Popular Science Monthly/Volume 35/September 1889/Arctic Ice and its Navigation
|ARCTIC ICE AND ITS NAVIGATION.|
By ALBERT A. ACKERMAN,
ENSIGN, UNITED STATES NAVY.
FEW people can understand the fascination of summer life in the arctic regions for those who have once gone through the experience without disaster.
It is an awe-inspiring land. The massive, dreamy beauty of the slumbering icebergs, the sharp outlines and sheer height of the basalt coast cliffs, the mysterious expanse of the glacier, and the ceaseless motion of the ice-floes grinding and clashing together, produce upon all men emotions of awe and delight.
Elsewhere, Nature moves as well with power and grandeur, but more slowly and with much less amplitude of action; there, the changes that in a temperate climate require months take place tumultuously in a few days.
The breaking up and floating away of the ice-field, the débácle of the glaciers and disgorging of the fiords, impress man with his utter insignificance and weakness in the presence of such mighty forces. Fleets of lofty icebergs drift southward, urged on by deep under-currents, and plow their way through thinner ice, splitting, colliding, and overturning, always maintaining a certain sphinx-like dignity—majestic and mysterious. Vast out-reaching tongues of ice extend from their hidden bases, as hard as rock and as dangerous to the unwary navigator, while to leeward drifts a convoy of smaller bergs, the débris of the first—a jostling following too rough for safe companionship. Over all this glistening mass of marble white hover myriads of white gulls, and in the blue translucent caverns at the water's edge reverberate the swash of the sea and the music of cascades.
Amid such surroundings men can test themselves, where the brave have confessed fear and the hardy and strong confessed weakness; and so long as men are brave and strong, so will there be volunteers for expeditions, the northern limit of which depends alone upon the extent to which fortune favors their strength and judgment. Arctic exploration is not dependent, however, upon the vanity of adventurers; the world throngs with eager students of Nature, and from these must spring the motive which alone can lead to success. Rarely does it happen that robust health and love of adventure accompany the knowledge of generalization only acquired by years of study, and so essential in localities where there is little that is familiar and unworthy of record; to this, and not only to the disasters from which hardly an expedition has escaped, is due the fact that, notwithstanding the treasure expended in arctic exploration, so little is known and so many of the popular ideas are erroneous.
Most arctic travelers will agree in saying that careful study of all the works on the subject will form but a meager preparation for a prospective explorer. It is a new world; impressions are so strange and vivid that no fixed plan of description will suffice.
In the narrow Greenland waters each successive headland, island, or mountain stands as the mark of farthest progress and blasted hopes of brave old-time navigators. Can anything be more pathetic than the quaint log-book of that stanch old seaman. Captain John Davis, with its account of protracted struggles and final disappointment? He sailed in the time of Raleigh and Blake. Now, but a few miles beyond a black, ram-shaped cape, that he named Sanderson's Hoop, lies the Danish trading post of Upernavik, and every summer ten powerful steam whalers smash through the ice, which at this point turned back his small sailing vessels. For hundreds of years, dating back to the time of Davis and Frobisher, the art of ice navigation has been constantly improving, until now it is a very rare thing for either a Dundee whaler or a St. John sealer to meet with serious disaster while pursuing its legitimate calling.
With our own Bering Sea whalers the case is different—there are important differences between the ice encountered in Greenland waters and that north of Alaska. A description of the circumstances affecting the formation of the various kinds of berg and floe ice will make this clear.
The natural form of an iceberg is a regular prism, broken from the face of the glacier as its onward motion forces it down along the bottom of the inclosing fiord, by the buoyant action of the water. Through the tides the upward pressure of the water varies constantly, and has much to do with the production of internal strains and fissures, which form planes of cleavage parallel to the face of the glacier; one of these ultimately marks the boundary of the berg, the others are weak spots which may develop afterward. Where glaciers approach the sea at a steep grade, they move more rapidly, are subjected to greater stresses, there is less opportunity for the exhibition of the viscous property of ice at the freezing-point, débâcles occur more frequently, and the bergs are smaller and more irregular. Under such conditions the ice is full of partly cemented cracks and curved fissures, so that in a short time water-markings, ice-scorings and scratches, and the melting of snow-spots, produce the most fantastic and airy shapes. More durable than clouds, they still rival them in variety of design and change of form, as successive beauties are revealed in passing. Apparently free from all the requisitions of equilibrium, owing to the preponderance of the part submerged, bold spurs and flying arches spring from their walls, and hanging balconies ornament their crests.
