Skillful spectroscopists succeeded in detecting and delineating the lines that were peculiar to each substance. By burning such substances in flame, they were able to produce the lines, and thus verify results. By such experimentation the various lines present in the solar spectrum were separated from the complex result, and the conclusion was reached that in the burning surface of the sun certain substances well known on earth are present; for the lines of those substances are shown in the spectrum.
No other known substances would produce the given lines. The conclusion is overwhelming that the substances in question are present in a gaseous condition in the burning flames of the sun. Down to the present time the examination of the sun's atmosphere has shown the existence therein of thirty-six known elements. These include sodium, potassium, calcium, magnesium, iron, copper, cobalt, silver, lead, tin, zinc, titanium, aluminium, chromium, silicon, carbon, hydrogen and several others.
It was thus established that in the constitution of the sun many of the well-known elements of the earth are present. There could be no mistake about it. An identity of lines in such a case proved beyond dispute the identity of the substance from which such lines are derived. The existence of common materials in the central sphere of our system and in one of his attendant orbs—our own—could not be doubted. The discovery of such a fact led by immediate inference to the expectation and belief that the other planets were of like constitution, or in a word, that the whole solar system was essentially composed of identical materials.
As the inquiry proceeded, it was found, however, that the agreement in the lines of different spectra was not perfect. Lines would be found in the spectrum derived from one source that were not present in a spectrum derived from another source. Materials were therefore suggested as present in one body that were not present in another. Still further inquiry confirmed the belief that while there is a general uniformity in the materials of our solar system, the identity is not complete in all. An element is found in one part that may not be found in another. Hydrogen shows its line in the spectrum derived from every heavenly body that has been investigated; but not so aluminium or cobalt. Sodium, that is, the salt-producing base, is discovered everywhere, but not nickel or arsenium. The result, in a word, shows a certain variability in the distribution of solar and planetary matter, but a general identity of most.
The question next presented itself as to the character of the luminous bodies beyond the solar system. Of what kind of matter are the comets? Of what kind are the fixed stars? Of what kind are the nebulæ? Could the spectroscope be used in determining also the character of the materials in those orbs that we see shining in the depths of space? The instrument was turned in answer to these questions to the sidereal heavens. No other branch of science has been prosecuted in the after half of this century with more zeal and success than has the spectroscopic analysis of the fixed stars. These are known by the telescope to have the character of suns. The most general fact of the visible heavens is the plentiful distribution of suns. They sparkle everywhere as the so-called fixed stars. To them the telescope has been virtually turned in vain. We say in vain because no single fixed star has, we believe, ever been made by aid of the telescope to show a disc.
On turning the telescope to a fixed star, its brightness, its brilliancy, increases according to the power of the instrument. Coming into the field of one of these great suns of space, the telescope shows a miraculous dawn spreading and blazing into a glorious sunrise, and a sun itself flaming like infinite majesty on the sight; but there is no disc—nothing but a blaze of glory. Thus in a sense the telescope has worked in vain on the visible heavens. But not so the spectroscope. The latter has done its glorious work. Turning to a given fixed star, it shows that the tremendous combustion going on therein is virtually the same as that in our own sun. There, too, is flaming hydrogen, and there is carbon and oxygen and iron and sodium and potassium and many other of the leading elements of what we thus know to be universal nature. The suns are all akin; they are cousins-german. They are of the same family—they and their progeny. They were born of the same universal fact. They are of the same Father! They are builded on the same plan, and they have a common destiny. Aye, more, the nebulæ that float far off, swanlike, in the infinitudes, are of the same family. The nebulæ may be regarded as the mothers of universes. It is out of their bosoms that the life and substance of all suns and worlds are drawn! And these, too, are composed of the common matter of universal nature. It is the same matter that we eat and drink. It is the same that we breathe. It is the same that we see aflame in our lamps and grates. It is the same that is borne to us in the fragrance of flowers planted on the graves of our dead. It is the common hydrogen and carbon and oxygen and nitrogen of our earth and its envelope. It is the soda of our bread; the potassa of our ashes; the phosphorus of our bones and brain! Indeed, the universe throughout is of one form and one substance, and there is one Father over all. Sooner or later the concepts of science and of religion will come together; and the small agitations and conflicts of human thought and hope will pass away in a sublime unity of human faith.