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The sailor-savant Scoresby, 1817, tells us more at length of what he saw. That discoloured water forms about onequarter of the sea between 74° to 80° north latitude, and is often in bands or streams of very variable dimensions, which lie more or less north and south. In that year, at the parallel of 74° N., from 12° to 0° E. (200 miles), the water was blue and transparent, then grass-green and opaque, sometimes progressively, sometimes so suddenly that the line of separation was like the rippling of a current, the two waters keeping quite distinct from each other.

In 68° N. and 12° W., he found brown water; rather higher up grass-green, with a shade of black.

Dr. R. Brown, who has frequently visited these seas, found the Greenland seas vary from ultramarine to olive, from transparency to dark opacity, and these changes were persistent, not transitory phenomena. In a few hours he has passed through patches of deep black, green, and skyblue, the water, too, being sometimes so opaque that tongues of ice and other objects could not be seen at the depth of a few feet. Nordenskiöld says that in these seas a ship may sail with the one side in blue, the other in grey-green water. At Spitzbergen there are two usual colours, indigoblue and grey-green; in the Greenland seas, brown also. Koldeway corroborates this.

The colour of "the black waters" has been ascribed to the presence of organisms on which the right-whale feeds. Scoresby thought the medusoid the chief form; Brown found associated with this the crustacean (various entomostraca, as Cœtochilus, &c.), and molluscs (as in the pteropod form, Clio Borealis). The whalemen rejoice to find this dark water, which is so full of these organisms sometimes (he notices one evening in particular), that a few minutes sufficed to catch a pint measureful of them and other forms in the net. This was when the temperature was 32′ 5′′ Fahr.

Next morning, position and other circumstances being the same, but the temperature of the sea at 27' 5" Fahr., no ice at hand, in half-an-hour not one specimen was caught.

But though they had disappeared, the sea kept the same tint, and in the water abundant forms of diatoms were found. The alimentary canals of the "whale's food" were found full of them also.

The most prominent form of diatom is a melosira (M. Arctica). It looks like a delicate beaded necklace, in diameter about of an inch, in length of "beads" or s of an inch. The colour of the beads (cells) dark browngreen; the necklace might grow to the length of one-tenth of an inch. These diatoms grow and accumulate under the floe-ice to such an extent, that when it breaks up in early spring the brown slimy bands thus formed on the surface of the water have been mistaken for Laminaria, a kelp-weed; also, deep down, say two hundred fathoms, very few of these organisms have been found.

So it would appear that these colours are due not so much to animal as to vegetable life, as we have seen to be the case in other parts of the ocean.

As biological facts, few are stranger than the diatom which stains the broad frozen sea, affording pasture to myriads of forms which are the sole sustenance of

"Leviathan,

Hugest of living creatures, on the deep
Stretched like a promontory;"

and thus completing the wonderful cycle of life.

For a full account of the various diatoms which stain this sea-water, I refer you to the Arctic Manual of the Royal Society, p. 319.

There are also some other streaks of discoloured water in the Arctic, but merely local and accidental, known to whalers

by various and not euphonious names. These, also, are wholly due to diatoms.

ANTARCTIC.

On my first passage round Cape Horn, I every day, gale or no gale (and we had our full share of them), examined the sea-water, which I never found blue, but it swarmed with various forms of diatoms. Unfortunately, my sketches and note-book of these things have gone some years ago, so I cannot show you their likenesses. I have not been further than 64° S.

MILKY-WAY SEA.

It was on New Year's Day, 1851, in 39° S., 55° W., I passed, in the ship of the late Admiral of the Fleet, Sir F. Moresby, through a milky-way in the sea.

It was a breezy evening, the wind from the N.W., and enough to let the ship go about nine or ten miles an hour, when, as evening fell, we noticed that the sea glimmered, and this increased as the sky darkened, till it seemed as if we were in a cream sea. I went on the bowsprit, and put my towing net overboard, and finding that in a few minutes I had enough material caught to enable me to judge of the cause, I had leisure to examine the weird effect produced by this sea. I went farther out on the bowsprit, and saw that the ship was rushing through living white water, the ripple from the bows being rather more vivid than the rest; and when a break took place on the top of the swell, the same effect occurred. The sky was as dark as pitch, hardly a star to be seen. The Southern Cross, which so many have raved about, was dimmed to insignificance. The whole of the rigging, sails, and spars of the ship stood out against the gloom like a phantom ship; it gave me the idea of the sea being the sky and the sky the sea-very

beautiful but very ghastly. I do not know how long this continued.

On examining the water, I found the appearance to be owing to Peridinia; Tripos seemed to predominate. Of course there were other forms of diatom, but few other organisms, so few as not to vitiate the conclusion that Peridinium was the "lamplighter."

Specimens and drawings, which I took at the time, were sent to the Admiralty, and to Dr. Acland, at Oxford.

I saw this appearance, near the same parallel, once again, but whether as a second appearance, or whether not so bright as on the first occasion, it had not the same spell on my imagination. An observer saw nearly the same off the west coast of Sumatra; his description of it is given in "Maury," p. 284, but it does not seem due to the same cause.

Major S. Owen, in his account of the surface fauna of the ocean, notices that, having fallen in with shoals of entomostraca, the contents of his towing net seemed like liquid fire when emptied on the deck. This was in the Bay of Bengal, but he does not say the general look of the sea was such as I have tried to describe.

THE SEA UNDER AURORA.

I will not trespass further on your time than by adverting to another accidental colour of the sea-that caused by Aurora. One account is given by Maury; of it I give a short extract. It was in a mid-winter gale off Cape Horn, a heavy sea running; the heavens pitch dark, not a star to be seen. The murkiness began to change, till the sky seemed living fire, casting a glow on the ship. The sea, too, seemed vermilion, as the waves dashed in crimson torrents over the ship; sails, spars and all put on the same hue, as if in a terrible conflagration.

"Taken altogether," says the narrator, "the howling of

the wind, the furious squalls of hail driving over and falling to leeward in ruddy showers, the mad plunging of the ship into the crimson sea, and the awful sublimity of the heavens, across which the auroral light darted in spiral streaks with meteoric brilliancy, caused a scene surpassing the wildest fancy-words fail to give a just idea of the spectacle.”

I have, more than once, seen the sea under Aurora, but not in so awe-inspiring a manner; yet the effects of the light, both on sea and ship, were equally evident and weird.

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