The "Fram" observations showed that while the ordinary diurnal range of temperature prevailed for the months when the sun was above the horizon during some part of the day, there was also a diurnal range in the winter months when the sun did not appear, the minimum then occurring about 2 p.m. and the maximum about 1 a.m., the "day" being colder than the "night." Except in July and August the temperature was always found to be lower with the weaker winds and higher with the stronger winds irrespective of direction. Extraordinarily rapid variations of temperature have been observed in the winter months, on one occasion in February 1896 (north of 84° N.) the thermometer rising within 24 hours from -45-4° to 22.3° F., a rise of 67.7°.

Cloud and Precipitation.-The amount of cloud in the far north is greater in the daytime than at night, the summer months being cloudy, the winter very clear, and the amount is greater with the stronger winds and less with the weaker winds. Precipitation is most frequent in the summer months, the "Fram" results showing an average of 20 days per month from May to September; while from October to April the average was only 11 days per month. Rain was only observed in the months from May to September; but snow occurs in every month and is most frequent in May and June, least frequent in November and December, which are the months of minimum precipitation. It has never been possible to make satisfactory measurements of the amount of precipitation in the Arctic regions on account of the drifting of snow with high wind. Fogs occur most frequently in July and August (20 or 16 days per month); they are practically unknown between November and April.

Pressure. The "Fram" observations enabled Professor Mohn to revise and extend the isobaric maps of Dr Buchan, the correctness of which was strikingly confirmed. The Atlantic and Pacific low pressure areas are found at all seasons on the margin of the Arctic area, the position shifting a little in longitude from month to month. The two low pressures are separated in the winter months by a ridge of high pressure (exceeding 30.00 in.) stretching from the Canadian to the Siberian side between the North Pole and Bering Strait; this ridge has been termed by Professor Supan "the Arctic wind divide." In April the high pressure over Asia gives way and an intense low pressure area takes its place during the summer, uniting in August with the less intense low-pressure area which develops later over Canada, and reducing the Arctic high pressure area to an irregular belt extending from North Greenland to Franz Josef Land on the Atlantic side of the Pole. The general pressure over the polar area is much higher in winter than in summer and the gradients are steeper also in the cold weather, giving rise to stronger winds. The isobaric conditions indicate light variable winds in summer along the route of the " Fram " from the New Siberia Islands to the north of Spitsbergen, and in winter south-easterly or easterly winds of greater force; this is in accord with the observations made during the drift. Professor Mohn believes that the maximum pressure at the North Pole takes place in April, when it is about 30.08 in.; and the minimum pressure from June to September, when it is about 29.88 in., the annual range of monthly mean pressure being thus only 0.20 in., so that the Pole may be said to be in a region of permanently high atmospheric pressure. Cyclonic depressions crossed the region of the "Fram's" track with considerable frequency, 73 being experienced in the three years, the frequency being greatest in winter but the wind velocity in cyclones greatest in summer; the most common direction of movement was from west to east. The average velocity of the cyclonic winds encountered by the "" Fram was only about 29 m. per hour, the highest 40 m. per hour, the portion of the Arctic Sea she crossed being much less stormy than the coasts of the Arctic lands, where winds have been recorded of far greater severity, e.g. 45 m. per hour in Spitsbergen in 1882, 55 m. per hour in Teplitz Bay, Franz Josef Land, in 1900, 62 m. per hour on the Siberian coast in the "Vega" in 1879, and as much as 90 m. per hour at Karmakul

interior of the polar area is a fair weather zone as compared with its margins, where the contrast of the seasons is more marked.

