nite ideas can be conveyed to the mind of the the principles of the science, by being taught student on this subject.* SECTION VIII.-Astronomy. to observe, with their own eyes, the motions and general phenomena of the heavens. The first object to which their attention might be di rected, is the apparent motion of the sun. On some clear evening in the month of June, (in our northern latitude,) they may be placed in a situation where they may behold the setting sun, and be desired to take particular notice Astronomy is a science which has for its object to explain the motions of the heavenly bodies, their various aspects, and the facts which have been ascertained in the planetary system, and throughout the region of the fixed stars. This is a subject of considerable of such objects as mark the place of his going interest and utility. It is intimately connected down. Next morning, or the first clear morn with geography, navigation, agriculture, com- ing afterwards, they may be placed in the merce, chronology, and other arts and sciences, same situation, and, having first requested and has lent its aid to promote their improve them to point to the place where the sun dis ment. The study of it is likewise attended appeared the evening before, their attention with many pleasures and advantages in a should next be directed to the point of his moral, intellectual, and religious point of rising, and to mark the terrestrial objects in view. It expands the range of the human the direction of which he appeared to rise. intellect, and unfolds to our view the most The difference between the points of his setstriking displays of the perfections of the ting and of his rising should be particularly Deity, particularly the grandeur of his Omni- impressed upon their minds. On this day, potence. It sets before us objects of overpow- too, about twelve o'clock, they should be diering magnitude and sublimity, and demon- rected to attend to the sun's meridian altitude. strates the unlimited extent and magnificence These observations may either be accompa of the universal empire of the Almighty. It nied with certain appropriate remarks, or the has a tendency to raise the soul above grovel- pupils may be left, in the mean time, to rumiling pursuits and affections, to inspire hope, nate upon them, to consider them simply as reverence and humility, and to excite to the facts, which may be afterwards adverted to, contemplation of objects far surpassing every and to form their own conclusions. Similar thing we behold in this terrestrial scene, and observations may be made from the same spot worthy of the dignity of immortal minds. In about the 23d September, and particularly short, it prepares the mind for the employments of the future world, and demonstrates that the Creator has it in his power to distribute endlessly diversified streams of felicity, among every order of his intelligent offspring, throughout all the revolutions of eternity. It is a subject, therefore, on which a certain portion of information should be communicated to the young, and to every human being. In communicating to the young instructions on this subject-instead of commencing with definitions of astronomical terms, and a vague description of the solar system, as is frequent ly done, the pupils should be gradually prepared for acquiring a general knowledge of * Books on geology have, of late years, increased both in number and in the interesting nature of the discussions they contain. The names of Bakewell, Macculloch, Delabeche, Buckland, Ure, Lyell, &c. are well known as cultivators of this depart ment of natural science. The new edition of Mr. Lyell's "Principles of Geology," in 4 vols. 12mo. about the middle of December, when the direction of the rising and setting sun, his meri dian altitude, and the apparent diurnal are he describes, will appear very different, when compared with the observations made in the month of June. Their attention might next be directed to the phases and motions of the moon. About three days after new moon, when the lunar crescent first makes its appearance, they may be directed to mark the form of the crescent, the most conspicuous stars in its vicinity, and its apparent distance from the place where the sun went down. Every clear evening afterwards, the gradual increase of the crescent, its motion among the stars, and the apparent distance it has moved during every successive period, should be particularly marked, till it arrive at the eastern part of the horizon after the sun has set in the west, when it will appear a full enlightened hemisphere. During the months lately published, perhaps one of the most luminous and attractive works which has hitherto of August, September, and October, when the been published on this subject though perhaps effect of the harvest-moon is apparent, they somewhat deficient in what relates to primary and secondary rocks, and embodying certain stmary may be directed to trace the gradual diminu ments which some will be apt to consider as tion of the full moon, through its different scarcely consistent with the records of sacred stages of decrease, till it assume the form of a history. Dr. Comstock, of Hartford, State of Con- half moon or a necticut, has lately published, in a duodecimo vol. large crescent. During the of about 340 pages, an interesting work, entitled, months of March or April, their attention "Outlines of Geology," which contains a popular may be directed to the difference in the time and comprehensive view of this subject, and is of its rising on each