he wrote lately to a friend, like Saul, to seek my father's asses, and lo! I discovered a kingdom.'

As he continued his observations he noticed that the spots were becoming daily less numerous, while those which were to be seen were smaller than of yore. This continued until, at length, the Sun's face became wholly clear of spots. Schwabe, however, did not relax his observations on this account. Day after day he examined the unstained face of the Sun, until at length spots again began to make their appearance. He watched them as they daily became larger and more numerous. At length there were as many as when he first began his observations. Then they became even more numerous, attained a maximum of frequency, and then began slowly to diminish.

He saw that there was a law in these changes, and watching continually day after day, and year after year, he detected what that law is. The Solar spots increase and diminish in frequency, in a period of rather more than ten years. The very length of this period suggests the laborious character of Herr Schwabe's investigations; but he worked through more than one of these long periods. For no less than forty-five years he continued his labours with the most unremitting perseverance, and I believe that it is only quite recently that he relinquished them even for a short time; and then it was serious illness only which forced him from his chosen work.

The law of the Solar spots is now among the most thoroughly established of all astronomical facts, so that astronomers can now tell beforehand when it is worth while to turn their telescopes towards the face of the Sun, to seek for large and well-marked spots. We are now approaching the season when spots are likely to be largest and most numerous. During the past few months many fine spots have been observed. Scarcely a day has passed, indeed, when spots, well worth studying, have not been visible on the face of the Sun. But we have not yet reached the epoch of maximum spot-frequency. From now until the end of the year 1871, the Sun will at no time be less marked (on the average) with these strange and interesting objects than he is at present; and towards the end of 1870 the spots will probably be even more numerous, and larger even, than they now are.

But Schwabe's discovery, interesting as it is, was rendered infinitely more interesting by another discovery, made nearly at the same time. By one of those singular coincidences which the history of science has so often presented to men's notice, while Schwabe was prosecuting his long series of observations on the Solar spots, General Sabine and other eminent observers were engaged in tracing out the laws by which the magnetic compass is regulated. It is well known that the magnetic needle does not point due north in England, but considerably towards the west. But perhaps many are less familiar with the fact that the needle continually changes in direction, and in inclination, and even in the force with which it seeks its position of rest. Amongst other peculiarities of the magnetic

needle is the strange one, that every day it is swayed by a minute oscillation connected with the daily motion of the Sun. It seems as though it tried to follow that luminary, the end nearest to him being always swayed slightly towards him.

This oscillation is so minute, that many would think it not worth watching. But men of science thought differently, and as we shall presently see, they thought rightly.

After long and patient watching it was found that the daily oscillation of the needle is not constant in amount. And when its changes came to be carefully watched, it was found that they are periodical. The needle sways gradually over a larger and larger daily arc, until its greatest swing is attained; after which the oscillation gradually diminishes, until it has its least extent. And so the change goes on continually, in a period somewhat exceeding ten years. It will be remembered that the sun-spot period has also this length. What if the two should be in any way associated! The idea, fanciful as it seems, occurred to men of science; and they placed the periods side by side, to see if they corresponded. It was found that the periods correspond exactly. When the sun-spots are most numerous the magnetic needle has its greatest daily disturbance, and vice versa. Could anything be more surprising, or more interesting? The tiny compass, whose motions can be checked by a single filament of a spider's web, is swayed by some law of association with the Solar spots, which represent forces compared with which the most terrible manifestations of nature's power familiar to us on earth, are as the lightest touch of an infant compared with the blows of a Goliath !

But perhaps some doubt may still remain in the reader's mind. He may question whether the mere coincidence of the two periods I have spoken of, is sufficient evidence on which to ground a theory so strange and so important. Fortunately this doubt can be removed very easily. There is other evidence of the Sun's influence upon the Earth's magnetism, evidence too, which, when combined with that already adduced, leaves no room at all for question.

