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LECTURES ON ASTRONOMY.
The following pages were originally prepared in the form of a course of Lectures to be delivered before the Lowell Institute, of Boston, Mass., but, owing to the unexpected circumstance of the author's receiving no invitation to lecture before that institution, they were laid aside shortly after their completion.
Receiving an invitation from the trustees of the Vallecetos Literary and Scientific Institute, during the present summer, to deliver a course of Lectures on any popular subject, the author withdrew his manuscript from the dusty shelf on which it had long lain neglected, and, having somewhat revised and enlarged it, to suit the capacity of the eminent scholars before whom it was to be displayed, repaired tó Vallecetos. But, on arriving at that place, he learned with deep regret, that the only inhabitant had left a few days previous, having availed himself of the opportunity presented by a passing emigrant's horse,--and that, in consequence, the opening of the Institute was indefinitely postponed. Under these circumstances, and yielding with reluctance to the earnest solicitations of many eminent scientific friends, he has been induced to place the Lectures before the public in their present form. Should they meet with that success which his sanguine friends prognosticate, the author may be induced subsequently to publish them in the form of a text-book, for the use of the higher schools and universities; it being his greatest ambition to render himself useful in his day and generation, by widely disseminating the information he has acquired among those who, less fortunate, are yet willing to receive instruction.
The term Astronomy is derived from two Latin words, Astra, a star, and onomy, a science; and literally means the science of the stars. “It is a science,” to quote our friend Dick (who was no relation at all of Big Dick, though the latter occasionally caused individuals to see stars)," which has, in all ages, engaged the attention of the poet, the philosopher, and the divine, and been the subject of their study and admiration."
By the wondrous discoveries of the improved telescopes of modern times, we ascertain that upwards of several hundred millions of stars exist, that are invisible to the naked eyethe nearest of which is millions of millions of miles from the Earth ; and as we have every reason to suppose
every one of this inconceivable number of worlds is peopled like our own, a consideration of this fact-and that we are undoubtedly as superior to these beings, as we are to the rest of mankind is calculated to fill the mind of the American with a due sense of his own importance in the scale of animated creation.
It is supposed that each of the stars we see in the Heavens in a cloudless night, is a sun shining upon its own curvilinear, with light of its own manufacture; and as it would be absurd to suppose its light and heat were made to be diffused for nothing, it is presumed farther, that each sun, like an old hen, is provided with a parcel of little chickens, in the way of planets, which, shining but feebly by its reflected light, are to us invisible. To this opinion we are led, also, by reasoning from analogy, on considering our own Solar System.
THE SOLAR SYSTEM is so called, not because we believe it to be the sole system of the kind in existence, but from its principal body the Sun; the Latin name of which is Sol. (Thus we read of Sol Smith, literally meaning the son of Old Smith.) On a close examination of the Heavens we perceive numerous brilliant stars which shine with a steady light (differing from those which surround them, which are always twinkling like a dew-drop on a cucumber-vine), and which, moreover, do not preserve constantly the same relative distance from the stars near which they are first discovered. These are the planets of the SOLAR SYSTEM, which have no light of their own---of which the Earth, on which we réside, is one, which shine by light reflected from the Sun,—and which regularly move around that body at different intervals of time and through different ranges in space. Up to the time of a gentleman named Copernicus, who flourished about the middle of the Fifteenth Century, it was supposed by our stupid ancestors that the Earth was the centre of all creation, being a large flat body, resting on a rock which rested on another rock, and so on "all the way down;" and that the Sun, planets and immovable stars all revolved about it once in twenty-four hours.
This reminds us of the simplicity of a child we once saw in a railroad-car, who fancied itself perfectly stationary, and thought the fences, houses and fields were tearing past it at the rate of thirty miles an hour;—and poking out its head, to see where on earth they went to, had its hat one with pink ribbons-knocked off and irrecoverably lost. But Copernicus (who was a son of Daniel Pernicus, of the firm of Pernicus & Co., wool-dealers, and who was named Co. Pernicus, out of respect to his father's partners) soon set this matter to rights, and started the idea of the present Solar System, which, greatly improved since his day, is occasionally
a very nice
called the Copernican system. By this system we learn that the Sun is stationed at one focus (not hocus, as it is rendered, without authority by the philosopher Partington) of an ellipse, where it slowly grinds on for ever about its own axis, while the planets, turning about their axes, revolve in elliptical orbits of various dimensions and different planes of inclination around it.
The demonstration of this system in all its perfection was left to Isaac Newton, an English Philosopher, who, seeing an apple tumble down from a tree, was led to think thereon with such gravity, that he finally discovered the attraction of gravitation, which proved to be the great law of Nature that keeps every thing in its place. Thus we see that as an apple originally brought sin and ignorance into the world, the same fruit proved thereafter the cause of vast knowledge and enlightenment;-and indeed we may doubt whether any other fruit but an apple, and a sour one at that, would have produced these great results for, had the fallen fruit been a pear, an orange, or a peach, there is little doubt that Newton would have eaten it up and thought no more on the subject.
As in this world you will hardly ever find a man so small but that he has some one else smaller than he, to look. up to and revolve around him, so in the Solar System we find that the majority of the planets have one or more smaller planets revolving about them. These small bodies are termed secondaries, moons or satellites—the planets themselves being called primaries.