which visited France in 1789; so Madison, the great legislator of 1787, prepared the way for the angel of Extermination, which, in 1861, visited the South. But the demonstration of this truth must be reserved for some future number of THE SOUTHERN REVIEW.1

More than once, in the course of the preceding reflections, have the eloquent words of a great writer occurred to our minds; covering the whole ground we have so feebly occupied, and far more. The words in question being, in fact, as pertinent to the present discussion as they are eloquent, we shall here introduce them. 'All the speculations and schemes of the sanguine projectors of all ages', says John Foster, 'have left the world still a prey to infinite legions of vices and miseries; an immortal band, which has trampled in scorn on the monuments and dust of self-idolizing men who dreamed, each in his day, that they were born to chase these evils out of the earth. If these vain demi-gods of an hour, who trusted to change the world, and who perhaps wished to change it only to make it a temple to their fame, could be awakened from the unmarked graves into which they sunk, to look a little around the world for some traces of the success of their projects, would they not be eager to retire again into the chamber of death, to hide the shame of their remembered presumption? Hitherto the fatal cause of these evils, the corruption of the human heart, has sported with the weakness, or seduced the strength, of all human contrivances to subdue them. Nor do I perceive any signs, as yet, that we are commencing a better era, in which the means that have failed before, or the expedients of some new and happy invention, shall become irresistible, like the sword of Michael, in our hands. The nature of man, "Still cast ominous conjecture on the whole success." While that is corrupt, it will pervert the very schemes and operations by which the world should be improved, though their first principles be as pure as heaven; and revolutions, great discoveries, augmented science, and new forms of polity, will become in effect what may be called the sublime mechanics of depravity.'

4 The intelligent reader will, of course, bear it in mind, that Turgot and Madison are selected as the subjects of our remarks, because they were 'representative men', and because they were among the most influential of those by whom the great Error of the Eighteenth Century was embraced and reduced to practice, or embodied in institutions.

There is, it must be admitted, one difference between the French Revolution of 1789 and the American Revolution of 1861. The one was instigated by infidel philosophers; the other, by professedly religious preachers. This difference is, however, more nominal than real. For the preachers, having adopted the political maxims of the philosophers, were animated by the same spirit of revolt against the eternal laws of heaven and earth. In open defiance of their own creeds, as well as in proud contempt of the principles of the Bible, with respect to the nature of man, they embraced the anarchic maxims of the infidel philosophers of the eighteenth century, and proceeded to set the New World on fire. Hence both Revolutions had their roots in the same great error, were nourished by the same fell spirit, and brought forth the same fruits of desolation and death. It was precisely the same virus which convulsed and devoured France in 1789 and America in 1861. It was not as Christian divines, but as infidel dreamers and reformers, that the Beechers, the Tyngs, the Cheevers, and the McIlvaines, of the North, trod in the fatal footsteps of the Voltaires, the Rousseaus, and the Raynals, of France. Heaven have mercy on their poor deluded souls! But we shall not spare their errors. On the contrary, we shall, in some future number of this REVIEW, expose the radical opposition to their political maxims to the principles and the spirit of the religion which they profess, and upon which they have, by their worse than infidel practice, brought such infinite and ineffacable disgrace.

ART. II.-1. Répertoire d'Optique Moderne. Par l'Abbé Moigno. Paris: A. Franck. 1847.

2. Euvres de François Arago. Publiées d'après son ordre sous la direction de M. J. A. Barral. Paris: Gide, éditeur. 1858.

3. Familiar Lectures on Scientific Subjects. By Sir John F. W. Herschel, Bart., K. H., M. A., etc. London: Alexander Strahan. 1867.

4. Faraday as a Discoverer. By John Tyndall. New York: D. Appleton & Co. 1868.

A fool can ask more questions than a wise man can answer. However far we may analyse any fundamental subject, we are compelled to pause at those outer limits which may be called the corner posts of nature. The unsatisfactory results of many philosophical systems may doubtless be traced to the effort made to define those primitive elements of all definitions which can not, in the nature of things, be subject to limitations. Seneca well contrasts some of the dismal conclusions thus reached. 'If', says he, 'I believe Protagoras, there is nothing in nature but doubt; if Nausiphanes, this thing only is certain, that nothing is certain; if Parmenides, every thing is but one thing; if Zeno, every thing is nothing.' Nothing approaches, in august origin and abstruse nature, more nearly to the elemental mystery of life itself, than light, the 'first-born of Heaven',-offspring, indeed, of the earliest recorded utterance of the creative Power. What is light?' is a question to which we may frankly reply, as to a thousand similar ones touching the primitive mysteries of the universe, that we do not know. Yet there is a great deal about light which we do know,- many most wonderful facts, out of which and for the explanation of which the mind strives to build up a reasonable theory of the nature of light. To define it as an agency subject to certain laws and producing such and such results, by no means satisfies the inquiring understanding. As yet, however, we can scarcely do more.