Flora.-The land flora of the Arctic regions, although necessarily confined to the lower levels which are free from snow for some time every year, and greatly reduced in luxuriance and number of species as compared with the flora of the temperate zone, is still in its own way both rich and varied, and it extends to the most northerly land known. In some of the fjords of western Greenland and also of Ellesmere Land almost on the 8oth parallel the prevailing colour of the landscape in summer is due to vegetation and not to rock. The plants which occur on the margin of the Arctic Sea and in the polar islands represent the hardier species of the North European, Asiatic and American flora, the total number of species amounting to probably about a thousand phanerogams and a still larger number of cryptogams. The habit of all is lowly, but some grasses grow to a height of 1 ft. 6 in., and the mosses, of which the Eskimo make their lamp-wicks, frequently form cushions more than a foot in depth. Trees are absent north of 73° N., which is the extreme point reached in Siberia, or they are dwarfed to the height of shrubs as in southern Greenland, or farther north to that of the prevailing herbage. The flowers of many Arctic species of phanerogams have an intensely brilliant colour. The plains and lower slopes of the plateaux of Ellesmere Land and Heiberg Land and the plain of Peary Land north of Greenland are sufficiently clothed with vegetation to support large numbers of rodents and ruminants, the plants occurring not as occasional curiosities, but as the normal summer covering of the ground, playing their full part in the economy of nature. The cold of winter is not sufficient to put a stop to plant life even at the pole of cold in northern Siberia; and there is no reason to doubt that if there were islands close to the North Pole they would bear vegetation.

Fauna.-Animal life is comparatively abundant in the waters of the Arctic Sea, though the whalebone whale, Balaena mystecetis, has become almost extinct by reason of the energy with which its pursuit has been carried on. The white whale and narwhal still abound in the open waters as far north as ships can go. The walrus and several species of seal prey on the marine life, and the polar bear, the king of Arctic beasts, probably roams the whole surface of the frozen sea in pursuit of seals and the larger fish. The other Arctic carnivora include the Arctic fox and wolf, the latter attacking all the land mammalia except the polar bear and old musk-oxen. The wild reindeer is still found in all the circum-polar lands except Franz Josef Land; but its range does not extend so far to the north as that of the typical ruminant of the polar lands, the musk-ox (Ovibos moschatus), which now abounds only in Peary Land, north Greenland and in the American Arctic Archipelago, though it was formerly circum-polar in its distribution. The Arctic hare is almost equally characteristic and more abundant, and the lemming probably more common still. The ermine and other valuable fur-bearing animals also occur. The animals are either permanently white like the polar bear, or change their coats with the season, being brown in summer and white in winter like the hares and lemmings. The birds of the Arctic regions are all migrants, retreating southward in winter but nesting in incredible numbers on the Arctic coast-lands, and in summer probably finding their way as individuals to every part. They are mainly sea-birds, though the snow bunting, the Arctic owl and other land birds are amongst the summer visitors. It must be remembered that the elevated plateaux of the interior of Greenland and of many of the large islands are totally devoid of life of every kind on account of their unchanging covering of snow and the intensely rigorous climate due to their great altitude.

Arctic People. The conditions of life in the continental parts of the Arctic regions are extremely severe as regards temperature in the winter, but it has been found possible for civilized people to live permanently both in the extreme north of North

America and in the north of Siberia. In the north of Norway | where the winter is mild on account of the warm south-westerly winds from the open Atlantic, organized communities dweil within the Arctic Circle in free communication with the south by telegraph, telephone, steamer, and in some cases by rail also, all the year round. The climate on the coast of Norway is scarcely less favourable in the north than in the south except for the absence of light in winter when the sun never rises, and the absence of darkness in summer when the sun never sets. If there were natural products of sufficient value permanent settlements might arise in any part of the Arctic regions where there is land free from snow in summer; but as a rule Arctic land is poor in mineral wealth and the pursuit of whales and seals requires only a summer visit. The original people of the farthest north of Europe are now represented by the Lapps, who lead a migratory life, depending mainly on fishing and on their herds of reindeer. Farther east their place is taken by the Samoyedes who live along the coast of the Kara Sea and the Yalmal Peninsula; they have also a small settlement in Novaya | Zemlya. The Samoyedes, like the Lapps, live on the produce of the sea in summer and on their herds of reindeer, moving | rapidly ever the frozen country in winter by means of reindeer and dog sledges. Spitsbergen and Franz Josef Land appear never to have had native inhabitants. Along the coast of Siberia there is no continuous population, except in the land of the Chukchis in the extreme east between the Kolyma river and Bering Strait; but small settlements of many tribes of pagan hyperboreans occur here and there. North American Indian tribes wander far to the north of the Arctic Circle in Canada and Alaska, keeping their hereditary enemies the Eskimo to the coast and islands. The Eskimo of the American coast are intermingling not only with the American whalers but also with the Polynesians who come north as part of the crew of the whalers, and the pure race is tending to disappear. The traces of Eskimo encampments in the Polar archipelago, where no Eskimo now live, may mark a former wider range of hunting grounds, or a greater extension of the population. The Greenland Eskimo are the most typical and the best known of their race. A few hundred live on the east coast, where they were formerly much more numerous. The greater part of the west coast Eskimo are now civilized members of the Danish colonies, and it is stated that whereas in 1855 only about 30% of the population were half-breeds, the blending of the Eskimo and Europeans is now so complete that no full-blooded Eskimo remain in Danish Greenland. The tribe of Eskimo living to the north of Melville Bay, the glaciers of which separate them from the people of Danish Greenland, was first described by Sir John Ross, who called them Arctic Highlanders. They have been fully studied by Commander Peary, who succeeded in utilizing them in his great series of journeys, and to their aid he attributes the success of his method of Arctic travelling.

