Part 2 — ICEBERGS.

BY J. V. HAY.

It may sound strangely to the average reader to say that icebergs are more numerous in warm weather, but such is the fact. Of course they are formed in winter, but it takes the summer sun to set them adrift and send them floating on the ocean, a grand sight to look at but a fearful menace to vessels.

Icebergs are born every day in every month, but most of them remain in or near their native waters for a long time before they escape and wander to the great lanes of travel between here and Europe.

The bergs seen last summer are from two to ten years old—that is, they have had an existence individually for years, though the ice from which they are formed is much older, some of it possibly having been frozen first a thousand years ago.

Icebergs are born of glaciers, and four out of five of the floating bergs on the Atlantic come from Greenland. A glacier is a river of solid water confined in the depressions running down the mountain sides.

Soft and powdery snow falls upon the summits, and though some is evaporated, the yearly fall is greater than the yearly loss, and so the excess is pushed down the slope into the valleys which possibly at the time are covered with green and have afforded pasture lands for cattle.

The snow gathers in the high valleys and every day undergoes some degree of the change which finally transforms it into ice. Slowly, very slowly, in some cases only a foot every year, this frozen river flows downward. Nothing can stop it, nothing can even check it.

The process is the same in Switzerland and Greenland, only in Switzerland the glacier melts when it reaches the lower valley and feeds rivers; in Greenland the glacier slides into the ocean, breaks off and becomes an iceberg and floats away.

One of the incidents of an ordinary Alaskan cruise along the coast is to see the glaciers break off and fall into the water. They are far more beautiful than the finest of the glaciers of Switzerland, and in size they are so great that the largest Alpine glacier would make only a fair-sized nose, if it could be taken bodily and placed upon the face of one of the Alaskan giants.

At Glacier Bay icebergs are being born all the while. Muir Glacier, the largest that dips into the bay, presents a front of 5000 feet. It is 700 feet thick, five-sevenths of it being under water. It extends back for miles and miles.

Each day the central part moves 70 feet into the sea, the discharge every twenty-four hours being 140,000,000 cubic feet of clear ice. As this great quantity cracks into pieces from the glacier, the bergs of the North Pacific begin their life. The separation from the larger mass and the plunge into the sea cause terrific noises.

The interior of Greenland is a solid mass of ice. In fact, some people think that at about the central part of Greenland there is a high mountain, around whose sides there has grown through the centuries an enormous glacier, sending down in every direction branch glaciers that extend to the coast. It is known that the only part of the land which is not covered completely by ice is a narrow belt around the shore.

Crossing this belt at hundreds of places are the glaciers. Some are only a few hundred feet wide and 50 feet thick, while others are several miles wide and measure 1500 feet from surface to bottom.

All of these ice streams are making their way to the sea, and as their ends are forced out into the water by the pressure behind, they are broken off and set adrift as bergs.

Ensign Hugh Rodman, of the United States navy, in his report on the "ice and ice movements in the North Atlantic Ocean," explains many interesting things about ice and bergs.

Once the glacier extends into deep water, pieces are broken off by their buoyancy, aided possibly by the currents and the brittleness of the ice.

The size of the pieces set adrift varies greatly, but a berg from 60 to 100 feet to the top of its walls, whose spires or pinnacles may reach from 200 to 250 feet in height and from 300 to 500 yards in length, is considered an average size berg in the Arctic. These measurements apply to the part above the water, which is about one-eighth or one-ninth of the whole mass.

Many authors give the depth under water as being from eight to nine times the height above. This is incorrect, and measurements above and below water should be referred to mass and not to height.

It is even possible to have a berg as high out of water as it is deep below the surface, for if we imagine a large, solid lump, of any regular shape, which has a very small, sharp, high pinnacle in the centre, the height above water can easily be equal to the depth below. An authentic case on record is that of a berg grounded in the Strait of Belle Isle, in sixteen fathoms of water, that had a thin spire about one hundred feet in height.

Each glacier in Greenland, so far as any estimate has been made, is the parent each year of from ten to one hundred icebergs. When these bergs have plunged into the Arctic Sea, they are picked up by the Arctic current and begin their journey to the North Atlantic. But there are thousands of them afloat; they crowd and rub against each other and frequently they break into smaller masses.

Many go aground in the Arctic basin; others get to the shores of Labrador, where from one end to the other they continually ground and float. Some disappear there, while others get safely past and reach the Grand Banks.

According to Ensign Rodman, the ice of bergs, although very hard, is at the same time extremely brittle. A blow of an axe will at times split them, and the report of a gun, by concussion, will accomplish the same end.

They are more apt to break up in warm weather than in cold, and whalers and sealers note this before landing on them when an anchor is to be planted or fresh water to be obtained.

On the coast of Labrador, in July and August, when it is packed with bergs, the noise of rupture is often deafening, and those experienced in ice give them a wide berth.

When they are frozen the temperature is very low, so that when their surface is exposed to a thawing temperature the tension of the exterior and interior is very different, making them not unlike a Prince Rupert's drop.

Then, too, during the day, the water made by melting finds its way into the crevices, freezes, and hence expands, and, acting like a wedge, forces the berg into fragments.

Much of the ice encountered at sea is discolored, and often full of dirt and gravel, while not infrequently stones are found imbedded in it.

Along the shores of Labrador, where there is a large rise and fall in the tide, ice is brought into contact with the bottom, and mud and sea-weed are frozen in with it, while at times landslides precipitate large quantities of dirt and stones on its surface.

As the ice leaves the coast and comes to the southward, it brings these burdens with it, which are deposited on the ocean bottom when the ice melts. As this melting occurs to a great extent over the Grand Banks, it would seem that the deposit from the field ice would be greater than that from bergs.

It is hard to understand why bergs should have foreign substances frozen into them, as they are formed from snow deposited on the frozen surfaces in the interior of Greenland, and hence their thickness is added to from their upper surface.

It is possible that in their journey south in the Arctic current they accumulate more or less foreign matter by having it ground into their bottoms; but this does not seem probable, as it is hard to force gravel into ice and give it a permanent hold, while mud accumulated in this way would soon be washed out.

Then, too, the largest bergs find their way around the edges of the Banks, and do not cross, on account of their draught, for only an average-size berg crosses the Banks.