In Greenland, as in the antarctic, there is either a great continent or a congeries of islands, covered with an ice-field of such gradual inclination through great distance that the movement of its face is very slow, and the débâcles and avalanches occur less frequently, so that the bergs are of enormous size and regular shape, having a height of from one to two hundred feet in the northern and three hundred feet in the southern hemisphere. The Alaskan glaciers are of comparatively small extent, the ice field of which the Muir and Davidson glaciers are spurs being only four hundred miles wide; owing to the inclination of their containing valleys, they move with great rapidity, débâcles are occurring continually; the bergs, falling into shallow water, quickly go to pieces, and the fragments which at last escape through the intricacies of fiords and archipelagoes are very small. In addition, the comparatively shallow water along the coast of Siberia prevents floe-bergs of any great size passing through Bering Strait, while a seventeen-fathom bank, north of Wrangell Island, bars the way to all rectangular bergs over twenty-three fathoms thick that have drifted across the arctic. In this way it happens that the Bering Sea whalers never see the great icebergs which play so important a part in the navigation of those in Greenland waters.
Perhaps the continual excitement in the confined waters of the latter land, and the natural desire to classify the new and mysterious with the old and commonplace, make the mind quick to see resemblances. However that may be, the bergs seem subject to some laws of form. Capitals, sphinxes, castles, and cathedrals are frequently met with, at times, whole menageries would troop past—lions couchant, mushrooms, and flowers occur in profusion—the small fragments of ice, through the washing of water and scoring of surrounding floes, showing a greater variety of forms than the large bergs.
On the east side of Melville Bay in north Greenland is a headland called, from its peculiar shape, "The Devil's Thumb." It is a remarkable column, resembling a closed hand with the thumb projecting upward, and bears stout testimony to the toughness of the granite composing it, which has withstood in this sharp outline all the disintegrating forces of that climate for centuries. It is about seven hundred feet high. In June, 1884, a photograph was taken of a very lofty iceberg, grounded in its vicinity, which was an almost perfect representation of a hand and wrist, the index finger pointing heavenward. A connection between the black, time-stained Devil's Thumb and this beautiful marble-like shaft was at once made in the minds of every one present, and the iceberg was named "The Hand of Providence."
The pack ice of one winter's growth is met and fought by the whalers on both sides of the continent, until, with the assistance of the summer sun, it is conquered, and no longer forms an obstacle to progress northward.
Hayes states that the formation of new ice in Foulk Fiord during one winter in still water was thirteen feet thick. It is highly improbable that any additions at that depth would be made during even extraordinary cold periods; it has since been surmised by experienced arctic travelers that a portion of this thickness was due to snow deposits. Ordinarily, this ice will not be found thicker than seven feet. Early in summer it breaks up and floats away in immense floes as pack ice; sometimes, through pressure, becoming hummocked or piled in thicknesses of three or four fold into the size of small bergs or crushed into fragments, until it finally melts out of sight away to the southward. This ice can be distinguished, even when hummocked, from that formed by broken-up bergs by its opaque-white color, due to the presence of innumerable air-cells, its method of formation rendering it softer and more porous than glacier ice, which is subjected to years of pressure and concentration through infiltrating streams of freezing water.
Before the immense floes are broken up, however, they are extremely dangerous in the confined Greenland waters, where they are continually subjected to terrible pressures by the winds and surface currents. The eastern whalers, through superior equipment and working in company, escape many of the disasters of the Americans in the Pacific, while their proximity to land or fast ice and numerous villages of Eskimos gives them strong hopes of rescue, even though their vessel may be lost. After arriving at their station they have little to fear but floating bergs and hummocks, their powerful steamers crushing the then rotten floe ice with ease. As the whales leave the vicinity of Pond's Inlet early in the summer, the whalers strive to get there as quickly as possible; a large reward being often given by the owners to the crew of the vessel first reaching that point. They can afford this, as her cargo may consist largely of whalebone collected by the Eskimos in the vicinity. These men are, in consequence, the best ice-navigators in the world.
Our own American whalers have no such incentive; they are no less hardy or brave than any seamen in the world. Their life is a hard one; in case of disaster there is no such way of escape as that open to the Scotchmen in the east; and yet it would be comparatively easy to establish a life-saving station on the north coast of Alaska, which would repay perhaps more than any other on our coasts. There is but one narrow passage for the Bering floes, and the ice after passing through the strait scatters and becomes easier to avoid. The pack is not confined and caused to revolve between immense icebergs or many narrow passages, as in Greenland or eastern waters, so that the recent employment of steam whalers, instead of the old-time sailing vessels, has been dictated more by a desire for increased profits than by actual necessity.