The Arctic Sea.

According to its geographical position, the Arctic Sea might be described as the sea situated north of the Arctic Circle; but according to its natural configuration, it is better defined as the gulf-like northern termination of the long and relatively narrow Atlantic arm of the ocean which extends north between Europe on one side and America on the other. By this situation as the northern end of a long arm of the ocean its physical conditions are to a very great extent determined. This Arctic gulf is bounded by the northern coasts of Europe, Siberia, North America, the American Arctic archipelago, Greenland and Iceland. Its entrance is the opening between Europe and Labrador divided by Iceland, Greenland and the American Arctic islands; and its natural southern boundary would be the submarine ridge extending from Scotland and the Shetland Islands through the Faeroe Islands and Iceland to Greenland, and continuing on the other side of Greenland across Davis Strait to Baffin Land. This ridge separates the depression of the Arctic Sea, filled with cold water at the bottom, from the deep depression of the North Atlantic. The Arctic Sea communicates

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with the Pacific Ocean through Bering Strait, which is, however, only 49 m. broad and 27 fathoms deep. The area of the Arctic Sea may be estimated to be about 3,600,000 sq. m., of which nearly two-thirds (or 2,300,000 sq. m.) is continuously covered by floating ice.

The Arctic Sea may be divided into the following parts: (1) The North Polar Basin (including the Siberian Sea), bounded by the northern coasts of Siberia (from Bering Strait to the western Taimyr Peninsula), Franz Josef Land, Spitsbergen, Greenland, Grinnell Land, Axel Heiberg Land, Ringnes Land, the Parry Islands and Alaska; (2) the Kara Sea, between Novaya Zemlya and the Siberian coast, south of a line from the north point of the former to Lonely Island (Ensomheden) and Nordenskiöld Island; (3) the Barents and Murman Sea, bounded by Novaya Zemlya, Franz Josef Land, Spitsbergen, Bear Island and the northern coasts of Norway and Russia; (4) the Norwegian Sea, between Norway, Spitsbergen, Jan Mayen, Iceland and the Faeroes; (5) the Greenland Sea, between Spitsbergen, Jan Mayen, Iceland and Greenland; (6) Baffin Bay and Davis Strait, between Greenland, Ellesmere Land, North Devon and Baffin Land.

