A History of Science — Volume 5

by Henry Smith Williams; Edward Huntington Williams

Now the point of the recent observations is that the fluctuations in the sun's heat, due to the periodic increase and subsidence of sun-spot disturbances—such fluctuations having been long recognized as having regular cyclic intervals of about eleven years—are instrumental in effecting changes in the terrestrial weather. According to the paper just mentioned, it would appear to be demonstrated that the periods of decreased rainfall in India have a direct and relatively unvarying relationship to the prevalence of the sun-spots, and that, therefore, it has now become possible, within reasonable limits, to predict some years in advance the times of famine in India. So important a conclusion as this is certainly not to be passed over lightly, and all the world, scientific and unscientific alike, will certainly watch with acute interest for the verification of this seemingly startling practical result of so occult a science as solar spectroscopy.

The theory of the decomposition of the elements is closely bound up with the meteoritic theory. In a word, it may be said of each that Professor Lockyer is firmly convinced that all the evidence that has accumulated in recent years is so strongly in favor as to bring these theories almost to a demonstration. The essence of the meteoritic theory, it will be recalled, is that all stars have their origin in nebulae which consist essentially of clouds of relatively small meteorites. It will be recalled further that Professor Lockyer long ago pointed out that stars pass through a regular series of changes as to temperature, with corresponding changes of structure, becoming for a time hotter and hotter until a maximum is reached, and then passing through gradual stages of cooling until their light dies out altogether. Very recently Professor Lockyer has been enabled, through utilization of the multiform records accumulated during years of study, to define the various typical stages of the sidereal evolution; and not merely to define them but to illustrate them practically by citing stars which belong to each of these stages, and to give them yet clearer definition by naming the various elements which the spectroscope reveals as present in each.

His studies have shown that the elements do not always give the same spectrum under all conditions; a result quite at variance with the earlier ideas on the subject. Even in the terrestrial laboratory it is possible to subject various metals, including iron, to temperatures attained with the electric spark at which the spectrum becomes different from that, for example, which was attained with the lower temperature of the electric arc. Through these studies so-called series-spectra have been attained for various elements, and a comparison of these series-spectra with the spectra of various stars has led to the conclusion that many of the unknown lines previously traced in the spectra of such stars are due to the decomposition products of familiar elements; all of which, of course, is directly in line of proof of the dissociation hypothesis.

Another important result of Professor Lockyer's very recent studies has come about through observation of the sun in eclipse. A very interesting point at issue all along has been the question as to what layers of the sun's atmosphere are efficient in producing the so-called reverse lines of the spectrum. It is now shown that the effect is not produced, as formerly supposed, by the layers of the atmosphere lying just above the region which Professor Lockyer long ago named the chromosphere, but by the gases of higher regions. Reasoning from analogy, it may be supposed that a corresponding layer of the atmosphere of other stars is the one which gives us the reverse spectrum of those stars. The exact composition of this layer of the sidereal atmosphere must, of course, vary with the temperature of the different stars, but in no case can we expect to receive from the spectroscope a full record of all the substances that may be present in other layers of the atmosphere or in the body of the star itself. Thus, for example, the ordinary Freuenhofer spectrum of the sun shows us no trace of the element helium, though through other observations at the time of eclipse Professor Lockyer had discovered that element there, as we have seen, some thirty years before anything was known of it on the earth.

In a recent eclipse photographs were taken of the spectra of the lower part of the sun's atmosphere by itself, and it was found that the spectrum of this restricted area taken by itself gave the lines which specialize the spectra of so different a star as Procyon. "I recognize in the result," says Professor Lockyer, "a veritable Rosetta Stone which will enable us to read the celestial hieroglyphics presented to us in stellar spectra, and help us to study the spectra and to get at results much more distinctly and certainly than ever before."

But the most striking confirmation which the meteoritic hypothesis has received has come to hand through study of the spectrum of the new star which appeared in the constellation Perseus in February, 1901, and which was so widely heralded everywhere in the public press. This star was discovered on the morning of February 22d by star-gazers in Scotland, and in America almost simultaneously. It had certainly not been visible a few hours before, and it had blazed up suddenly to a greater brilliancy than that of a first-magnitude star. At first it was bluish-white in color, indicating an extremely high temperature, but it rapidly subsided in brilliancy and assumed a red color as it cooled, passing thus, in the course of a few days, through stages for which ordinary stars require periods of many millions of years.

The most interesting feature of the spectrum of this new star was the fact that it showed both light and dark lines for the same substances, the two lying somewhat apart. This means, being interpreted, that some portions of a given substance are giving out light, thus producing the bright lines of the spectrum, and that other portions of the same substance are stopping certain rays of transmitted light, thus producing the dark lines. The space between the bright and dark lines, being measured, indicated that there was a differential motion between the two portions of substance thus recorded of something like seven hundred miles a second. This means, according to theory—and it seems hardly possible to explain it otherwise—that two sidereal masses, one at least of which was moving at an enormous rate of speed, had collided, such collision, of course, being the cause of the incandescence that made the mass suddenly visible from the earth as a new star.

New stars are by no means every-day affairs, there having been but thirty-two of them recorded in the world's history, and of these only two have exceeded the present one in brilliancy. As a mere spectacle, therefore, this new star was of great interest; but a far greater importance attaches to it through the fact that it conforms so admirably to the course that meteoritic hypothesis would predict for it. "That is what confounds my opponents," said Professor Lockyer, in talking to me about the new star. "Most of those who oppose my theory have not taken the trouble to make observations for themselves, but have contented themselves with falling back apparently on the postulate that because a theory is new it must be wrong. Then, outside the scientific world, comparatively few people appreciate the extreme parsimony of nature. They expect, therefore, that when such a phenomenon as the appearance of a new star occurs, the new-comer will establish new rules for itself and bring chaos into the scientific world. But in point of fact nature never does things in two ways if she can possibly do them in one, and the most striking thing about the new stars is that all the phenomena they present conform so admirably to the laws built up through observation of the old familiar stars. As to our particular theories, we here at South Kensington"—it will be understood that this use of the editorial "we" is merely a modest subterfuge on the part of Professor Lockyer—"have no regard for them at all simply as ours. Like all scientists worthy the name, we seek only the truth, and should new facts come along that seem to antagonize our theory we should welcome them as eagerly as we welcome all new facts of whatever bearing. But the truth is that no such new facts have appeared in all these years, but that, on the contrary, the meteoritic hypothesis has received ever-increasing support from most unexpected sources, from none more brilliantly or more convincingly than from this new star in Perseus." And I suspect that as much as this at least—if not indeed a good deal more—will be freely admitted by every candid investigator of Sir Norman Lockyer's theory.

SIR WILLIAM RAMSAY AND THE NEW GASES

The seat of Sir William Ramsay's labors is the University College, London. The college building itself, which is located on Gower Street, is, like the British Museum, reminiscent or rather frankly duplicatory in its columned architecture of the classical. Interiorly it is like so many other European institutions in its relative simplicity of equipment. One finds, for example, Professor Ramsay and Dr. Travers generating the hydrogen for their wonderful experiments in an old beer-cask. Professor Ramsay himself is a tall, rather spare man, just entering the gray stage of life, with the earnest visage of the scholar, the keen, piercing eye of the investigator—yet not without a twinkle that justifies the lineage of the "canny Scot." He is approachable, affable, genial, full of enthusiasm for his work, yet not taking it with such undue seriousness as to rob him of human interest—in a word, the type of a man of science as one would picture him in imagination, and would hope, with confident expectation, to find him in reality.