ATLANTIC ICE.

Star (Christchurch), Issue 10440, 20 April 1912, Page 6

ATLANTIC ICE.

THE DANGER TO NAVIGATION. A PROBLEM OF GRAVE IMPORTANCE. . The wreck of the Titanic has directed anxious attention to tho old problem of tho vagaries of the ice-drift in the North Atlantic Ocean. The question was dealt with interestingly a few years ago by a writer in "Chambers's Journal."

Of all the incidental difficulties and dangers, ho wrote, that beset the navigation of the North Atlantio, there is none that causes so much anxiety to the mariner as detached ice, whether existent in the form of floes or bergs. The season of 1890 will long be remembered in the nautical and scientific world as being quite phenomenal in regard to tho quantity of ic© reported, and the geographical limits within which it has been encountered. But it is by no means easy to obtain definite information on the subject. It is true that the regular Atlantic liners carefully note and report the position of the ico encountered by them; yet, until the laws that govern the magnitude and the range of the Atlantic drift-ice are more accurately known, such reports do little else than sound a note of alarm to tho navigator, apprising him of the existence of a danger, but leaving him quite •in ignorance as to the locality where it may next be encountered. In ordinary seasons, it is assumed that the detachment of the bergs from the parent glaciers in Greenland does not take place until May is well advanced; that when free from the ice that has covered laud and sea alike during the Polar winter, they set out on a southerly journey into the wanner waters of tho Atlantic, slowly urgod on their voyage by the chill waters of a ! cold drift-current that ever flows through the depths of the Atlantic from Pole to equator. It is strange that the language of agriculture should be requisitioned to describe phenomena so distinctly antagonistic as that presented by Arctic ice. An expanse of ice resting upon and covering the sea with a coating of uniform thickness is spoken of as an ice-field; while the process of severance whereby a berg is detached from the glacier is alluded to as calving. The calving process, however, would seem to have occurred at a much earlier date in 1890 than in previous seasons, for as early as April 22 the steamer La Gascogne, while on a voyage from New York to Havre, reported passing three icebergs, all of great size, in latitude 42deg Simla north. For icebergs to have reached so far south at such a date is most' remarkable,- and as far as our present knowledge of the climatic conditions of the Arctic ice regions is concerned, quite unexplainable. During the months of May and June hardly a voyage was made across the North Atlantic without ice being reported, many steamers having to make most lengthy detours to avoid it; and several firms, with a praiseworthy prudence, mapped out a much more southerly course for the vessels of their fleets, wisely choosing a longer passage, than run tho risks of collision with field or berg- ice. The progress of a berg from its home in a Greenland fiord, down through Davis Strait and along the desolate shores of Labrador, is necessarily a very tardy one. Passing Labrador, they glide slowly over the Banks, losing no inconsiderable portion of their, bulk whenever they strand in the shallows of that region. Even when an iceberg has its base deeply embedded in the seabed, tho check to its voyage is often but of short duration. The restlessness of the sea, the influence of the tides, and.' tho over-constant propelling influence of the Labrador, current, soon effect its release, and onward it glides in ghostly majesty, its base hidden in the depths of the ocean, and its pinnacled summit shrouded in an impenetrable mist. The detaohed fragments, the broken snouts of the berg, severed by friction with tho ocean floor, freeze again to the sides of the berg as it pursues its southerly course, like a monster ship of ice surrounded by a flotilla of attendant shore-boats. From Newfoundland the moving ice follows the trend of the North American shore, gradually decreasing in mass, until, reduced to a liquid, it is lost in the waters of the surrounding ocean. The dissolution, however, takes a considerable time to accomplish. The two melting forces, the warm air and warm water, into whose influence the berg advances, receive a very material check by reason of the air and water which are in immediate contact with the berg. As the ice slowly melts, fresh water will result, and this, by virtue of its lesser specifio gravity, floats upon the surface of the ocean. The temperature of this surrounding area of fresh water will bo very little, if anything, above the freezing-point." The air above this zone of fresh water will naturally take the same temperature, while that contiguous to tho berg itself takes the temperature of the berg; so that the iceberg is surrounded with an aerial and water blanket many degrees below the normal temperature of tho region through which the berg passes. Aided by these hindrances to a speedy dissolution, icebergs have been known to float as far south as tho latitude of Gibraltar before they have wasted away. The envelope of fog that surrounds that part of the iceberg above sea-level, .ohilling as is its effect upon the ocean voyager, is not an unmixed evil, for its presence often servos to notify the proximity of ice. The season of 1889 was one of comparative immunity from Atlantio icedangers. Why the succeeding year should he so prolific of both berg and field ice is as-yet unexplainable. It is suggested, however, "that the prevalenco of severe northerly gales during tho whole of December and part of January, 1889-90, contributed not' a little to set the ice free in larger quantities and at an earlier date than usual. Another peculiarity of the 1890 season is the remarkable fart that the ice has penetrated farther eastwards than it has been known to do before. The master of the sealing vessel Terra Nova, while on a voyage from Newfoundland to Dundee, encountered many large bergs, one of the largest being found in 50deg north and 41deg west. Subsequent reports show that both field and berg ice have been met with even two degrees farther eastwards than the position cited above. This eastward extension of the ice during 1890 may have been caused by some abnormal influence of the Labrador current, or by the supposition that bergs may have entered upon, tho drift of the Gulf Stream before they had been melted, and were in consequence slowly carried to tho northward and eastward. Tho locality in which tii3 ice has been thickest is that where tho Labrador current impingea upon tho waters of the Gulf Stream. Here both currents become considerably enfeebled, and tho tergs accumulate in consequence. In spite of such an abundance of ice, maritime disasters therefrom have been iruvt rare. No higher tribute can be paid to the prudence and skill of North Atlantic navigators than to btate that no serious calamity by ice collision has occurred, and except in one or two instances, the regularity and punctuality of Atlantic voyages have not been interfered with. Perhaps the nearest approach to a disastrous collision with a berg was that experienced by tho Normanma. Between latitudes -Ifrdeg 29min and 45deg 20min north, and longitudes 42deg 2inin and -ISdoy; west, no fewer than twenty-fivo icebergs were descried, and with one of these the ship collided. Fortunately, the damage was trivial, and all above* tho water-line. It was during a. dense fog that tho iceberg wus •widfinlj sighted, and, bofyro tho r«-