Depths. The Arctic Sea forms an extended depression separating the two largest. continental masses of the world the European-Asiatic (Eurasia) and America. Along its centre this depression is deep, but around its whole margin, on both sides, it is unusually shallow-a shallow submarine plateau or drowned plain extending northward from both continents, forming the largest known continental shelf. North of Europe this shelf may be considered as reaching Spitsbergen and Franz Josef Land, extending over more than 10 degrees of latitude, although there is a somewhat deeper depression in between. North of Spitsbergen it reaches beyond 81° N., and north of Franz Josef Land probably somewhat north of 82° N. North of Siberia the shelf is 350 m. broad, or more, with depths of 50 to 80 fathoms, or less. In longitude 135° E. it reaches nearly 79° N., where the bottom suddenly sinks to form a deep sea with depths of 2000 fathoms or more. Farther east it probably has a similar northward extension. North of America and Greenland the shelf extends to about latitude 84° N. This shelf, or drowned plain, evidently marks an old extension of the continents, and its northern edge must be considered as the real margin of their masses, the coasts of which have probably been overflowed by the sea at some comparatively recent geological period. On this submarine plateau the Arctic lands are situated -Spitsbergen (with Seven Islands to the north, Bear Island and Hope Island to the south), Franz Josef Land, Novaya Zemlya, Lonely Island, the New Siberia Islands, Wrangel Island, the American Arctic archipelago. The depth of the shelf is, especially north of Siberia, very uniform, and usually not more than 50 to 80 fathoms. North of Europe it is intersected by a submarine fjord-like depression, or broad channel, extending eastward from the Norwegian Sea. Between Norway and Bear Island this depression is about 240 fathoms deep, and between Novaya Zemlya and Franz Josef Land 100 to 150 fathoms deep. It gives off several submerged fjords or channels towards the south-east into the shallow Murman Sea, e.g. one channel, more than 100 fathoms deep, along the Murman coast towards the entrance of the White Sea; another narrow channel, in parts 100 fathoms deep, along the south-west coast of Novaya Zemlya through Kara Strait. It also extends into the Kara Sea, rounding the north point of Novaya Zemlya and forming a narrow channel along its eastern coast. On the American side similar but much narrower submarine depressions, which may be called submarine fjords, extend from Baffin Bay into the continental shelf, northward through Smith Sound, Kane Basin and Kennedy Channel, and westward through Lancaster Sound. The greatest depths in the Arctic Sea have been found in the North Polar Basin, where depths of 2100 fathoms, in about 81° N. and 130° E., have been measured with certainty. It is deeper than 1650 fathoms along the whole route of the Fram," from about 79° N. and 138° E. to near Spitsbergen. In 841° N. and about 75° E. the depth is 2020 fathoms,

and in 83° N. and 13° E. it is 1860 fathoms. The northern and eastern extension of this deep basin is not known. Commander Peary reports a depth of 1500 fathoms with no bottom at 5 sea miles from the Pole (about 89° 55′ N.) where he tried to obtain a scunding. It was formerly believed that still greater depths existed west of Spitsbergen, in the so-called Swedish deep, where 2600 fathoms had been sounded, but the Nathorst expedition in 1898 found no greater depths there than about 1700 fathoms. The Norwegian Sea, farther south, is 2000 fathoms deep midway between Iceland and Norway, in about 68° N. This so-called Norwegian deep is, as before stated, separated from the North Atlantic Basin by the Wyville Thomson ridge and the Faeroe-Iceland ridge. Farther north there is a low transverse ridge extending eastwards from Jan Mayen, in about 72° N., which is about 1300 fathoms deep. North of this the sea is again deeper-1985 fathoms in 75° N. From the north-west corner of Spitsbergen a submarine ridge extends in a north-westerly direction, with depths of about 430 fathoms in 81° N. and about 4° E. How far this ridge extends is unknown, but there is a probability that it reaches Greenland, and thus separates the Swedish and the Norwegian deep from the deep depression of the North Polar Basin. Baffin Bay forms, probably, a relatively deep basin of about 1000 or 1200 fathoms, which is separated from the West Atlantic Basin by the shallow submarine ridge from Greenland to Baffin Land in about 65° or 66° N.

The deposit composing the bottom of the Arctic Sea contains in its northern part, in the North Polar Basin, extremely little matter of organic origin. It is formed mainly of mineral material, sandy clay of very fine grain, to an extent which is hardly found in any other part of the ocean with similar depths. It contains only from 1 to 4% of carbonate of lime. Farther south, in the sea between Spitsbergen and Greenland, the amount of carbonate of lime gradually increases owing to the shells of foraminifera (especially biloculinae); west of Spitsbergen the proportion rises to above 20 or even 30%, while in the direction of Greenland it is considerably lower.