successive day after full peculiarly adapted to the instruction of general readers. (108) moon, from what takes place during the DIURNAL MOTION OF THE HEAVENS. months of harvest, in the one case, namely, in harvest, there being only 20 minutes of difference after full moon, in its rising on each successive day; while in spring, the difference is nearly an hour and a half, which prevents her, at that season, from being seen in the form of a half-moon, during her decrease, till early in the morning; whereas, in harvest, she may be seen rising in the northeast, in the form of a half-moon, about 8 or 9 in the evening. They may next be directed to attend to some of the principal stars, and the more conspicuous constellations, and particularly to the apparent diurnal motion of the whole celestial vault. The month of January is perhaps the most eligible season for such observations. About the middle of that month, at eight o'clock in the evening, the most striking and brilliant constellations visible in the northern hemisphere are then above the horizon. The Pleiades or Seven stars, and other portions of the constellation Taurus, are nearly on the meridian, at an elevation of above 60 degrees. The splendid constellation Orion, to the south of Taurus, is a little to the east of the meridian; Canis Minor to the east, and Canis Major to the south-east of Orion. Nearly due east and near the horizon, is the zodaical constellation Leo. To the west of the meridian are the constellations Aries, Pisces, Cetus, Andromeda, Pegasus, and Cassiopeia, which is not far from the zenith. To the north-east is Ursa Major, or the Great Bear, sometimes distinguished by the name of the Plough, or Charles's Wain. The star Aldebaran, or the Bull's eye, is nearly on the meridian, at an elevation of 54°, supposing the place of observation to be in 52° north latitude. It is distinguished by its ruddy appearance. The brilliant star Capella is nearly 32° north by east from Aldebaran, not far from the zenith; and Rigel, in the left foot of Orion, is about 27° south by east of Aldebaran, and a little 109 so as to become invisible once in a period of 334 days. The brilliant star Lyra is northnorth-west, very near the horizon. The two stars in the Great Bear, called the Pointers, are in a direction nearly north-east from Castor and Pollux, but at a considerable distance; they direct the eye to a star of the second magnitude, in Ursa Minor, at a considerable distance towards the west, called Abruccabah, or the Polestar. Having pointed out these leading stars and constellations, to serve as so many known points in the heavens, the attention might be directed, on a subsequent evening, about six o'clock, to the apparent motions of these bodies, and of the whole celestial sphere. On the evening of January 16th, at six o'clock, the star Procyon will be seen nearly due east, a very little above the horizon; Aldebaran, in an easterly direction, nearly halfway between the meridian and the eastern horizon: Rigel, towards the south-east, a little above the horizon; and Lyra, in the north-west, about 15 degrees above the horizon. Having marked the terrestrial objects which appear in the direction of these stars, they may be viewed, from the same station, about two hours afterwards, when Procyon will be found to have risen a considerable way above the horizon; Rigel, to have moved nearly 30 degrees to the westward; and Aldebaran, to have arrived near the meridian; while Lyra has descended within two or three degrees of the horizon; and Sirius, which was before under the horizon, is elevated about ten degrees above it. At ten o'clock, the same evening, Rigel and Aldebaran will be seen at a considerable distance westward of the meridian; Sirius, within 6 or 7 degrees of it; the star Lyra, near the northern horizon; and the constellation Orion, which in the first observation appeared in the direction south-east by east, will be found to have moved to the westward of the meridian, By such observations, it may be shown that east of the meridian. Betelgeux is north-east the whole starry firmament has an apparent from Rigel, and forms a right angled triangle diurnal motion from east to west. While with it and Aldebaran. The stars Castor and pointing out these apparent motions to the Pollux are east by north from Aldebaran, at young, it will be proper to direct their attena considerable distance from it, (45°,) and tion to the polestar, which, to a common nearly halfway between the zenith and the observer, never appears to shift its position. eastern horizon. Nearly straight south from They may likewise be directed to notice that Pollux and east from Betelgeux, is Procyon, the stars near the pole appear to move slower, These three stars form a right-angled triangle, and to describe smaller circles than those at a the star Procyon being at the right angle. greater distance from it-that those which Near the south-eastern part of the horizon, rise near the south describe smaller arcs than told, at the same time, at what distance the yard or foot is supposed to be placed from our eye. As astronomers divide the circumference of the celestial sphere into 360 parts or degrees, they may be told, that from any point of the horizon to the zenith are 90 degrees, and, consequently, that from the eastern to the western, or from the northern to the southern points of the horizon, are 180 degrees. And, in order that they may have a definite idea, or something approximating to it, of the extent of a degree, they may be told that the breadth of the