THE SOLAR MUTABILITY.
SCIENCE is every day teaching us to think of the Sun, and what have now been so long called the "fixed" stars, with less and less of that sense of fixity which their enormous import- ance to planetary beings would seem to render desirable. Not only have we learned that all these so-called fixed centres of
separate universes are themselves travelling in different directions (dragging their planetary systems after them) with enormous speed, though their distances from our own system are so great that, in the few centuries we have had to study them, the change has not become very apparent to ordinary perceptions ; but we have also learned that many of them are " variable " stars,—our own sun amongst the number,—becoming brighter, and again less bright at fixed intervals of years ; that some of them have broken up and disappeared some years (or perhaps thousands of years) before the blank caused by their disappearance could have struck the human retina. Nay, more, we now know that our own sun (resembling in this probably most other solar bodies of the same kind) is in so highly fluid and excitable a condition as to be constantly sending out from its surface forked tongues (thousands of miles in extent) of inflamed hydrogen gas, like the flickering streams of light from the stars of a street illumination ; and, more- over, as to be subject to great periodical disturbances, now called "magnetic storms," which are in all probability caused by certain -combinations in the movements of those little solid bodies, on one of which we live, round the sun. Even now one such epoch of magnetic storm seems to be thought pretty near at hand. The sun has been lately exhibiting the most surprising forms of dis- turbance, and presenting to scientific eyes less " fixity" of essence than ever. Spots so vast that we must estimate their dimen- sions by millions of square miles have broken out from time to time, and have presented rapid changes of figure, indicating the action of forces of inconceivable intensity. Clusters of smaller spots, extending over yet vaster areas, have exhibited every form of disturbance known to the solar physicist, and every degree of light, from the apparent blackness (in reality only relative) of the nuclei, to the intense brilliancy of the faculous ridges.
And we now know that these appearances are not merely matters for the curious, with which, as they happen at a distance of above ninety millions of miles, practical men need not concern themselves. In point of fact, it is by no means impossible that the issues of peace or war, of a financial crisis, or a religious agitation, may be closely bound up with these phenomena,—if not, indeed,—which is also quite possible,—the sudden disappear- ance of our whole system after the fashion of other solar systems which have thus disappeared. This much, at least, is certain, that the vast changes now going on in the physical constitution of the sun are changes which do most powerfully affect the electric condition of our earth, which have in former years caused the most violent disturbances in the various artificial as well as natural electric apparatuses of the world we live in, and which, to speak of the least of all its possible effects, might, just as well as not, happen some day to throw the electric condition of every telegraphic cable on our planet, under the sea or above it, into the most dire confusion, and send down Telegraphic Companies' shares to zero in a lump, even if they did not contrive to telegraph to us, after some strange inarticulate fashion, that shares in all public companies, even in that very limited public company, the human race, are, in a physical point of view, of very doubtful value indeed. Let us explain briefly to what we allude.
On September 1, 1859, shortly before noon, two astronomers,— Messrs. Hodgson and Carrington,—one at Oxford, the other in London, were at the same instant scrutinizing a large group of sun spots. On a sudden two intensely bright patches of light appeared in front of the cluster. So brilliant were they that the observers thought the darkening screens attached to their tele- scopes must have become fractured. But this was found not to be the case. The bright spots indicated some process going on upon the sun's surface,—a process of such activity that within five minutes the spots travelled over a space of nearly 34,000 miles. Now, at the Kew Observatory there are self-registering magnetic instruments which indicate the processes of change by which the subtle influences of terrestrial magnetism wax and wane. At one time the line traced by the pointer will be marked by scarcely perceptible undulations, indicating the almost quiescent state of the great terrestrial magnet. At another, well-marked waves along the line exhibit the pulsations of the magnetic system, influenced in a manner as yet unintelligible to the physicist. And then there is a third form of disturbance,—the sharp, sudden jerks of the pointer exhibiting the occurrence of those mysterious phenomena
termed "magnetic storms." When the records of the Kew Observatory came to be looked over, it was found that at the very instant in which the brilliant spots of light had appeared to Messrs. Hodgson and Carrington, the self-registering instru- ments had been subjected to the third and most significant form of disturbance,—a magnetic storm began, in fact, as the light broke out on the sun's surface. But this was not the only evidence of the sympathy with which the earth responded to the solar action. It was subsequently found that soon after the spots of light had appeared the whole frame of the earth had thrilled under a mysterious magnetic influence. At the West Indies, in South America, in Australia, wherever magnetic observations are systematically made, the observers had the same story to tell. In the telegraph stations at Washington and Philadelphia the signalmen received strong electric shocks. In Norway telegraphic machinery was set on fire. The pen of Bain's telegraph was followed by a flame. And wherever telegraphic wires were in action, well- marked indications of disturbance presented themselves. Even this, however, was not all. The great magnetic storm was not a mere instantaneous electric throe. Hours passed before the disturbed earth resumed its ordinary state. And thus it happened that in nearly all parts of the earth night fell while the storm was yet in progress. During that night magnificent auroras spread their waving streamers over the sky, both in the northern and the southern hemisphere. As the disturbed needle vibrated, the coloured streamers waved responsive, and it was only when the magnetic storm was subsiding that the auroral lights faded from the heavens.