Three fundamental laws of light are as follows:

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1o. Itself invisible, it renders all material objects within its sphere of action visible.

2o. For any given medium it acts in right lines, in all directions from the luminous body.

3°. This action proceeds at an enormous velocity.

The invisibility of light may strike one, at first, as a thesis out of Anaxagoras, who, according to Cicero, proved to the satisfaction of his own senses that snow is black. Nevertheless, it

is true. Take a box the inner walls of which are, like the chamber of a camera, thoroughly blackened. In one face puncture a pin-hole and admit a ray of light. If, through a blackened tube inserted in the upper side immediately over the line of the ray, we gaze down into the chamber, all is darkness. The light is there, however; for, on lowering by a thread through the tube a silvered bead into the line of the ray, its star-like reflection will instantly spring into view. A sunbeam, indeed,' says Sir John Herschel, 'is said to be seen when it traverses a dark room through a hole in the shutter, or when in a partially clouded sky luminous bands or rays are observed as if darted through openings in the clouds, diverging from the (unseen) place of the sun as the vanishing point of their parallel lines seen in perspective. But the thing seen in such cases is not the light, but the innumerable particles of floating dust or smoky vapor, which catch and reflect a small portion of it, as when in a thick fog the bull'seye of a lanthorn seems to throw out a broad, diverging luminous cone, consisting in reality of the whole illuminated portion of the fog.' (pp. 223-4.)

The rectilinear transmission of light is also proved by the phenomena here mentioned by Sir John, as well as by observations too familiar to need recital. We ascertain the rapidity of its transmission from more abstruse considerations. Ordinary terrestrial phenomena indicate that the communication of light is instantaueous, and for what we name 'practical purposes' this is so. As a fact, however, it requires time and is subject to a definite velocity.

Around the planet Jupiter, four satellites revolve in different. orbits, nearly circular. The periodical times of their revolutions, as well as the dimensions and positions of both the satellites and their orbits, have been carefully and accurately determined. The three nearest to the planet move in orbits lying nearly in the plane of the path of the latter round the sun. Consequently, they suffer eclipse by the interposition of the body of the planet at every revolution. The observation of these eclipses being useful in the determination of longitudes of places on the earth's surface, the periods of their occurrence are now regularly calculated beforehand. But the times thus predicted,

upon data so thoroughly ascertained, were found to vary from the observed times, being some times earlier, some times later, by a regular gradation of differences. In 1676, Roemer, a Danish astronomer, traced these discrepancies to their true cause. The eclipses took place too soon at the periods when the earth in its annual course came nearest to Jupiter, too late when it receded farthest. The total variation, amounting to sixteen minutes and twenty-six seconds, or not quite one thousand seconds, indicated, therefore, the time consumed by the light from the satellites in crossing the diameter of the earth's orbit. This diameter, heretofore taken at one hundred and ninety millions of miles, is now considered (from late observations upon the distance between the orbits of Mars and the earth) as more probably being about one hundred and eighty-four millions of miles in length. From these data the velocity of light appears to be about one hundred and eighty-six thousand, five hundred miles per second.

The discovery of the aberration of light by Dr. Bradley, in 1727, afforded a means of confirming this almost incredible result. Though we can not here enter upon a full explanation of this phenomenon, a conception of it may be had by considering the case of two men moving with rapidity in opposite directions during a shower of rain falling perpendicularly. The rain-drops will fall upon the faces of the two men as if proceeding in inclined lines from points in front of their respective zeniths. The rain-drops represent the rays of light in the astronomical phenomenon, and the opposing motions of the observer are those of the earth at the opposite sides of its orbit. The inclination of the rays is the result of the motion of light combined with the earth's orbital movement. The latter is known and the angle of inclination can be measured, and these data furnish, by an extremely simple. calculation, an estimate of the velocity of light.

But the velocity of light has also been measured by means of mechanism, the principle of whose action may be said to be the subdivision of a second of time into very minute parts,- in a word, the atomizing of time. M. Fizeau, of the French Academy of Sciences, effected this by means of a toothed wheel, in which the teeth were precisely of the same size as the intervals between them. The light of a lamp was directed through an