moon is about half a degree-that the space occupied by the three stars in a straight line in the belt of Orion-sometimes distin guished by the name of the Three Kings, or the Ell and Yard-is exactly 3 degrees in length, and, consequently, the distance be tween any two of them is a degree and a half and a little elevated above it, is Sirius, or the Dog-star, which is generally reckoned the most brilliant fixed star in the heavens. West from Rigel at a considerable distance, (46°,) and at nearly the same elevation above the horizon, is Mira, or the Wonderful star which changes from a star of the second magnitude, those which rise farther to the north-that the stars which rise due east, set due west, after an interval of twelve hours that the stars which rise in the north-east, after describing a large arc of the heavens, set in the north-west, after an interval of about seventeen hours that all the stars within a certain distance of the pole never appear to rise or set, but de- altogether vague and indefinite, unless we are scribe complete circles above the horizonthat the stars near the pole, such as those in the Great Bear, appear in one part of their course to move from west to east, and in another part of it from east to west-and that the revolutions of the whole, however different the circles they apparently describe, are completed in exactly the same period of time. These positions may afterwards be more particularly illustrated by means of a large celestial globe, by which it will be seen that all these appearances are the result of one general apparent motion, which, at first view, will appear to exist in the celestial sphere. An idea of the general motion of the stars may be acquired by a simpler process than what we have now described. Let any observer bring a star, in any position between the zenith and southern horizon, into an apparent contact with a tree, spire, or chimney-top, and, in the course of that the distance between Castor and Polluz fifteen or twenty minutes, he will perceive that that star and others adjacent to it have moved a little space from east to west. But degrees and that the space between Dubbe, the observations alluded to above are calculated to give a more satisfactory idea of this motion, and to make a deeper impression on the minds of the young. is nearly 5 degrees between Dubbe and Mo rah, the two Pointers, in the Great Bear, is 5 or the northermost pointer, and the polestar, is about 29 degrees. By familiarizing the mind with such measures, the young will soon acquire a tolerable idea of the distance of any two objects in the heavens, when the number of degrees is mentioned. All the observations above stated may be made, in the way of an amusement, previous to the time when the pupils are expected to enter on the regular study of astronomy. They may be completed in the course of ten or twelve observations, made at different times, within the space of seven or eight months. They are intended for the purpose of stimu lating the young to habits of observation and attention to the appearances of nature around them; so that, in every clear sky, they may learn to make similar observations by themselves, for confirming and amplifying their former views of the motions and aspects of the heavens. Such observations form the groundwork of astronomy, and of all the instructions they may afterwards receive in relation to this science, although they are generally neglected. The next series of observations might be those which demonstrate the apparent annual motion of the sun. For the purpose of exhibiting this motion, the Pleiades, or seven stars, along with Aldebaran, might be selected as fixed points in the heavens to indicate the progressive motion of the solar orb towards the east. About the middle of January, at eight o'clock in the evening, the Pleiades will be seen on the meridian; which observation should be noted down, for the purpose of being compared with a future observation. On the 1st March, at the same hour, these stars will be seen nearly halfway between the meridian and the western horizon, while all the other stars, at the same declination, will be found to have made a similar progress. About the 15th April, they will be seen, at the same hour, very near the western horizon; and every day after this, they will appear to make a nearer approach to that part of the heavens in which When problems on the celestial globe are pre the sun appears, till, being overpowered by the scribed, and vague descriptions of the planetary system given, previous to having made these observations, the subject is seldom understood. and no clear nor expansive conceptions formed by the young, of the motions, phenomena, and relations of the great bodies of the universe. It may not be necessary, in the first instance, while making these observations, to attempt any explanation of the phenomena, but merely splendour of his rays, they cease to be visible. From these and similar observations, it will be easy to make the young perceive, that the sun has an apparent motion from west to east, through the circle of the heavens, and that the revolution is completed in the course of a year. They may next be taught to acquire a definite idea of the measures by which the apparent distances of objects in the heavens are to impress upon the mind a clear conception expressed. To talk to the young, as some of the apparent motions and relative aspects, are in the practice of doing, of two stars being of the celestial orbs, as they present themselves a foot, a yard, or two yards asunder, is to an attentive spectator; leaving the pupil to APPARENT MUTIONS OF THE PLANETS. 