In the autumn of 1859 two observers, one in London, the other in Oxford, were watching the face of the Sun. Suddenly they saw a bright spot of light make its appearance, which traversed a large arc on the Sun's face before disappearing. Now at the very instant when this bright spot of light was seen, a strange magnetic disturbance took place here on our earth. At the Kew Observatory they have a self-registering instrument for noting the nature of the magnetic changes. When all is going smoothly the index of this instrument produces a waved mark, shewing the steady waxing and waning of the magnetic action. But when the line traced out by the index, on the day in question, came to be examined, it was found that, at the moment when the two observers had seen the bright spot upon the Sun's face, the index had been suddenly jerked, so that in place of the smoothly waved line a sharply indented curve made its appearance.

But even this is not all. On the self-same day, and throughout the following night, the Earth exhibited strange signs of the intensity of the magnetic thrills which were passing through her frame. Not only were magnetic compasses in Europe disturbed, but all over the world—at least wherever magnetic changes are observed-the same action was noticed. Telegraphic communication was interrupted. In some places, where the telegraph communicates written messages, a flame of fire was seen to follow the pen of the instrument. Telegraphic offices were set on fire in Norway. And, in fact, every sign was to be noticed of the occurrence of one of those strange phenomena known as magnetic storms.

But there is yet another phenomenon which we have to associate with the Solar spots, and the events I have just recorded lead us naturally to its consideration. On the night following the occurrences related above, splendid auroras were visible in both hemispheres. A confirmation was thus given to the theory, that this beautiful phenomenon is associated with magnetic disturbances. But we have seen that magnetic action is influenced by the Sun. And thus we are led at once to the conclusion that the aurora depends in some way on the solar action. In fact, the frequency of auroras has been found to follow the same law of periodicity which we have already observed in the Solar spots, and in the magnetic disturbances.

Surely we have here one of the most interesting subjects of contemplation conceivable. That beautiful phenomenon, which has in every age attracted the admiration of mankind-the aurora, whose coloured streamers wave to and fro over the northern skies, and by a thousand changes of figure and coruscations of colour force from the most careless observer exclamations of wonder and surprise-is found not only to be a phenomenon which becomes visible simultaneously in both hemispheres of this great Earth of ours, but to be swayed by influences sent by the Sun across those millions of miles which separate us from him. Not merely do the coloured streamers visible to us sway responsive to others which are watched perchance in the Antarctic seas, but they obey an influence which doubtless affects the other planets also. So that in Venus and Mercury, so much nearer to the Sun than we are, and in distant Jupiter and Saturn, whose mass exceeds so manifold that of our Earth, the same brilliant displays are lighted up by the same solar impulses. Their frames thrill also, I doubt not, with the same magnetic influences. And thus a new bond of union and of harmony is added to those others, by which astronomers have brought the members of the Solar System into close companionship and correlation.

Let us return, however, to the Solar spots.

Amongst the other remarkable appearances presented in the neighbourhood of the spots, I must call special attention to those objects which have been named the 'solar willow-leaves.' Mr. Nasmyth, who was the first to associate this name with these strange-looking objects, depicts them as long interlacing streaks of light, particularly well marked

in the long thin bridges which extend from side to side of many spots. In the penumbra, or fringed edge of a spot, they are also well seen. Other observers, while recognizing the existence of these objects, describe them somewhat differently. Father Secchi, for instance, compares them to strokes made by a camel's hair pencil. Mr. Stone, of the Greenwich Observatory, compares them to rice-grains. Mr. Huggins, on the other hand, considers that some more general name-he suggests that of granules-should be given to them. The latter observer recognizes their existence all over the face of the Sun, but he assigns to them a much more regular form where they are not close to a spot.

It must be remembered in considering these objects, that though they appear very minute indeed, the least of them is scarcely smaller than England; so that their apparent mobility is among the most remarkable of all the phenomena which the Sun presents to our contemplation.

