which appears in this hemisphere is the In the morning, we see him rise above the distant mountains, or from the extremity of the ocean: he gradually ascends the vault of heaven, and then declines, and disappears in the opposite quarter of the sky. In the northern parts of the globe, where we reside, if, about the 21st of March, we place ourselves on an open plain, with our face towards the south, the sun will appear to rise on our left, or due east, about six in the morning, and about the same hour in the evening he will set due west. In the month of June, he rises to our left, but somewhat behind us, in a direction towards the north-east, ascends to a greater height at noon than in the month of March, and after describing a large arc of the heavens, sets on our right and still behind us, in the northwestern quarter of the sky. In the month of December, if we stand in the same position, we may observe, without turning ourselves, both his rising and setting. He rises in the south-east, ascends to a small elevation at noon, and sets in the south-west, after having described a very small arc of the heavens. Every day he appears to move a little towards the east, or contrary to his apparent diurnal motion; for the stars which are seen to the eastward of him, appear every succeeding day to make a nearer approach to the place in which he is seen. All the variety of these successive changes is accomplished within the period of 365 days 6 hours, in which time he appears to have made a complete revolution round the heavens from west to east.
The moon is the next object in the heavens which naturally attracts our attention; and she is found to go through similar variations in the course of a month. When she first becomes visible at new moon, she appears in the western part of the heavens, in the form of a crescent, not far from the setting sun. Every night she increases in size, and removes to a greater distance from the sun, till at last she appears in in the eastern part of the horizon, just as the sun disappears in the western; at which time she presents a round full-enlightened face. After this she gradually moves farther and farther eastward, and her enlightened part gradually decreases, till at last she seems to approach the sun as nearly in the east as she did in the west, and rises only a little before him in the morning, in the form of a crescent.
these different changes may be traced, by attending to her apparent positions from time to time, with respect to the fixed stars.
A dark shadow is occasionally seen to move across the face of the moon, which obscures her light, and gives her the appearance of tarnished copper. Sometimes this shadow covers only a small portion of her surface, at other times it covers the whole of her disk for an hour or two, and its margin always appears of the figure of a segment of a circle. This phenomenon, which happens, at an average, about twice every year, is termed an eclipse of the moon. It is produced by the shadow of the earth falling upon the moon, when the sun, the earth, and the moon are nearly in a straight line; and can happen only at the time of full moon. Sometimes the moon appears to pass across the body of the sun; when her dark side is turned towards the earth, covering his disk either in whole or in part, and intercepting his rays from a certain portion of the earth. This is called an eclipse of the sun, and can happen only at the time of new moon. In a total eclipse of the sun, which seldom happens, the darkness is so striking, that the planets and some of the larger stars are distinctly seen, and the inferior animals appear struck with
Again, if on a winter's evening, about six o'clock, we direct our view to the eastern quarter of the sky, we shall perceive certain stars just risen above the horizon; if we view the same stars about midnight, we shall find them at a considerable elevation in the south, having apparently moved over a space equal to one half of the whole hemisphere. On the next morning, about six o'clock, the same stars will be seen setting in the western part of the sky. If we turn our eyes towards the north, we shall perceive a similar motion in these twinkling orbs; but with this difference, that a very considerable number of them neither rise nor set, but seem to move round an immovable point, called the north pole. Near this point is placed the pole star, which seems to have little or no apparent motion, and which, in our latitude, pears elevated a little more than half way between the northern part of our horizon and the zenith, or point above our heads. A person who has directed his attention to the heavens for the first time, after having made such observations will naturally enquire-Whence come those stars which begin to ap
pear in the east? Whither have those gone which have disappeared in the west? and, What becomes, during the day, of the stars which are seen in the night?—It will soon occur to a rational observer, who is convinced of the roundness of the earth, that the stars which rise above the eastern horizon come from another hemisphere, which we are apt to imagine below us, and when they set, return to that hemisphere again; and that the reason why the stars are not seen in the day-time, is not because they are absent from our hemisphere, or have ceased to shine, but because their light is obscured by the more vivid splendour of the sun. such observations we are led to conclude, that the globe on which we tread is suspended in empty space-is surrounded on all sides by the celestial vault-and that the whole sphere of the heavens has an apparent motion round the earth every twenty-four hours. Whether this motion be real, or only apparent, must be determined by other considerations.
Such general views of the nocturnal heavens, which every common observer may take, have a tendency to expand the mind, and to elevate it to the contemplation of an Invisible Power, by which such mighty movements are conducted. Whether we consider the vast concave, with all its radiant orbs, moving in majestic grandeur around our globe, or the earth itself whirling round its inhabitants in an opposite direction-an idea of sublimity, and of Almighty energy, irre sistibly forces itself upon the mind, which throws completely into the shade the mightiest efforts of human power. The most powerful mechanical engines that were ever constructed by the agency of man, can scarcely afford us the least assistance in forming a conception of that incomprehensible Power which, with unceasing energy, communicates motion to revolving worlds. And yet such is the apathy with which the heavens are viewed by the greater part of mankind, that there are thousands who have occasionally gazed at the stars for the space of fifty years, who are still ignorant of the fact, that they perform an apparent diurnal revolution round our globe. Dick's Christian Philosopher.
1. What does Astronomy teach us? 2. What strikes us with wonder, in the objects it presents to our view?
3. What do we behold on looking to the sky?
4. Describe the daily course of the sun in our hemisphere ?
5. How will the sun rise and set, with regard to us, on the 21st of March? 6. How does he rise and set, in our part of the world, in June and December?
7. What is the length of the solar year? 8. In what time does the moon revolve round the earth?
9. In what part of the heavens does the new moon appear?
10. Where does the moon appear when full?
11. How does the moon move after becoming full?
12. Describe an eclipse of the moon. 13. What causes an eclipse of the moon, and when only can it happen?
14. What is an eclipse of the sun, and when does it happen?
15. If you watch the stars on a winter's evening, how will they seem to have moved, between six o'clock and twelve?
16. What about the motion of the stars in the northern part of the sky?
17. What about the position, and motion, of the pole star?
18. Whence come the stars that appear in the east?
19. Whither have those gone that disappear in the west?
20. Why are the stars not seen in the day time?
21. Are not the wisdom, power, and goodness of God, clearly manifested in the starry heavens?
22. Who is called the Sun of Righteous. ness, and why is he so called?
THE manner in which the blood-vessels are disposed in the human body bears some resemblance to the arrangement of the pipes by which a great city is supplied with water. London is supplied by means of an engine contrived for the purpose of distributing the water of the New River through the city. Large trunks are carried from this machine in different directions; smaller pipes branch out from these trunks into streets, lanes, and alleys; still smaller ones issue from them, and convey the water into private houses. So far the resemblance is complete. These water pipes represent the arteries which carry the blood from the heart to the extremities of the body; but in the human body another contrivance was necessary. The citizens of London may use the water or waste it as they please; but the precious fluid conveyed by the arteries to the ends of the fingers must be returned to the heart; for on its unceasing circulation our health depends.
In order to effect this purpose, another set of pipes is prepared, called veins, which joining the extremities of the arteries, receive the blood from them, and carry it back again to the heart. The veins present the same general appearance as the arteries; but as it is the office of the arteries to distribute the blood, so it is that of the veins to collect it.