THE NEW CONTINENT.

New Zealand Tablet, Volume IV, Issue 174, 28 July 1876, Page 12

THE NEW CONTINENT.

In the ' Popular Science Monthly ' for April is an article by Prof. C. C. Merriman, entitled, " The Polar Glaciers," which narrates some facts but recently discovered, and records some remarkable conclusions. A condensed summary of these facts and conclusions will prove of interest to all. The centre of gravity of th« earth is the centre of the sphere formed by the surface of the oceans — making slight allowances for polar flattening, it is a point equally distant from the level of the sea on all sides. In each hemisphere the sea level in the samelatitude would be at the same distance from the centre, and whatever excess of visible land there is in one-half must be balanced by some corresponding weight in the other half. And it is evident that this counterpoising weight must, in fact, be land, supposing, as is almost certainly the case, that the hemispheres are equally heavy according to bulk. It therefore follows to a mathematical demonstration that there is exactly the same weight of land projected above the water in both hemispheres. But the map of the world, as geographers have outlined it,, shows that there is apparently a vast preponderance of land north of the equator. Humboldt estimated that Asia stands at the average height of 1,150 feet above the sea ; South America, 1,130 y. North America, 750; Europe, 670. The average height of the whole — omitting Africa and Australia, which are about as much south as north of the equator — is 920 feet. There are in the northern hemisphere 44,000,000 square miles known to geographers; in the southern, about 16,000,000 — little more than a third as much — leaving a difference of 28,00,000 square miles averaging 920 feet high. k. But as there is the same visible excess of water on the soutpgrn side that there is of land on the northern, and as the depth of the sea is about the same, it follows that the weight of the excess of submerged land in the northern hemisphere must be added to the 28,000,000 square miles, doubling the height of it, and making it at least 1,840 feet above the average level of the southern continents and oceans' depths. What is there south of the equator to balance this ? We must have something, or the earth would not maintain its poise. There must be something on the southern side to balance the orb and make the water level possible. This balancing weight is estimated by Professor Merriman tolie (on that vast unexplored and inaccessible region, as large as North America, that caps and surrounds the southern pole. But supposing this 8,000,000 miles within the antartic circle to be land, it would still require over it all an average thickness of two and a half miles of solid ice to n ake the southern hemisphere equal the northern in weight. This vast iceberg Professor Merriman believes to exist. The voyages of explorers thereaway seem to confirm this hypothesis. They have not been able to penetrate the high and formidable ice barrier which masks this desolate region. No sign of animal life or vegetation is there, while within the arctic circle at the north there are numerous settlements and whole races of men. In the north sledges have penetrated within 600 mile* of the pole ; in the

south no man ever ventured within 1,500 miles. What causes this great difference ? The explanation is plain. Owing to its eccentric movement around* the'sun our northern summer is some eight days longer than our winter, while in the couth the winter is eight days longer than the summer. This sixteen days makes such difference, which is emphasized hy the additional fact that during the long southern winter the earth is farthest from the sun. Thus year after year, for a long period, there has teen a steady accumulation of ice material about the south pole, adding weight to that hemisphere. Then as this weight of ice increased the earth's centre of gravity Jhas'gradually moved to the south, and the waters fluent and obedient to gravitation have slowly gathered into southern seas, covering the lowlands of the south. At the same time this transfer of weight from the north has drawn the waters a'tfay from the Arctic regions and left the scabars and shoals to project and become habitable. But this state of things is not always to go on. The north is not always to bask in the longest summer. The earth, in addition to its diurnal and annual revolutions, has a slow wabbling of its axes in the heavens. It is precisely as when one touches the rim of a "top in rapid motion, the upper end of the stem describes a small circle. So the mighty sun lays hold of the protuberant rim of the great terrestial top, and it begins to oscillate in the long period of 21,000 years. That is to say, on December 21, 1248, the earth made its nearest approach to the sun ; and it will approach equally near in 10,500 years from that time, or in the year 11,748, on the 21st"of July. In the period, comprising the first case our northern winters are short and mild and our summers long and sunny. During the period of which the year 11,748 will be the middle, our winters will be severe and our summers short. The northern hemisphere is now losing its great summer. In about 10,000 years it will be in the midst of its great and terrible winter. (Then the southern hemisphere will be full of sunlight and prolonged warmth. Now let us see what would result from this. The melting of a mile in thickness of the ice-cupola of the south pole would raise the sea-level at the north pole 300 feet, at London 200 feet, and at New York 200 feet. If the whole ice-cupola were removed and an equal quantity deposited at the north pole, there would be a deepening of the sea at the arctic circle of 1,500 feet; at New York of considerably more than 10,000 feet. Thus it is seen that, as certainly as terrestrial revolutions continue, in the course of 10,000 years there must come an entire reversal of polar conditions. The southern waters must be drained off to make th<» oceans of an opposite hemisphere. New lands, enriched with the sediment of a hundred centuries, will rise up to extend the borders of the old south continents, and islands joining together will expand |into mainlands. At the same time the northern continents must be in a great part submerged and their summits and ranges become the bleak islands and the bold headlands of a tempestuous ocean. Central Asia, with its broad table lands, may still retain the name of a continent; but beyond a few out-lying islands there will be no Europe and but little of North America left. The Atlantic waters will stand 500 feet over Lake Superior, and will wash the base of the Rocky Mountains in all their length. A new Gulf stream may again, as it must often have done before, flow up the Valley of .the Mississippi; returning the deltas to the prairies and remaking the beds of the garden of the world. These are no idle or impossible fancies. Not only are they results of rigorous calculation, but ;they accord perfectly with the unmistakable evidences which the ocean has left on all our land of its recent work and presence.