versal of the engines had timo to take tho way off the ship, she struck it broadsido on. Tho passengers scarcely felt tho shock, for the vessel immediately glanced off tho berg into clear water. A littlo less vigilance and a little less promptness on the part of the captain and crew of tho Normannia, and she had no doubt gone to swell the ranks of the missing. A similar accident, the disastrous consequences of which were averted in a similar manner, befell the Thingvalla. In the case of the Beacon-Light, nn Atlantic liner provided with a pewerfnl searchlight, the collision ivas of a somewhat more serious nature. Her log reports: "During' a heavy fog at midnight an immense iceberg was discovered towering above the ship not seven ty-fivo feet away. Orders were given to alter the helm and reverse the engines, but not altogether in timo to clear tho berg, which was struck by the starboard bow of the steamer. A largo quantity of ico was dislodged, and tho ship was considerably damaged, but brought safely into port." Collision with the berg is not the only danger to be feared from a too close propinquity with an iceberg. Exposure to an atmosphero many degrees warmer than itself causes the ico to assume a spongy • character, highly favourable to tho severance of fragments of all sizes upon the least disturbing influence being brought to bear upon it. Tho vibration of the air caused by the sounding of a steamer's whistle has been known, in the case of "porous ice,".to detach large masses from tho berg;, while a gun fired in the neighbourhood of a similar berg produced atmospheric concussion sufficient to bring down enough ice to destroy any vessel upon which it fell. It must bo borne in mind, however, that the severance above alluded to was only effected, with bergs the ice of which was " spongy and rotten." Below tho water-line the changes in the ice-mass are much to be feared by a vessel that happens to bo near when they occur. The detachment of huge blocks often shifts the position of a berg's centre of gravity, with tha result that tho iceberg immediately capsizes, crushing everything in its immediate neighbourhood. As far back as 1875, the adoption of steam lanes a considerable distance to tho southward of the usual course of Atlantic liners was advocated; and it is satisfactory to observe that common prudence impels mariners to cross the 60th meridian during the months of March, April, May and June at a point much farther to the (south thnn their point of intersection during the other months of tho year. Many firms, however, do not rely too much upon the discretion of their commanders, but carefully procuring all the available information relative to tho quantity and drift of the '•», they map out a course for them accordingly.

