or recede, as the separating forces are overcome, cease to act, or acquire force. They cannot altogether part company because, besides the repulsive, there is an attractive force; and the position of equilibrium is that point at which attraction and repulsion are equal to one another. Take a glass tube filled with sulphurous acid gas, place it in a dark room, send through it a powerful beam of light; the vessel seems empty as a vacuum, but soon a beautiful sky-blue colour is seen along the track of the beam. Various other colourless substances, of the most different properties, optical and chemical, may be experimented upon to produce the blue of the sky, luminous clouds, and splendid iridescences. These colours are produced by the shining of light upon matter. Space, traversed by rays from all suns and stars, is itself unseen; and the æther which fills that space, and by its motions lights up the universe, is invisible. "Colour depends solely upon the rate of the oscillations of the particles of the luminous body, red light being produced by one rate, blue light by a much quicker rate, and the colours between red and blue by the intermediate rates."1 Take a tube containing air and amyl vapour. They are both invisible. Converge the rays of an electric lamp to a focus in the middle of the tube. For an instant it is dark, but quickly the beam darts through a luminous white cloud, the molecules of the nitrite of amyl are shaken asunder, there is a shower of liquid particles, and the flash is like "a solid luminous spear." This separation, or breaking up, is effected by exciting differential motions among the atoms, and the motions are introduced by the shock of the waves from the lamp. The waves most effectual in shaking asunder compound molecules are not the red and the ultra-red, but those of least mechanical power, the violet and ultra-violet. They are probably millions of times less than the ultra-red waves, yet the great are powerless and the less are potent. Sky-matter, or matter in the skyey condition, which we are now acquainted with, the basis of light, consists of particles so infinitesimal that the bewildering vastness of the distances in stellar space has here to be reversed; by no possible exertion of our present faculties can we picture 1 "Chemical Rays and the Structure and Light of the Sky:" Prof. Tyndall. Action of the Firmament. 163 the ultimate atom. Sir John Herschel calculated that the matter composing the tail of a comet 100,000,000 of miles in length and 50,000 miles in diameter, would do little more than fill a wheel-barrow; and, as to all the matter in our firmament, Professor Tyndall says, "I have sometimes thought that a lady's portmanteau would contain it all. I have thought that even a gentleman's portmanteau-possibly his snuff-box -might take it in." Æther-waves untie the bond of chemical affinity by striking against and breaking up gaseous and other molecules; in some cases yield up their motion to these molecules, in others glide round them, or pass through the inter-molecular spaces without apparent hindrance. Those waves of æther are copiously absorbed which synchronise with the periods of the molecules amongst which they pass, and those are most copiously transmitted which do not synchronise. Transparency is due to inability to absorb luminous rays. Snow and ice are not dissolved by sunshine, but by the warm dark rays which are not luminous at all. The elementary gases, oxygen, hydrogen, nitrogen, and the mixture of atmospheric air, are practical vacua to the waves of heat. The experiments on permanent gases have been extended to the vapours of volatile liquids, which also possess different powers of intercepting calorific rays. Perfumes, diffused in the air, though their attenuation is almost infinite, produce a similar effect. Patchouli scent takes up thirty times the quantity of heat intercepted by the atmospheric air which carries it. Patchouli acts more feebly on radiant heat than does any other perfume yet examined. These perfumes of Scripture absorb most: cassia, 109 times; spikenard, 355; aniseed, 372. The vapour of water is the most powerful absorber of radiant heat hitherto discovered. This vapour is almost infinitesimal in amount, 99% out of every 100 parts of the atmosphere consisting of oxygen and nitrogen; yet this vapour exerts from 100 to 200 times the action of the whole body of air, and is of the utmost consequence to the life of the world. It takes up the heat waves, becomes warm, and then enwraps the earth as with a garment to maintain warmth, and, at same time, to exclude scorching heat. Earth-rays not being of power equal to those of the sun, are unable to pierce this vapour and escape into space, so that, in consequence of this difference in action, the mean temperature of our planet is higher than is due to its distance from the sun. That is not all. The waves of æther, acting upon the molecules of matter in the firmament, break them up by giving their own motions to the component atoms,-that is these atoms, or some of them, begin to synchronise with the vibrations of the infringing æther, and the rates of motion being made to vary, the molecules are decomposed. By this operation, carbonic acid gas, contained in the air, is fitted to become food for the vegetable world. The leaves of plants