The circulation of the Arctic Sea may be explained firstly by the vertical and horizontal distribution of temperature and salinity (i.e. density); secondly, by the influence of the winds, especially on the ice-covered surface. The currents in this sea may to some extent be considered as convection currents, caused by the cooling of the water near the surface, which becomes heavier, sinks, and must be replaced on the surface by warmer water coming from the south, which is also influenced by the prevailing winds. On account of the rotation of the earth the northward-running water on the surface, as well as the sinking water, will be driven in a north-easterly or easterly direction, while the southward-flowing water along the bottom, as well as the rising water, is driven south-west or westward. This very simple circulation, however, is to a great extent complicated on the one hand by the irregular configuration of the sea-bottom, especially the transverse submarine ridges-e.g. the Spitsbergen ridge, the Jan Mayen ridge, and the ScotlandFaeroe-Iceland ridge; and on the other hand by the circumstance that the upper water strata of the sea are comparatively light in spite of their low temperature. These strata, about 100 or 120 fathoms thick, are diluted by the addition of fresh water from the North European, Siberian, Canadian and Alaskan rivers, as well as by precipitation, while at the same time the evaporation from the surface of the mostly ice-covered sea is insignificant. The light surface strata will have a tendency to spread over the heavier water farther south, and thus the polar surface currents running southward along the east coasts of Greenland, Baffin Land and Labrador are formed, owing their westerly course to the rotation of the earth. These currents are certainly to a great extent helped and increased by the prevailing winds of the region. The winds get a firm hold on the rough surface of the floating ice, which, with its deep hummocks and ridges, gets a good grip of the water, transferring the movement of the surface immediately down to at least 5 or > fathoms.

The chief currents running into the Arctic Sea are the following:1. The Gulf Stream, or Atlantic drift, passing north-eastward over the Scotland-Faeroe-Iceland ridge, along the west coast of Norway, with one arm branching off eastward round the North Cape into the Barents Sea, and another branch running northward along the margin of the shelf between Norway, Bear Island and Spitsbergen, passing as a very narrow current along the west coast of the latter, over the Spitsbergen ridge (at its north-west corner), and into the North Polar Basin, where it flows gradually northward and eastward (on account of the rotation of the earth) below the cold but lighter layer, 100 fathoms thick, of polar water, and fills the whole basin below 100 or 120 fathoms to the bottom with Atlantic water.

2. The Irminger Current, running north along the west coast of Iceland. One part branches off westward and southward again in Denmark Strait, following the Greenland Polar Current, whilst another smaller part runs northward, eastward and south-eastward to the north and east of Iceland.

3. An Atlantic current runs northward along the west coast of Greenland, passes the ridge across Davis Strait, and flows into Baffin Bay, forming its deeper strata below the polar water in is a possibility that some slight portion of this current even reaches a similar way to the Gulf Stream in the North Polar Basin. There the latter along the bottom of the deep channel through Smith Sound.

4. A small current running northward into the North Polar Basin through Bering Strait.

The Arctic Sea receives also a contribution of fresh water from the rivers of northern Europe, Siberia and America, as well as from the glaciers of Greenland and the precipitation over the whole area of the sea itself.

The chief currents running out of the Arctic Sea are: (1) The Greenland Polar Current, running southward along the east coast of Greenland, and dividing into two branches north of Iceland(a) the east Greenland branch, passing south through Denmark Strait and rounding Cape Farewell; (b) the east Iceland branch, running south-eastward between Iceland and Jan Mayen, towards the Faeroes. It seems as if only a small portion of this current actually passes the Faero-Iceland ridge and reaches the Atlantic Ocean. The greater part is partly mixed with the water of the Gulf Stream and is turned by the latter in a north-easterly direction, forniing a kind of eddy or vortex movement in the southern Norwegian Sea. (2) The Labrador Polar Current, formed by the water running south through Smith Sound, Lancaster Sound and Jones Sound, as well as water from Baffin Bay, and also from the east Greenland current rounding Cape Farewell and crossing polar current also passes in a south-westerly or westerly direction Davis Strait. (3) Along the south-east coast of Spitsbergen a past South Cape, where it meets the Gulf Stream. (4) A small current probably also runs out along the western side of Bering

Strait.

