Wondering what could be the nature of this mysterious light, I climbed into the shrouds, in order to get a better view. As I watched it, it suddenly began to lengthen out at both ends, like a rapidly spreading fire, and drew a long curtain of luminous mist around the whole northern horizon. Another similar light then appeared in the south-east, and although it was not yet connected with the first, it also seemed to be extending itself laterally, and in a moment the two luminous curtains united, forming a great semicircular band of pale, bluish-white radiance around the heavens, like a celestial equator belting a vast universe of stars. I could form, as yet, no conjecture as to the cause or nature of this strange phenomenon which looked and behaved like an aurora, but which seemed to rise out of the water. After watching it five or ten minutes, I went below to call the captain.
Hardly had I reached the foot of the companionway when the mate shouted again; "O Kennan! Come on deck quick!" and rushing hastily up I saw for the first time, in all its glorious splendour, the phosphorescence of the sea. With almost incredible swiftness, a mantle of bluish-white fire had covered nearly all the dark water north of us, and its clearly defined edge wavered and trembled for an instant, like the arch of an aurora, within half a mile of the ship. Another lightning-like flash brought it all around us, and we floated, literally, in a sea of liquid radiance. Not a single square foot of dark water could be seen, in any direction, from the maintop, and all the rigging of the ship, to the royal yards, was lighted up with a faint, unearthly, blue glare. The ocean looked like a vast plain of snow, illuminated by blue fire and overhung by heavens of almost inky blackness. The Milky Way disappeared completely in the blaze of light from the sea, and stars of the first magnitude twinkled dimly, as if half hidden by fog.
Only a moment before, the dark, still water had reflected vividly a whole hemisphere of spangled constellations, and the outlines of the ship's spars were projected as dusky shadows against the Milky Way. Now, the sea was ablaze with opaline light, and the yards and sails were painted in faint tints of blue on a background of ebony. The metamorphosis was sudden and wonderful beyond description! The polar aurora seemed to have left its home in the higher regions of the atmosphere and descended in a sheet of vivid electrical fire upon the ocean. As we stood, silent with amazement, upon the quarter-deck, this sheet of bluish flame suddenly vanished, over at least ten square miles of water, causing, by its almost instantaneous disappearance, a sensation of total blindness, and leaving the sea, for a moment, an abyss of blackness. As the pupils of our eyes, however, gradually dilated, we saw, as before, the dark shining mirror of water around the ship, while far away on the horizon rose the faint luminous appearance which had first attracted our attention, and which was evidently due to the lighting up of the haze by areas of phosphorescent water below the horizon line.
In a moment the mate shouted excitedly: "Here it comes again!" and again the great tide of fire came sweeping up around the vessel, and we floated in a sea of radiance that extended in every direction beyond the limits of vision.
As soon as I had recovered a little from the bewildered amazement into which I was thrown by the first phosphorescent flash, I observed, as closely and carefully as possible, the nature and conditions of the extraordinary phenomenon. In the first place, I satisfied myself beyond question, that the radiance was phosphorescent and not electrical, although it simulated the light of the aurora in the rapidity of its movements of translation from one area to another. When it flashed around the ship the second time, I got down close to the luminous surface and discovered that what seemed, from the deck, to be a mantle of bluish fire was, in reality, a layer of water closely packed with fine bright spangles. It looked like water in which luminous sand was constantly being stirred or churned up. The points of light were so numerous that, at a distance of ten or twelve feet, the eye failed to notice that there was any dark water in the interspaces, and received merely an impression of diffused and unbroken radiance.
In the second place, I became convinced that the myriads of microscopic organisms which pervaded the water did not light up their tiny lamps in response to a mechanical shock, such as would be produced by agitation of the medium in which they floated. There was no breeze, at any time, nor was there the faintest indication of a ripple on the glassy surface of the sea. Between the flashes of phosphorescence, the polished mirror of dark water was not blurred by so much as a breath. The sudden lighting up of myriads of infusorial lamps over vast areas of unruffled water was not due, therefore, to mechanical agitation, and must have had some other and more subtle cause. What the nature was of the impulse that stimulated whole square miles of floating protoplasm into luminous activity so suddenly as to produce the visual impression of an electric flash, I could not conjecture. The officers of the U. S. revenue cutter McCulloch observed and recorded in Bering Sea, in August, 1898, a display of phosphorescence which was almost as remarkable as the one I am trying to describe [Footnote: N.Y. Sun, Nov. 11 1899.]; but in that case the sea was rough; there were no sudden flashes of appearance and disappearance; and the excitation of the light-bearing organisms may have been due—and probably was due—to mechanical shock.
In the third place, I observed that in the intervals between the flashes, when the water was dark, all objects immersed in that water were luminous. The ship's copper was so bright that I could count every tack and seam; the rudder was lighted to its lowest pintle; and medusae, or jelly-fish, drifting past, with slow pulsations, at a depth of ten or twelve feet, looked like submerged moons. It thus appeared that protozoa floating freely in the water lighted their lamps only in response to excitation, of some sort, which affected, almost instantaneously, areas many square miles in extent; while those that were attached to, or in contact with, solid matter kept their lamps lighted all the time.
During one of the periods of illumination, which lasted several minutes, I hauled up a bucketful of the phosphorescent liquid and took it into the cabin. Nothing whatever could be seen in it by artificial light, but when the light had been removed, the inside of the bucket glowed, although the water itself remained dark.
The sea in the vicinity of the ship became phosphorescent three or four times; the sheet of fire in every case, sweeping down upon us from the north at a rate of speed that seemed to be about equal to the speed of sound-waves in air. The duration of the phosphorescence, at each separate appearance, was from a minute and a half to three or four minutes, and it vanished every time with a flash-like movement of translation to another and remoter area. The whole display, so far as we were concerned, was over in about twenty minutes; but long after the sheet of phosphorescence disappeared from the neighbourhood of the ship, we could see it lighting up the overhanging haze as it moved swiftly from place to place beyond the horizon line. At one time, there were three or four such areas of bright water north of us, but as they were below the curve of the earth's convexity we could not see them, and traced them only by the shifting belts or patches of irradiated mist.
[Illustration: Reindeer Bridle Snow Shovel]