absorb the gas, and when in the leaves, the incipient loosening of the molecules by the action of light enables the leaf to seize upon and appropriate the carbon, while the oxygen is discharged into the atmosphere. Leaving out details as to the polarisation of light, it is evident that the firmament contains a marvellous and harmonious cooperation of phenomena, but of so vast a nature that we cannot unravel the whole mystery. Because we cannot unravel the mystery and how should we, seeing that creative design, if there is design, must extend to the whole of nature—our assertion that wherever we find marks of purpose and contrivance, there must be corresponding will and design, is met by the humorous reply, "If there be pepper in the soup, there must be pepper in the cook who made it, since otherwise the pepper would be without a cause." Mr Mill was, we think, the author of this combination of salt, pepper, and soup, to puzzle our intellectual co-ordination of experiences. When, by a play upon words, we are required to assume that God must be partly of iron and partly of clay, seeing that they are in the universe; otherwise we have no right to say, "the Supreme is wise," because there are marks of will and contrivance in the world; the ingenuity of our opponents must be pushed to the furthest limits. Surely motion is a manifestation of energy; the causes of visible appearances are not the appearances themselves; nor is law an agent or agency by which substances are coerced, but an abstract expression of the series of positions which substances assume under given conditions. We are willing to interpret law as the order of sequence. In so doing Memorial of the Supreme. 165 we refuse to allow that the Eternal Power, of whom the web of phenomena is a visible garment, is to be degraded into a necessary order, or fate, or a physical property, or mere strand in the web of phenomena. He is the Infinite and Inscrutable God; not an intelligence circumscribed, adapting its own internal processes to other processes going on externally; but a Spirit to whom we as correctly attribute the wisdom as we do the energy displayed in the universe. The arguments generally used to divest the Infinite and Eternal of wisdom and will, do, when applied in a like manner, unclothe all human conduct from volition and intelligence. For example, take the President of the British Association, assembled at Belfast in the year 1874, as a reasonable being. Why? For no other reason, though some doubt, than that he behaved as if he were reasonable. The president of 1874 used the playful illustration in reference to the president of 1870. Even suppose, taking his address, we cannot go further than the as if, still, there is no other known method of accounting for his conduct than by saying, he had some portion of intelligence. "Hold thou the good, define it well, For fear divine philosophy Should push beyond her mark and be In Memoriam. If a man is insensible to the mystery of the universe; if the soul is that of an animal-unvisited by gleams of any brighter life, dead to the stirring sacred impulses of piety-how can we make him feel that of which his nature is incapable? Happily, no such man exists; and only men of souls most shrivelled, with narrow vision of life's realities and the world's vastness, can entertain the notion that our human organism is limited to the material mechanism. Encompassed by mysteries, subjected to influences of awe, tenderness, sympathy, which no words can express, no theories fully explain, with moral and æsthetic instincts, inclining us to the good, the pure, the beautiful; visited with convictions that there is a larger life than the visible firmament contains; and all these physically exhibiting themselves in actions and reactions of the organism, we are compelled to regard them as memorials of the Supreme, and tokens that we are centres to which the intelligible universe converges, and from which it radiates. As we advance in science, the world enlarges with our knowledge; shall we, instead of growing with the world, allow an atheistic system to separate us from the universal existence by a quibbling statement-" There is no bridge," and thus lose our good portion in that glorious world which is deeper and higher than all phenomena? Are we to stop as men already at the finality of existence, though always having fresh experiences? Were it not better to hope that we shall, ere long, possess the keys which unlock mysteries, and reveal what is and will be? If a man say-"We have no organs for apprehension of the Supernatural," must we think that the Supernatural is incapable of manifesting Himself within us; and if we cannot think of an effect without a cause, or of creation without a creator, is not that a manifestation? If we cannot obtain from matter anything that was not contained in the original atom, though Godhead is revealed in a world of beauty, do we not rightly regard our intellectual and moral nature, those germs of goodness which enabled prophets and apostles to become so great, as revelations of the supernatural, a kind of bridge, so that we have experiences of Divinity, in the faithful use of which holy men do, indeed, as by a change of position, bring into view and within the circle of spiritual knowledge that which before was unknown? |