Temperature and Salinity.-While the temperature is comparatively uniform, with small variations, the difference in salinity between the upper and lower strata is greater than in most other parts of the ocean. In the North Polar Basin the vertical distribution of temperature as well as salinity is very much the same in all places examined. Near the surface, from o down to 100 fathoms, the water is below the freezing point of fresh water-with a minimum of between 28-7° (-1.8° C.) and 28-6° (-1.9° C.) at a depth of about 30 fathoms-and is much diluted with fresh water (see above), the salinity gradually increasing downward from about 29 or 30 per mille near the surface to nearly 35 per mille in 100 fathoms. Below 100 fathoms the temperature as well as the salinity gradually increases, until they approach their maximum in about 160 or 200 fathoms, where the temperature varies between 32.5° (0.3° C.), north of the New Siberia Islands, and about 33-8° (1o C.) north of Franz Josef Land; and the salinity is about 35.1 per mille. From this depth the temperature gradually sinks downward; 32° (0° C.) is found at about 490 fathoms in the western part of the basine.g. between about 84° N. 15° E. and 851° N. 58° E., while it is found in about 400 fathoms farther east-e.g. in 814° N. and 123° E. In depths between 1400 and 1600 fathoms the temperature has a second minimum between 30.6° (−0·8° C.) and 30-4° (-0.9° C.), below which depth the temperature again rises slowly, a few tenths of a degree towards the bottom. In all depths below 200 fathoms the salinity of the water remains very much the same, about 35.1 per mille, with very slight variations. This comparatively warm and saline water evidently originates from the branch of the Gulf Stream passing north across the submarine ridge from north-west Spitsbergen. The vertical distribution of temperature and salinity is very much the same,

summer and winter, throughout the North Polar Basin, except near the surface, which in summer is covered by a layer of fresh water arising from the melting of the snow-covered surface of the floe-ice. This fresh-water layer may attain a thickness of 5 or 6 ft. between the floes. North of the Siberian coast the sea is, during summer, covered with a layer of warm water from the Siberian rivers, and the temperature of the surface may rise to several degrees above freezing-point.

In the Norwegian and Greenland Seas there are greater variations of temperature. Below a certain limit, which in the northern part (on the eastern side) is about 550 fathoms deep, and in the southern part between 300 and 400 fathoms deep, the whole basin of this sea is filled with water which has an unusually uniform salinity of about 34.92 per mille, and the temperature of which is below zero centigrade, gradually sinking downward from the above-mentioned limit, where it is 32° (0° C.); and down to 29.8° (-1.2° C.) or 29.6° (−1·3°C.) near the bottom in 1400 or 1600 fathoms. This cold underlying water of such a remarkably uniform and comparatively low salinity is formed chiefly in a small area between Jan Mayen and Spitsbergen, by the formation of ice and cooling down of the Atlantic surface water by radiation of heat during the winter. In this manner the surface water becomes heavier than the underlying water and gradually sinks to the bottom. This water seems to be distinctly different from the hitherto known water filling the deep of the North Polar Basin, as it has a lower salinity and lower temperature; the known bottom temperature of the North Polar Basin being between 30.7° (−0·7° C.) and 30·4° (−0·9° C.), and the salinity about 35.1 per mille. This fact seems to indicate that there can be no direct communication between the deep depression of the North Polar Basin and the Norwegian-Greenland Sea, which are probably separated by a submarine ridge running from the north-west corner of Spitsbergen to Greenland.

The above-mentioned layer of uniform cold water of the Norwegian-Greenland Sea is, along its eastern side, covered by the warm and saline water of the Gulf Stream flowing northward along the west coast of Norway, Bear Island and Spitsbergen, and forming the upper strata of the sea about 300 to 500 fathoms deep. The maximum temperature of this water is on the surface about 46° (8° C.) to 50° (10° C.) west of northern Norway, and about 37° (3°C.) to 39° (4° C.) west of Spitsbergen. The salinity is generally between 35.0 and 35.3 per mille.