But there is another and more dangerous ice than floe ice, as it takes many years for its formation. It is met with in isolated floes, but rarely if ever in pack below Smith's Sound, and the Scotch whalers seldom encounter it. Ships have been nipped hundreds of times in floe ice and escaped, but few if any have ever freed themselves from the fierce grasp of the ancient ice of the arctic, called by Nares floe-berg or paleocrystic ice. This bears evidence of great age, the part above water being from fifteen to forty-five feet in thickness, which would make its depth from one hundred and thirty-five to four hundred and five feet; the stoutest-built ship that ever put to sea would be crushed into matchsticks by the pressure of two such floes upon her sides. This ice forms the northern limit of the cruising-grounds of the American whalers north of Alaska. Some years it moves to the southward and closes up on them; again, it recedes, disclosing more of the mystery of the farther north. Scattered here and there through it are polynias, or lakes of ice, of one year's growth, inclosed by heavy floes arched and keyed together.
Paleocrystic ice is old pack ice built up by successive deposits of snow during a long period of time, thus giving it an appearance of stratification. There is an alternation of soft white and hard blue ice, representing, respectively, compressed snow and water formed during the sunshine by thaws, and frozen at night or when cloudy. (It is a remarkable fact that snow will melt and seep through floe ice in sunlight though the thermometer may record far below the freezing-point.) Eventually, during the long summer day, the floe is left bare and dry, but soft and porous, unless so far north that the snow-storms continue all the year round. Over some strata are layers of atmospheric dust, such as Nordenskiöld found on the Greenland glaciers; also the gradual decrease of the thickness of the layers—due to pressure and increase of blue ice—because of greater infiltration, as the lower part of the berg is approached, make certain the progressive nature of the formation.
Beyond the Melville Bay pack, averaging six feet in thickness, lies the "north water" of the whalers, corresponding to the open space usually found between the paleocrystic pack and Bering Strait. This is dotted with hummocks, rubble ice, or broken-up bergs, and icebergs of enormous size, which it is easy to avoid except in the frequent fogs of the summer months. These icebergs break from the immense glaciers bounding Melville Bay and Kennedy Channel, which occasionally rise two hundred feet above the water. It is apparent that the bergs breaking off irregularly might, through a bulky form of the submerged part, attain a still greater height. Hayes mentions a berg over three hundred feet high in the "north water"; the Proteus on her last trip sighted one a hundred and fifty feet high, six miles long, and a little more than a mile wide. These immense bergs are most important agents in breaking up the ice-fields in early spring, for, being propelled by deep under-currents, their motion is often contrary to that of the floe ice moved by the wind and surface currents.
The wind also plays an important part, a southwest gale sending the packs and hummocks upon the edge of the fast or land ice, and crushing it for some distance, after which any northerly wind disengages the free ice, leaving an open space, called the inshore lead, which the earliest whalers always follow. It is, of course, dangerous, as a south wind sends the pack back, and imprisons if it does not crush them. In July the quicker way through "the middle passage" of the Melville Bay pack is used, as the ice is then comparatively harmless, although vessels are sometimes nipped and rather severely handled.
No stronger vessels than those of the Dundee whalers are built; they are from four hundred to one thousand tons displacement, have powerful, well-secured engines to resist the shock of ramming or stoppage of the propeller by ice, and are built with an eye to the easy and rapid replacement of rudder, propeller, and propeller-shaft if damaged, these parts being carried in duplicate. Above all other considerations, they possess strength for ramming as well as resistance to lateral pressure when nipped.
Another very important feature is that the bow shall have considerable inclination, which permits the vessel, when ramming very heavy ice, to lift slightly and slide on it, thus easing the shock and assisting the cutting action of the bow with the downward crushing weight of the ship. In this way it is possible for these steamers at full speed to ram ice over twenty feet thick, and receive no immediate incapacitating damage.
If the ice is not too heavy, the shear-like rise and fall of the bow is repeated several times as the vessel steams powerfully ahead until her headway is checked. The difficulty then is to extract the ship from the dock she has cut by her advance: the floes press on her sides, cakes of ice and slush fill her wake, and there is nothing but the ice-hampered propeller with which to overcome her inertia and draw back out of the nip. Frequently this is insufficient, and the ship may be crushed.
In breaking up a floe of great extent and thickness, which is rarely attempted, as the coal and labor thus expended might be saved by a movement of the ice in a few hours, two vessels work to great advantage in concert, striking alternate blows at an angle with each other, thus breaking off wedge-shaped sections, which are shoved out of the way as fast as an advance is made into the floe.
Various other methods are employed for breaking a way through the ice or relieving the pressure on the ship, but they are all insignificant compared with the mighty results of dashing and fearless ramming. Without it, in spite of the utmost exertions of officers and men, Greely would not have been rescued. The dispersive effect of explosives in water-soaked ice is small, and placing the torpedoes requires time; the ice-saw is clumsy, slow, and rapidly exhausts an already overwrought crew, while warping and towing floes are but the last safeguards from despair.
