Let us consider, for one instant, what a stupendous work it was to make and sustain the sun, which is every instant pouring off a flood of light on all sides, reaching ninety-five millions of miles, and flowing constantly at the rate of two hundred thousand miles a second; and consider, also, that this process has been in operation for at least six thousand years! This is indeed enough to overwhelm us with wonder and admiration; and yet we are only considering one source of light—the sun—while every fixed star in the firmament is another, and presents the same topic of admiration.
We might now pass from this view of the subject, to the uses of light—and remark upon the fact, that by means of it we see things. Color and form—all that constitutes the beauty of the world of vision—is revealed to us by light. The production of light—its manufacture and supply—is a stupendous thing—but yet its conception, its invention, was still more wonderful. There was a time when all was darkness. It was then that God said, “Let there be light, and there was light!” But he had an object in producing light. He intended that his creatures should see by it. How great, then, were his wisdom and goodness in designing it—how wonderful his power in producing it!
I intend, hereafter, to say something more about the philosophy of light; but my intention, at present, is to speak only of some curious particulars in relation to it. In the first place, let me tell you that there are some plants which throw out light. A gentleman observed, in the shady recesses of some of the rocks of Derbyshire, England, a brilliant gold and green light, which appeared to proceed from a fine net-work of moss, growing upon the rocks. In the coal mines near Dresden, in Germany, there are certain mosses, which are said to be abundant and luminous. They are described by a visitor as appearing in “wonderful beauty,” and he says, “The impression produced by the spectacle, I can never forget. The abundance of these plants was so great, that the roof, and the walls, and the pillars, were entirely covered with them. The beautiful light they cast around, was almost dazzling; it resembled faint moonshine, so that two persons, near each other, could readily distinguish their bodies.”
The phosphorescence of the sea presents a most remarkable spectacle. Sometimes the vessel, while ploughing her way through the billows, appears to mark out a furrow of fire. Each stroke of an oar gives rise to sparks of light, sometimes tranquil and pearly, at others brilliant and dazzling. These movable lights, too, are grouped in endless varieties; their thousand luminous points, like little stars, appearing to float on the surface; and their matter forming one vast sheet of light. At such times, the bright waves heave, roll, and break in shining foam; or large sparkling bodies, resembling the forms of fishes, pursue each other, disappearing and bursting forth anew.
Beautiful illuminations of the same kind are frequently seen at a great depth in the clear water, which in the night time becomes jet black. Often, through this dark, yet limpid medium, have voyagers amused themselves, by tracking the routes of large fishes, such as porpoises or sharks, gleaming along in lines of light beneath the abyss, itself invisible with gloom.
As Captain Tuckey passed in his voyage towards Prince’s Island, the ship seemed to be sailing on a sea of milk. In order to discover the cause of such an appearance, a bag, having its mouth distended by a hoop, was kept overboard, and, by means of it, vast numbers of small animals were collected. Among them, were a great many small sea animals, with innumerable little creatures attached to them, to which Captain Tuckey principally attributed the whitish color of the water.
Luminous marine animals, magnified.
Thirteen species of cancer were observed, not above one fourth of an inch long; eight having the shape of crabs, and five that of shrimps. Among these, some luminous creatures were discernible. When one species was examined by the microscope, in candle-light, the luminous property was observed to reside in the brain, which, when the animal was at rest, resembled a most brilliant amethyst, about the size of a large pin’s head; and from this there darted, when the animal moved, flashes of a brilliant and silvery light.
Of the number of these little creatures, of some of which a magnified representation is here annexed, some interesting statements are furnished by Captain Scoresby. “During a run of fifty leagues,” he says, “the sea was constantly of an olive-green color, remarkably tinted; but, on the afternoon of the 17th of April, it changed to transparent blue. This green appearance of the sea in these latitudes, was occasioned by myriads of small marine animals. A calculation of the number of these animals, in the space of two miles square, and two hundred and fifty fathoms deep, gave an amount of 23,888,000,000,000!