Along the western side of this sea, towards the east coast of Greenland, the underlying cold water is covered by the less saline water of the polar current, which in the upper strata of the sea, from the surface down to about 100' fathoms, has very much the same temperature and salinity as in the upper cold and less saline strata of the North Polar Basin. Near the east coast of Greenland, a layer of comparatively warm and saline water, with a temperature of 32.7° (0.4° C.) and a salinity of 35.2 per mille, has been found (by the Ryder expedition in 1891) below the cold and lighter polar water in a depth of 70 to 90 fathoms. This warmer undercurrent is a continuation of the warm Spitsbergen current sending off a branch westward from Spitsbergen, and thus forming a great vortex movement in the SpitsbergenGreenland Sea similar to the one mentioned farther south in the Norwegian Sea.

water much diluted by the fresh water from the Siberian rivers, especially the Ob and the Yenisei. The salinity varies between 29 and 34 per mille; near the mouth of the rivers it is naturally much lower.

The vertical distribution of temperature and salinity in Baffin Bay seems to be very similar to that of the North Polar Basin, with a cold but less saline upper stratum of water-with a minimum temperature of about 28.9° (-1.7° C.)—and a warmer and more saline deeper stratum from 100 to 200 fathoms downwards, with a maximum temperature of 33.6° (0·9° C.) in about 200 fathoms, and the temperature slowly decreasing towards the bottom.

Arctic Ice. As before mentioned, at least two-thirds of the Arctic Sea is constantly covered by drifting ice. This ice is mostly formed on the surface of the sea itself by freezing, the so-called floe-ice or sea-ice. A small part is also river-ice, formed on the rivers, especially those of Siberia, and carried into the sea during the spring or summer. Another comparatively small part of the ice originates from the glaciers of the Arctic lands. These pieces of glacier-ice or icebergs are, as a rule, easily distinguished from the floe-ice by their size and structure. They occur almost exclusively in the seas round Greenland, where they originate from the glaciers descending into the sea from the inland ice of Greenland. Some small icebergs are also formed in Franz Josef Land, Spitsbergen, Novaya Zemlya, Grinnell Land, &c., but they are comparatively insignificant, and are not as a rule carried far from the coasts. Sea-ice or floe-ice is formed during the autumn, winter and spring, especially in the North Polar Basin, but also in the Kara Sea, the greater part of Barents Sea, the northernmost part of the Norwegian Sea (near Bear Island and towards Jan Mayen), Greenland Sea and Baffin Bay. The floe-ice does not, as a rule, grow thicker than 7 or 8 ft. in one year, but when it floats in the water for some years it may attain a thickness of 16 ft. or more directly by freezing. By the constant upheaval from pressure much greater thicknesses are attained in the piled-up hummocks and rubble which may be 20 to 30 ft. high above the water when floating. During the summer the floe-ice decreases again by melting partly on the surface owing to the direct radiation of heat from the sun, partly on the under side owing to the higher temperature of the water in which it floats. The first kind of melting is that which prevails in the North Polar Basin, which the second occurs in more southern latitudes. The floe-ice is constantly more or less in movement, carried by winds and currents. The changing wind, and also to a great extent the changing tidal current, causes diverging movements in the ice by breaking it into larger or smaller floes. When the floes separate, lanes and channels are formed; when they meet, ice-pressures arise, and the floes are piled up to form hummocks or ridges, and thus the uneven polar ice arises. In the North Polar Basin the floe-ice is slowly carried by the prevailing winds and the currents in an average direction from Bering Strait and the New Siberia Islands, north of Franz Josef Land and Spitsbergen, near the North Pole, towards the Greenland Sea and southward along the east coast of Greenland. Such a drift of an ice-floe from the sea north of Bering Strait to the east coast of Greenland probably takes, as a rule, four or five years, and the floes found in this part of the sea are not, therefore, generally older. What the drift of the ice is on the American side of the North Polar Basin is still little known. But there it is probably more or less blocked up in its southward movement by the islands of the American Arctic archipelago, and the ice-floes may thus grow very old and thick. Commander Peary found a strong easterly movement of the floes in the region north of Grant Land in 1907. The southward distribution of the drifting floe-ice (the pack ice) in Barents Sea, Norwegian-Greenland Sea and Davis Strait may differ much from one year to another, and these variations are evidently due to more or less periodical variations in the currents and also in the directions of the pre

distribution during the late winter and spring, while the late summer and autumn (end of August and September) is the most