111 ruminate upon them till it shall be judged as seen from the earth, are in perfect accordproper to direct his attention to the investiga- ance with a regular circular motion around tion of the true causes of celestial phenomena. the sun as a centre; and that such apparently irregular movements arise from the motion of the earth, and the different velocities of the planets, when compared with it, just as the objects around us appear to move in different directions, and with different velocities, when we are sailing along a serpe..ri iver in a steamboat. The pupil's attention might be next directed to the motions of the planets, and the general phenomena of the solar system. When any of the planets are visible in the heavens, their positions in relation to the neighbouring stars should be particularly noted, so that their apparent motions, whether direct or retrograde, may be clearly perceived, which, in most cases, will be quite perceptible in the course of a few weeks or months. The direct, stationary, and retrograde movements of Mars and Venus should be particularly attended to, for the purpose of afterwards demonstrating that the annual motion of the earth accounts for the apparently irregular and complicated motions of the planetary orbs. Large diagrams, representing the apparent motions of Mars, Mercury, and Venus, as seen from the earth during the course of several revolutions, with all the apparently irregular loops and curves they appear to describe*-should be laid before the pupil for his particular inspection, in order that he may perceive the improbability that such motions are real, or that an Infinitely Wise Being, who is the Perfection of Order, would introduce such inextricable confusion into the motions of the most splendid of his works-A common planetarium, which shows by wheelwork, the relative motions of Mercury, Venus, the Earth, and Mars, may be easily made to illustrate these motions, and to solve all their phenomena. Let a circle, two or three inches broad, and and that such motions, if they actually ex The arguments or considerations which prove that the Earth is a moving body, should next be presented to the attention, and illustrated in the most simple and familiar manner of which the subject will admit. The pupil will easily be made to perceive, that, if the earth is at rest, the whole frame of the material universe must move round it every twentyfour hours; not only the fixed stars, but the sun and moon, the planets and their satellites, and every comet which traverses the firmament, must participate in this motion, while, at the same time, they are moving in another and an opposite course peculiar to themselves. He will perceive, that, in proportion as these bodies are distant from the earth, in a similar proportion will be the velocity with which they perform their diurnal revolutions-that the sun behoved to move five hundred and ninetyseven millions of miles every day, the nearest fixed star 125,000,000,000,000 of miles in the same time, or at the rate of fourteen hundred millions of miles every second, and the most distant stars with a velocity which neither words can express, nor imagination conceive, isted, would, in all probability, shatter the whole material frame of the universe to atoms. of such a diameter as to surround the planets, with a few stars marked on its inside to represent the Zodiac, be suspended on three pillars, He may be directed to consider, that such ra so as to inclose the Earth, Mercury, and Venus. Let a wire be fixed by a socket, on the top of the pillar which supports the ball representing the Earth, and let this wire rest on a slit or fork fixed to the top of the pillar which supports the ball representing Mercury. pid velocities (if they could be supposed to exist) are not the motions of mere points or small luminous balls, but the motions of immense globes, many thousands of times larger than the earth-that a hundred millions of such globes are visible from our abode, besides When the machine is set in motion, the wire the myriads that may be hid from human view will point out on the Zodiac the apparent in the unexplored regions of space-and that motions of Mercury as seen from the earth. it is impossible to conceive how all these inWhen he passes from his greatest elongation numerable globes, of different magnitudes, at westward to the superior conjunction and to his greatest elongation eastward, the wire will move eustward, according to the order of the signs. About its greatest elongation, it will appear stationary, and immediately afterwards will move westward, or contrary to the order of the signs, till it arrive at the western elongation, when it will again appear stationary ;so that the pupil will plainly perceive that the direct and retrograde motions of the planets, * Specimens of such diagrams may be seen in Long's Astronomy," vol. i., and in plate 3 of "Ferguson's Astronomy," Brewster's edition. different distances, and moving with different velocities, could be so adjusted as to finish their diurnal revolutions at the same moment, while many of them are at the same time impelled by other forces in a contrary direction. He may be reminded that the Creator, who formed the universe, is possessed of INFINITE WISDOM-that wisdom consists in proportionating means to ends, or in selecting the most appropriate arrangements in order to accomplish an important purpose-that to make the whole frame of Universal Nature move