Often have I swept backward in imagination six thousand years, and stood beside our Great Ancestor, as he gazed for the first time upon the going down of the sun. What strange sensations must have swept through his bewildered mind, as he watched the last departing ray of the sinking orb, unconscious

whether he should ever behold its return. Wrapt in a maze of thought, strange and startling, his eye long lingers about the point at which the sun had slowly faded from his view. A mysterious darkness, hitherto unexperienced, creeps over the face of nature. The beautiful scenes of earth, which, through the swift hours of the first wonderful day of his existence, had so charmed his senses, are slowly fading one by one from his dimmed vision. A gloom, deeper than that which covers earth,

steals across the mind of earth's solitary inhabitant. He raises his inquiring gaze towards heaven, and lo! a silver crescent of light, clear and beautiful, hanging in the western sky, meets his astonished eye. The young moon charms his untutored vision, and leads him upward to her bright attendants, which are now stealing, one by one, from out the deep blue sky. The solitary gazer bows, and wonders, and adores. The hours glide by; the silver moon is gone; the stars are rising, slowly ascending the heights of heaven, and solemnly sweeping downward in the stillness of the night. The first grand revolution to mortal vision is nearly completed. A faint streak of rosy light is seen in the east; it brightens: the stars fade; the planets are extinguished the eye is fixed in mute astonishment on the growing splendour, till the first rays of the returning sun dart their radiance on the young earth and its solitary inhabitant. To him "the evening and the morning were the first day."

The curiosity excited on this first solemn night, the consciousness that in the heavens God had declared his glory, the eager desire to comprehend the mysteries that dwell in these bright orbs, have clung to the descendants of him who first watched and wondered, through the long lapse of six thousand years. In this boundless field of investigation, human genius has won its most signal victories. Generation after generation has rolled away, age after age has swept silently by, but each has swelled by its contribution the stream of discovery. One barrier after another has given way to the force of intellect; mysterious movements have been unravelled; mighty laws have been revealed; ponderous orbs have been weighed, their reciprocal influences computed, their complex wanderings made clear; until the mind, majestic in its strength, has mounted step by step up the rocky height of its self-built pyramid, from whose starcrowned summit it looks out upon the grandeur of the universe, self-clothed with the prescience of a God. With resistless energy it rolls back the tide of time, and lives in the configuration of rolling worlds a thousand years ago; or, more wonderful, it sweeps away the dark curtain from the future, and beholds those celestial scenes which shall greet the vision of generations when a thousand years shall have rolled away, breaking their noiseless waves on the dim shores of eternity.

To trace the efforts of the human mind in this long and ardent struggle; to reveal its hopes and fears, its long years of patient

watching, its moments of despair and hours of triumph; to develope the means by which the deep foundations of the rockbuilt pyramid of science bave been laid, and to follow it as it slowly rears its stately form from age to age, until its vertex pierces the very heavens; these are the objects proposed for accomplishment, and these are the topics to which I would invite your earnest attention. The task is one of no ordinary difficulty. It is no feast of fancy, with music and poetry, with eloquence and art, to enchain the mind. Music is here; but it is the deep and solemn harmony of the spheres. Poetry is here; but it must be read in the characters of light, written on the sable garments of night. Architecture is here; but it is the colossal structure of sun and system, of cluster and universe. Eloquence is here; but "there is neither speech nor language: its voice is not heard." Yet its resistless sweep comes over us in the mighty periods of revolving worlds.

Shall we not listen to this music, because it is deep and solemn? Shall we not read this poetry, because its letters are the stars of heaven? Shall we refuse to contemplate this architecture, because "its architraves, its archways, seem ghostly from infinitude?" Shall we turn away from this surging eloquence, because its utterance is made through sweeping worlds? No: the mind is ever inquisitive, ever ready to attempt to scale the most rugged steeps. Wake up its enthusiasm, fling the light of hope on its pathway, and no matter how rough, and steep, and rocky it may prove, ONWARD! is the word which charms its willing powers.