The Dundee skippers are not held to too strict account for damages that the vessels may sustain during their short but exciting cruise. Desperate risks are taken every day; the man who fears responsibility would never succeed, while another hesitating or lacking resource would quickly lose his ship. Starting from Dundee in April, they generally reach Godhavn, in latitude 69° 15' north, before June, but from that point to their destination it is a long and plucky fight with the ice. Continually following up the breaches made in the solid field by storms and tides, their only fear, though surrounded by floes capable of crushing the ships if taken unawares, is that the lead will open in some other place, leaving them inclosed by vast immovable floes until some rare northwest wind loosens the pack, or the summer's sun so weakens it that the ship is able to smash through and escape.
On the approach of a gale, when the ice may be expected to move rapidly and through its great weight and extent accumulate pressure, a fine solid floe is selected in which to form a protected dock. In it the ship is rammed as far as possible, if necessary the slip being deepened with the ice-saw; so long as the floe holds together the ship will be subjected to the pressure of only those small fragments that may be forced into the entrance to the dock.
To take advantage of every little patch of open water in breaking through the pack, a pilot is stationed aloft in the "crow's nest"; this is a large cask, with a trap-door in the bottom for entrance, secured to the mast. It is sometimes quite cozy, being fitted with a wind-screen, rest for the long glass, engine-room bell pull or indicator, helm-director, and compass. The height of the observer is about one hundred and fifteen feet, and the greatest distance at which ordinary pack ice is visible from that height is less than seven miles; it is evident, then, how much experience and judgment are necessary in directing the movements of the ship, the only indications at times being doubtful ice-blinks and undecided water-skies.
The ice-blink is frequently a very weak indication in summer, appearing as a narrow belt of a little lighter and yellowish sky just above the horizon. So faint is its appearance at times that it would not be recognized except by comparison with known water sky. The latter is dark and gloomy, much resembling that preceding a thunder-storm.
In the pack itself it is generally calm, a slight breeze being almost certain evidence of the close proximity of considerable open water.
The sealers of Dundee and St. John, Newfoundland, rendezvous at the latter port and start almost in the same half-hour about midnight of some day in March. The date is fixed by law, in order to protect the seals during their bearing' period. They have a less venturesome voyage than the whalers, though starting earlier, their hope being to meet the first great ice-floes in the open sea where they are subjected to very little pressure, though the fogs and dark nights make it difficult to avoid collision with one of the numerous icebergs.
The sealers depend in a great measure on luck to strike the floes on which the hair-seal is found in great numbers; a few of the oldest captains are supposed to possess a prescience or peculiar judgment, though it is by no means certain that the seals will be met with in the same part of the open sea in two consecutive seasons. In fact, out of ten or twelve sealers leaving in the same hour every year, it frequently happens that one or two of the luckiest have made two successful trips with full cargoes before some of the others have reported more or less bad luck from their first; the Proteus once brought in one hundred thousand skins from her first trip of the season alone.
On sighting the ice the steamers run along the great floes and through the leads until they find a floe on which a colony of seals have congregated; a dock is rammed into the ice at once; ice anchors are laid out ahead; the very large crew carried is landed by the Jacob's ladders dangling from the head-booms. Sometimes the crew is split up into several parties to work on different floes; in all cases the seals are surrounded as rapidly as possible and driven toward a common center. Here they crawl up on each other, barking and moaning, until they form a great heap ten feet or more in height, writhing and fighting, while the ice in every direction is dotted with the white puppy-seals so young as to be unable to move. The men at work on the ice esteem very highly the frozen hearts of these young seals, claiming that they are not only palatable, but enable them to better stand cold and fatigue. The seals having been concentrated, the work of slaughter commences: each man is armed with a pole having a hook attached to one end, with which the seals are one by one drawn from the pile and killed by a single blow on the head. The skin is then quickly removed with the fat blubber, which is wrapped up in it; it is valueless as fur, and eventually tanned, split, and made up as imitation kid into gloves, linings of porte-monnaies, valises, shoes, etc.
In less than two months after the sealers first start out, the seals have completely disappeared; where they go is a mystery. In the fall they reappear in small groups making their way north again.
The whaling season then follows immediately after the sealing, the same steamers sometimes being employed.
Early in September, whether the season has been successful or not, the Dundee whalers start on their return voyage, following the east coast of British America and Labrador until they lose the benefit of the polar current near Newfoundland.
It is a rough trip; gales and tremendous seas are peculiar to both time of year and locality, yet it may be considered almost uneventful to the crews of those racked and bruised vessels which will require the whole winter to refit for next season's work.