round the earth every day, merely to produce the alternate succession of day and night, is re- riods assigned them in the system which have pugnant to every idea we ought to entertain the sun for its centre. From such consideraof the Wisdom and Intelligence of the Divine tions, when properly explained, the annual Mind, since the same effect can be produced motion of the earth, and its relative position by a simple rotation of the earth in twenty- in the system, may be clearly demonstrated, four hours; and since we find that Jupiter and the pupil made to perceive the beauty and and Saturn, and other globes much larger than harmony of the celestial motions, and the neours, move round their axes in a shorter period cessity of having the great source of light and -that in all the other works of Omnipotence, heat placed in the centre of the system. For means apparently the most simple are selected to accomplish the most grand and magnificent designs-and that there is no example known to us, throughout the universe, of a larger body revolving around a smaller. When such considerations are fully and familiarly illustrated, the pupil will soon be made clearly to perceive, that the rotation of the earth must necessarily be admitted, and that it will fully account for all the diversity of diurnal motion which appears in the sun and moon, the planets and the stars. as the sun is intended to cheer and irradiate surrounding worlds, it is from the centre alone that these agencies can be communicated, in a uniform and equable manner, to the planets in every part of their orbits. Were the earth the centre, and the sun and planets revolving around it, the planets when nearest the sun, would be scorched with excessive heat, and when farthest distant would be frozen with excessive cold. There is another consideration by which the earth's annual revolution and its position in the system are demonstrated; and that is, that the planets Mercury and Venus, when viewed through good telescopes, are found to assume different phases, in different parts of sometimes like a half-moon, and at other times sphere, which could never happen if they re volved round the earth as their centre, and if the earth was not placed in an orbit exterior to second, may be seen even at noonday. Venus may be seen by this instrument, in the day. time, during the space of nineteen months, with the interruption of only about thirteen days at the time of her superior conjunction, and three days at the time of her inferior, so that the phase she exhibits may be seen almost every clear day. Having placed the Earth The annual revolution of the earth, and its position in the solar system, might be proved and illustrated by such considerations as the following:-that if this motion did not exist, the motions of all the planets would present their orbits; sometimes appearing gibbous, a scene of inextricable confusion, consisting of direct and retrograde motions, and looped like a crescent, and a full enlightened hemicurves, so anomalous and irregular, as to be inconsistent with every thing like harmony, order, or intelligence-that Mercury and Ve. nus are observed to have two conjunctions that of Venus. I have sometimes illustrated with the sun, but no opposition; which could this argument, with peculiar effect, by means not happen unless the orbits of these planets of an equatorial telescope and a common planelay within the orbit of the earth-that Mars, tarium. By the equatorial telescope, with a Jupiter, and the other superior planets, have power of 60 or 80 times, most of the stars of each their conjunctions with and oppositions the first magnitude, and some of those of the to the sun, which could not be unless they were exterior to the orbit of the earth-that the greatest elongation of Mercury from the sun is only about 20 degrees, and that of Venus 47; but if the earth were the centre of their motions, as the Ptolemaic system supposes, they might sometimes be seen 180 degrees from the sun, which never happensthat some of the planets appear much larger and Venus in their true positions on the plane and brighter at one time than at another, on tarium, by means of an Ephemeris or the Nau account of their different distances from the tical Almanac, I desire the pupil to place his earth; but, on the other hypothesis, their eye in a line with the balls representing these brilliancy should be always the same-that planets, and to mark the phase of Venus as seen Mercury and Venus, in their superior con- from the earth-whether a crescent, a halfjunctions with the sun, are sometimes hid moon, or a gibbous phase. I then adjust the behind his body, and in their inferior conjunctions sometimes appear to pass across the sun's disk, like round black spots which would be impossible according to the Ptolemaic system; -and, in short, that the times in which the conjunctions, oppositions, stations, and retrogradations happen, are not such as they would be if the earth were at rest, but precisely such as would happen, if the earth move along with all the other planets, in the stations and pe- half of its course from one conjunction to au equatorial telescope for Venus, if she is within the range of our view, and show him the planet with the same phase in the heavens. This exhibition never fails to gratify every observer, and to produce conviction. But it can seldom be made, if we must wait till the planet be visible to the naked eye, and capable of being viewed by a common telescope; for it is some times invisible to the naked eye, for nearly one |