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into one more fortunate in its antecedents, far above it physically, morally, intellectually. The process may be described as extinction, as ceasing to be. But it is at any rate a euthanasia. It is a death out of which life springs. The stock which, if kept separate, might have dwindled and died, and at the best. could only have gradually raised itself by slow and painful effort in the course of many centuries to an equality, or a quasiequality, with its neighbor, is carried rapidly, almost at a bound, to civilization, to refinement, to intellectual power. It ceases to exist as a separate stock; but it becomes an element in the composition of a great people. It obtains a full share of the mental and moral treasures inherited by the present from past ages. And it gives something in its turn. It contributes to the common fund of national qualities some important traits. It is a factor in the result arrived at. Whatever point of mental advancement, whatever perfection in morals and in art, whatever height of fame and earthly glory the mixed race may reach, each element-even the lowest-may claim its part in them.

As it thus appears that one and the same course of conduct is prescribed, in the matter before us, by both self-interest and benevolence, it is unnecessary to pursue any further the present investigation.

GEORGE RAWLINSON.

То

ECLIPSES OF THE SUN.

O the unaided vision the apppearance of the sun is suggestive only of calm and enduring quiescence: the first man who ever looked upon it saw in it only the same effulgent globe which we see at the present time. If every generation which has seen it could have handed down to posterity its image as it appeared to them, not the slightest trace of change could be discovered by the most careful examination; not a solitary deviation from perfect roundness of form would ever have been seen; nothing suggestive of motion or change upon its surface would ever have been noted, except perhaps at very rare intervals the appearance of a spot so minute that the eye could scarcely discern it.

We now know that this appearance of quiescence is entirely an illusion arising from our immense distance from the luminary, and that the sun is really a theatre of operations going on on a scale so stupendous as to transcend all our conceptions. Its earthquakes extend over thousands of square miles and bury its whole surface in a chasm of liquid fire; the craters of its volcanoes open widely enough to ingulf the earth, and throw up flames fifty thousand miles high; its hurricanes sometimes blow one hundred or even two hundred miles in a second, and would instantly reduce any terrestrial matter they might strike to a fiery cloud. But before we reach a distance of ninetytwo millions of miles, our earth would to the unaided vision vanish into a point too small to be visible; the sound of the convulsion, terrific though it must be on the sun, cannot penetrate the vacuum; the flames which surround it are lost in the effulgence of its surface, and thus it happens that, stupendous

though the movements are which are going on at the surface of the sun, they have been discovered only by a long and arduous series of observations.

It is perhaps not too much to say that the origin of all we really know of the physical constitution of the sun and of the extraordinary changes going on upon it is due to the occasional occurrence of total eclipses. For although the observations. made during total eclipses are not now the most important ones, although the spectroscope may reveal to us the flames surrounding the sun on any perfectly clear day, yet it is very doubtful if a hint of the mode of using the spectroscope would have been obtained had not these surroundings been exposed to view during the rare moments of total eclipses. We thus have the seeming paradox that most of what we have learned respecting the physical constitution of the sun has been gained by the hiding of it from view.

It is very curious that the apparent diameters subtended by the sun and moon are so nearly equal that a total eclipse of the sun is barely possible. Had the diameter of the moon been by a very small amount less than it is, or had the moon been placed a little further from the earth, or had the diameter of the sun been a little larger than it is, such a phenomenon would have been entirely impossible; the eclipse of the sun would have been only partial or annual, and the opportunities for studying the surroundings of the sun which total eclipses have given us would never have been enjoyed. As an introduction to what we have to say on the subject, a general account of the progress of an eclipse will not be out of place. The circumstances have first to be foretold from the astronomical tables of the sun and moon. The breadth of the dark shadow of the moon as it passes over the earth does not often exceed one hundred or one hundred and fifty miles, and it is necessary to know just where this shadow will pass in order that observers may station themselves near the centre of its path. An exaggerated estimate of the accuracy which has been obtained in this direction is often made by men of intelligence, and even by those well versed in astronomy. That the path of the shadow over the earth can be marked out at all, years beforehand, is an intellectual feat so extraordinary, that when the

possibility of doing it is once demonstrated the ordinary mind is quite ready to accept almost any idea of what can be done. Thus it is often thought that the predictions of the astronomer are so unerringly accurate that the most careful observation can show no deviation, and that the time of the eclipse can be predicted a century in advance with the accuracy of one or two seconds. Now the fact is that the time of the late eclipse as predicted was nearly one half a minute in error, while the actual path of the shadow was some ten miles from the predicted one. This does indeed show the errors of the tables of the moon, but it is an error the existence of which has for some time been known, and which we hope will be before long corrected.

The observer, having placed himself, as nearly as he can judge, where the centre of the shadow shall pass over him, looks at the appointed time for the first contact of the moon on the disc of the sun. Up to this moment not a sign of what is coming can be perceived, the sun presenting exactly the same aspect that it always does. I do not think one ever observes an eclipse for the first time without feeling a slight incredulity as to what is coming during the few seconds which precede its first appearance, but after repeated experience of the certainty with which the prediction is fulfilled this feeling wears off, and the observer looks with entire confidence that within a minute he will see a notch begin to form on the limb of the sun. He is sure to see it if he is looking at the right place, and he knows the time at which it commences.

An hour or more must now in general elapse before the sun is entirely covered. During this hour the sun is as it were gradually eaten away by the advancing moon, and is at length reduced to a thin crescent. Up to this time no remarkable change is noticeable in the light; it is indeed very curious how little the eye marks the loss even of three fourths of the ordinary light of the sun. What is first remarked is not so much the apparent approach of darkness as a singular change in the aspect of the light, which becomes of a lurid tint, as if the air were filled with smoke through which the sun was shining, or the sun itself changed to a distant fire. The reason of this appearance is that the light now comes almost entirely from near

us.

the edge of the sun. It is well known that the atmosphere. of the sun absorbs a large proportion of the blue light, and that this absorption is much greater near the edge of the sun than at its centre, owing to the greater thickness of atmosphere through which the rays of light have to pass in order to reach By simply looking through a well-smoked glass the observer can see that the edge of the sun looks darker than its centre, owing to this absorption. The central or blue part of the sun's apparent disc being entirely cut off by the moon, we can see only the reddish region near the limb. Thus the light of day as the eclipse progresses becomes more and more lurid. until the sun has almost disappeared.

At length only a minute thread of light is left, and the observer knows that the grand phenomenon is right upon him. If he is upon a lofty eminence, so as to command a view of a wide extent of country, he will see the region west of him enveloped in darkness, while toward the east the sun is still shining. During our recent eclipse the shadow of the moon passed over Pike's Peak, from the summit of which the view extended some seventy miles in every direction. The sight of the mighty shadow approaching at the rate of a mile in two seconds is described by the spectators on the mountain as one of the grandest and most impressive sights which they ever beheld.

As the shadow comes upon the observer there is a rapid increase of the darkness, as if a pall were spread over the heavens. At the same moment the small thread of sunlight which remains visible is broken up into little points of light, which disappear in rapid succession. As the last of these vanishes, a singular transformation of the scene is noticed. Unless the observer is favored by an unusually clear sky, or knows what to expect, he will not remark any thing before totality except the slowly-vanishing crescent of the sun, or the coming of darkness. But at the moment that the last ray of sunlight disappears he sees the moon as an intensely black globe, surrounded by a soft effulgence or corona. With the aid of a telescope, and very often without it, tongues of rosecolored flame are seen shooting out from behind the moon. These are the eruptions of glowing hydrogen thrown up from

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