Now, it is evident that these phenomena show the most intimate relation between these peculiar disturbances in the sun and the magnetic currents of our own earth. Directly one of these changes takes place upwards of ninety millions of miles away, the electric condition of our planet is changed in some mysterious way, of which our instruments, and even the condition of our sky, bear record. The pens of all our telegraphic wires may some day trace in flame a handwriting more ominous of human destiny, than was the handwriting which during Belshazzar's feast traced a warning on the wall of the fall of the Babylonian dynasty. Moreover, note this, that these changes in. the condition of the sun take place at intervals of about eleven years. The variable star which swings us round it, as well as supplying us with light and heat and (apparently) magnetism, clouds over every eleven years with these spots, so that it seems most likely that every eleven years certain magnetic conditions recur which have not occurred in the interval. If so, perhaps, the magnetic excitement of 1859 will recur, and it may be in much greater force next year,—in 1870. And if it does, how are we to say what may or may not recur with it? It is quite possible that those periods of speculative financial excitement—which are also said to follow a periodic law of some- thing very like the same period—may be more or less dependent on the magnetic condition of our planet, that so mean a phenomenon as speculative frenzy on the various stock exchanges of Europe may be more or less connected with these wonderful discharges of voltaic batteries in the sun. Is itquite impossible that the electric political condition of Europe in 1848, —and again at an interval of eleven years, in the year of Italian revival and revolution, 1859,—may not recur after one more period of eleven years, in 1870, in consequence of the returning epoch of magnetic excitement in the sun ? It would be ridiculous to affirm that there could be no connection between the moral excitability of nations and electric phenomena on so grand a scale as this : nor would it in any degree be a grossly materialistic explanation of moral and spiritual changes, any more than it is a materialistic explanation of moral and spiritual changes, to say that starving people are deficient in moral spirit, and that a storm of rain depresses the most gallant army that ever fought. Could we really establish any periodic law of electric excitement on the earth, it would not be irrational, but in the highest degree rational, to expect marked human pheno- mena in connection with it,—either a great concurrent depression or a great concurrent stimulus to the energies of the human brain.
But after all, what strikes our imagination most is the curious insight we are beginning to glean of the highly susceptible and sensitive constitution of the sun. That a mass but little denser, even as a whole, than water, nearly four times as light, bulk for bulk, as that of our own earth, and surrounded by an envelope of burning gas, which is by comparison with the intense heat and light of the proper surface of the sun itself mere cold and darkness,—that a mere wandering flame of this kind, shoot- ing rapidly through space, an iron-smelting furnace throwing out tongues of fire on all sides, and so highly susceptible to external influence that certain combinations of planets which, when all thrown into the same scale, would make up only an infinitesimal portion of the sun's mass, cause the most marvellous disturbances in his physical constitution and lead to magnetic storms such as we have described on his surface,—that such a body as this, we say, should yet for thousands of years exercise so orderly, continuous, and consistent an influence over the development of our terrestrial world and our human affairs, does seem truly marvellous. Can anything be conceived less apparently likely to lead to fixity of tenure in our universe than a centre for it such as this,—a great boiling furnace of forces enveloped in an at- mosphere of flaming gas, and subject to the mo't violent superficial excitements under the most apparently insignificant external influ- ences? The old Hebrew conception of an earth "founded on the seas and established on the floods," which had been made so fast that it "could not be moved," was a conception of perfect solidity com- pared to that heliocentric basis of our universe,—a hurricane of Same the disturbances of which might perhaps be best represented to our imaginations by the occasional explosion of a planet or two of nitro-glyeerine,—which we are compelled to substitute. Yet hence proceed attractions of gravitation which have not .sensibly altered during the life of man upon the earth,—waves of light indicating by their spectra the burning of the very same sub- substances in the sun as were being consumed in all probability when the words 'let light be' were first registered,—and, as we now -appear likely to learn, periodic magnetic impulses, recurring with the punctuality of seasons and eclipses, certain to be full of im- port for us, and yet not improbably of the same nature as those greater hurricanes by which other suns have perished. Is it possible to conceive a more apparently unstable centre and fountain of a universe of law and order ? Is it possible to con- ceive a more impressive lesson on the words, "He maketh His ministers a flaming fire " ?
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