It is not my wish or design to introduce you to the dark technicalities of science, neither do I propose to rest satisfied with the barren statement of the results which have been reached by the efforts of genius. While on the one hand I shall endeavour to shun all attempt at critical scientific demonstration, which could only be intelligible to the professed student of astronomy, I shall on the other hand fearlessly attempt such an exposition of the processes and trains of reasoning by which great truths have been elicited, as to show to every intelligent mind that the problem is not impossible; by simplicity of language, by familiar illustrations, to fling light enough upon these mysterious propositions;—to show a pathway, though it be dim and rugged, still a pathway, which, if pursued, shall certainly lead to a full and perfect solution. I ask, then, no critical pre

vious knowledge of the subject, on the part of those who would follow me in the wonderful developments which I am about to attempt. Give me but your earnest and unbroken attention. Go with me in imagination, and join in the nightly vigils of the astronomer, and while his mind with powerful energy struggles with difficulty, join your own sympathetic efforts with his, hope with his hope, tremble with his fears, and rejoice with his triumphs. Lend me but this kind of interest, and my task is already half accomplished.

Before proceeding to an actual exposition of the structure of the Heavens, I propose in this introductory lecture to announce the nature of the problem, which the mind has essayed to resolve, and to point out the more important auxiliaries, mental and mechanical, which it has conjured to its aid. If the difficulties of this problem should overwhelm the mind, let it be remembered that the astronomer has ever lived, and never dies. The sentinel upon the watch-tower is relieved from duty; but another takes his place, and the vigil is unbroken. No: the astronomer never dies. He commences his investigations on the hill tops of Eden; he studies the stars through the long centuries of antediluvian life. The deluge sweeps from the earth its inhabitants, their cities and their monuments; but when the storm is hushed, and the heavens shine forth in beauty, from the summit of Mount Ararat the astronomer resumes his endless vigils. In Babylon he keeps his watch, and among the Egyptian priests he inspires a thirst for the sacred mysteries of the stars. The plains of Shinar, the temples of India, the pyramids of Egypt, are equally his watching-places. When science fled to Greece, his home was in the schools of her philosophers; and when darkness covered the earth for a thousand years, he pursued his neverending task from amidst the burning deserts of Arabia. When science dawned on Europe, the Astronomer was there, toiling with Copernicus, watching with Tycho, suffering with Galileo, triumphing with Kepler. Six thousand years have rolled away since the grand investigation commenced. We stand at the terminus of this vast period, and, looking back through the long vista of departed years, mark with honest pride the successive triumphs of our race. Midway between the past and future, we sweep backward and witness the first rude effort to explain the celestial phenomena: we may equally stretch forward thousands of years, and although we cannot comprehend what shall be the

condition of astronomical science at that remote period, of one thing we are certain; the past, the present, and the future, constitute but one unbroken chain of observations, condensing all time, to the astronomer, into one mighty now.

From the vantage ground which we occupy, it will not be difficult to announce so much of the great problem as has already been resolved, and to form some approximate conception of what remains for future ages to accomplish.

In the exposition about to be attempted, I do not propose to present any trains of reasoning, or any results which may have been reached. These shall engage our attention hereafter. At present, permit me simply to translate into language the questions which the visible heavens propound.

The most cursory examination of the celestial vault reveals the fact, that not one solitary object, visible to the eye, is at rest. Motion is the attribute of sun and moon, and planets and stars. The earth we inhabit alone remains fixed, to the

senses.

The first great problem propounded for human ingenuity, is to sever real motion from that which is unreal and only apparent. To accomplish this, some knowledge of the form of the earth which we inhabit must be obtained. Not only must we acquire a knowledge of its figure, but in like manner we must learn with certainty its actual condition, whether of rest or motion. If at absolute rest in the centre of the universe, then the rising sun, the setting moon, the revolving heavens, are real exhibitions, and must be examined as such. On the contrary, should it be found to be impossible to predicate of the earth absolute immobility, then arises the complicated question, how many motions belong to it? and with what velocity does it move? If a motion of rotation exist, what is the position of the axis about which it revolves, and is this axis permanent or changeable? If a motion of translation in space must be adopted, then whither is the earth urging its flight? what the nature of the path described ? the velocity of its movement, and the laws by which it is governed? These are some of the questions which present themselves in the outset, touching the condition of the earth, on whose surface the astronomer is located, in his researches over the heavens.

Beyond the limits of the earth, a multitude of objects present themselves for examination: and first of all the sun, the great