Although the strange objects called the Solar prominences, or coloured flames, are found not to be connected, as had been supposed, with the appearance or formation of Sun-spots, yet they afford such striking evidence of the tremendous nature of the forces which disturb the Solar surface, that I cannot pass them over without a few words of comment.

The prominences had been seen during the occurrences of Solar eclipses as rose-tinted flames, extending sometimes no less than 80,000 miles from the surface of the Sun. Great doubt had existed as to their nature, some astronomers conceiving that they are clouds, others that they are flames, while some considered that they are torrents of liquid fire, ejected from some enormous volcano.

During the great eclipse of August, 1868, these doubts were set at rest. The wonderful powers of the spectroscope at once served to tell us what is the real nature of these objects. It appeared from the character of the spectrum formed by their light (this spectrum consisting of a few bright lines in place of the rainbow-tinted streak, which forms the spectrum of a burning solid or liquid) that they are gaseous. They are, in fact, flames of hydrogen, with some other substances (whose nature has not yet been determined) also burning in them.

It would take me too long to describe here how astronomers found that they could trace out the prominences when the sun was shining in full splendour. I may mention, however, that if Janssen, a few days after the eclipse observations, was acute enough to devise the new method, our own countryman, Mr. Lockyer, had two years before suggested the same plan, and had only been prevented by unlooked-for delays from putting it in practice long before. As it was, he independently applied the method, the letter in which he announced his success having by a strange coincidence been placed in the hands of the President of the Imperial Academy at Paris only a few minutes before the receipt of the letter announcing Janssen's discovery of the same interesting circumstance.

And now astronomers have gone even beyond this, and are able, by

an ingenious application of the powers of the spectroscope, actually to see the prominences when the sun is shining with full splendour.

The rapid changes of figure presented by these strange protuberances, are among the most interesting subjects of solar observation. Mr. Lockyer mentions that he saw one, no less than seventy thousand miles in height, disappear completely in ten minutes!

I must not dwell further, however, on phenomena which, interesting as they are, are yet, in a sense, outside the subject of this paper.

We have seen that the history of astronomical research into the subject of the Solar spots is full of interest. We have seen how longcontinued and patient observations have at length met their reward. We begin at length to see the significance of those strange processes of disturbance, which cause the formation of the spots. And when we remember what the Sun really is to us, we see how largely we are ourselves interested in these processes. The Sun is the source of nearly every form of force existing upon the earth. The fuel which moves our engines, the vegetation which clothes our fields and nourishes our cattle, owe their inherent force to the Solar rays. Man himself owes his strength to the Sun. The acts which we perform, nay, in a sense, the very thoughts we think, consume energies which we have received from that orb, either directly or indirectly.

Those therefore among the ancients, who chose the Sun as the object of their worship, selected at least that one of God's creatures which best merits our gratitude. We, however, know that to direct that gratitude otherwise than towards Him Who made the Sun and us, is to forget the Creator in the creature. And if, by the exercise of those wonderful powers which the Almighty has given to us, we have been able to discover the laws which regulate the great luminary of the Solar System, we know that those laws also are God's creatures: He can limit or stay their action if He will; or if He will, He can abrogate them altogether.

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We should therefore be misinterpreting the lesson taught by the progress of modern science, if it did not teach us humility. We should remember what Newton said, when some one passed encomiums on his discovery of the grandest law yet revealed to man: 'It seems to me,' he answered, that I am but as a child, picking up on the sea-beach a few shells handsomer than the rest, but who is all unconscious of the wealth which lies hid beneath the waves of the wide ocean.' Let us recall also, that Laplace, on his death-bed, though he of all men knew best how many great discoveries astronomers had made, said humbly, 'What we know is little; what we know not is immense.'

If there were danger of our forgetting these lessons, of our becoming proud in our consciousness of the noble powers the Almighty has

*Before, they had only been able, as Sir John Herschel well expressed it, to become sensible of the existence of the prominences when the sun is shining; for it is one thing to see the spectrum of an object, another to see the object itself.