The pilot chart iasued in June by the United States Hydrograpbical Departs ment indicated that the prudent course for vessels proceeding eastwardly was to crass longitude 47 degrees at latitude 40 degrees north. The westerly course is to cross the same longitude at latitude 39 degrees. Tho adoption of such precautionary measures has no doubt done much to minimise the risks of ocean voyaging during the ice-sea-son; but the question naturally arises, cannot anything be devised which shall givo the mariner sufficient warnir.r of tho proximity of iceP Up to tho present, nothing of a reliable nature has yet been invented. The most powerful electric searchlights were inefficient in the case of the Beacon-Light to reveal danger until it was but some 75ft away. It has been suggested, however, that by means of a thermopile and a galvanometer, and an ordinary mercurial thermometer for recording the temperature of the surrounding atmosphere, a very effective ice-indicator can be made. A movable contactbreaker should be fitted to the galvanometer, and this should be' set at a point considerably below the temperature recorded by the thermometer. When the mercury in the thermometer falls to the point at which the movable con-tact-breaker of the galvanometer Is placed, the thermopile by means of an electrio alarm-boll notifies this fact, and this sudden fall in the temperatore suggests that the fog-bank concoals an iceborg. In the case of a sudden fall in tho'temperature, the warning of the thermopile would prove invaluable; but it is by no means satisfactorily established that the_ envelope of cold air surrounding on iceberg is separated from the normal air of the region outside the area of the here's influence by so definite a lino of demarcation as a sudden diminution of temperature of ten degrees. It is more probable that the transition from the normal temperature- to the cold air in juxtaposition to the herg < i« an extremely gradual one; and in that ca.«o ordinary observation would prove almost an efficacious as the somewhat elaborate plan alluded to above. Such dangers as field and berg ice entail upon tho navigator can hardly have failed to call into existence a host of suggestions as to the best way of removing them. That which baa occurred to many is that a vessel of war should be employed to patrol the Atlantic and destroy by firing upon or other means any berg it may encounter. The idea of enlisting the forces of war to facilitate the commerce of the nation is not without its attractiveness. Unfortunately, however, such a scheme meets with no favour from practical men. It must not be forgotten that the specific gravity of ice as compared with water is as .9 to 1, bo that something like nine-tenths of the mass of tho berg is below the sea-level. The destruction of the pinnacled summits of the berg would simply mean the reduction of tho berg to a more compact form, and the consequent lessening of the visible area of the iceberg. An iceberg with a summit rising some ninety or a hundred feet above the sea is undoubtedly a great danger to safe navigation; but except when ebscured by fog, it is a danger that reveals itself for a considerable distance. A mass of ice, however, over which the sea washes, or which is elevated above the waves but to the height of ten or fifteen i'eot, is a danger much more to be feared. The difficulty is clearly one in which prevention is tho best cure. A fleet of ocean patrols could easily detormine the quantity of ice, and the rate of its drift, that was likely to intersect the trado routes across the North Atlantic. Such knowledge rapidly and widely disseminated by means of despatchboats and tho electrio telegr.tijfi would do much to reduco ice dangers to a minimum. There is ono other phase of Atlantio ice-phenomena that stands in need of elucidation. It has been proved beyond doubt" that of the bergs carried southwards by tho Labrador current, some find their way back to what has aptlv been termed the " Palreocrystio Sea." The direction that such bergs take, and the course they must drift to avoid the continuance of tho southerly direction that must sooner or later result in tho liquefaction of the largest bergs, are at present shrouded in mystery. It is matter for discussion whether the sur-fnce-drift of the Gulf Stream is sufficient to deflect a berg to tho northward and eastward. The solving of these problems is calculated to benefit in the* hijrheot degree possible the North Atlantic trad", for it w a phase of marine exploration that will go far to develop the truth of the aphorism. "The. but join the nations they divide," find so knit closer together the great T'higlish-sppnkinK peoples separated by tho waters of the Atlantic Ocean.