TERRIGENOUS DE-POSITS (formed in deep or shallow See also:

• WATER

It is a remarkable See also:

• GEOGRAPHICAL

Viewed as a whole this deposit may be taken as a partial precipitation of the See also:

• PLANKTON

It has been found sporadically near the Aleutian Islands, between the Philippines and Marianne Islands and to the south of the Galapagos See also:

• GROUP

The whole collection of 231 specimens of deep-sea deposits brought back by the " Challenger " shows the following See also:

• GENERAL
• GENERAL (Lat. generalis, of or relating to a genus, kind or class)

(5,800,000 sq. m.) of the Indian Ocean and 14,000,000 sq. km. (5,400,000 sq. m.) of the Atlantic are occupied by this deposit; it is indeed the dominant submarine deposit of the water-hemisphere just as globigerina ooze is the dominant submarine deposit of the land-hemisphere. Radiolarian ooze was recognized as a distinct deposit and named by Sir John Murray on the " Challenger” expedition, but it may be viewed as red clay with an exceptionally large proportion of siliceous organic remains, especially those of the radiolarians which form part of the pelagic plankton. It does not occur in the Atlantic Ocean at all, and in the Indian Ocean it is only known See also:

• ROUND (O. Fr. rond, Lat. rotundus, the Fr. is the source also of Du. rond; Ger., Swed., Dan. and Nor. rond)

. . 55,700,000 21,500,000 15.4 1. Globigerina ooze 105,600,000 40,800,000 (29.2) 2. Pteropod ooze 1,400,000 500,000 (0.4) 3. Diatom ooze 23,200,000 8,900,000 (6.4) 4. Red clay 130,300,000 50,300,000 (36.1) 5. Radiolarian ooze . 12,200,000 4,700,000 (3'4) Geologists are agreed that littoral and hemipelagic deposits similar to those now forming are to be found in all See also:

• GEOLOGICAL

Salts of Sea-water.—Sea-water differs from fresh water by its See also:

• SALT (a common Teutonic word, cf. Dutch zout, Ger. Salz, Scand. salt; cognate with Gr. &Xs, Lat. sal)
• SALT, SIR TITUS, BART

The most numerous analyses have been carried out by See also:

• FORCHHAMMER, JOHANN GEORG (1794—1865)
• FORCHHAMMER, PETER WILHELM (18o1—1894)

. Gypsum, calcium sul- 1.26o 3.600 2,239 See also:

• PHATE

One can look on sea-water as a mixture of very dilute solutions of particular salts, each one of which after the lapse of sufficient time fills the whole space as if the other constituents did not exist, and this interdiffusion accounts easily for the uniformity of composition in the sea-water throughout the whole ocean, the only appreciable difference from point to point being the salinity or degree of concentration of the mixed solutions. The origin of the salt of the sea is attributed by some modern authorities entirely to the washing out of salts from the land by See also:

• RAIN (O.E. regn; the word is common to Teutonic languages, cf. Ger. Regen, Swed. and Dan. regn; it has been connected with Lat. rigare, to wet, Gr. 13pixeav)

8o 13 7 Sea water . . . . 0.2 10 89 The salts of salt lakes which have been formed in the areas of See also:

• INTERNAL

According to Knudsen the salinity is given in weight per thousand parts by the expression S=o•o3o-}-r•8o5o Cl where S is the salinity and Cl the amount of total halogen in a See also:

• SAMPLE (through the O. Fr. essemple, from Lat. exemplum; a doublet of " example ")

Buchanan on the "Challenger " it haq been usual for See also:

• BRITISH

Salinity per mile . . o ro 20 30 35 40 Temperature 8° C . 3.95° 1'86° — 0'31° — 2'47° — 3 52° — 4'54° Density Q8 , . . o'oo° 8'18° 16'07° 24'15° 28'22° 32'32 Further Physical Properties of Sea-water.—The See also:

• LAWS

Salinity per mille . 10 20 30 35 40 Freezing-point (C.) -0.53 -1.07 -1.63 -1.91 -2.20 Osmotic pressure Po 6.4 13.0 19.7 23• I 26.6 atmospheres . Elevation of boiling- 0.16 0.31 0.47 0.56 0.64 point (C.) . . . Reduction of vapour 4.2 8.5 13•o 15.2 17.6 pressure (mm.) . . The importance of the osmotic pressure of sea-water in See also:

• BIOLOGY (Gr. Qios, life)

From isolated observations of J. Soret and E. See also:

• SARASIN, or SARRAZIN, JEAN FRANCOIS (1611?-1654)

In the North Sea north of the Dogger See also:

• BANK

The See also:

• CHIEF (from Fr. chef, head, Lat. caput)

Observations with the xanthometer have not hitherto been numerous, but it appears that the purest blue (o-r on Forel's scale) is found in the Sargasso Sea, in the North Atlantic and in similarly situated tropical or subtropical regions in the Indian and Pacific Oceans. The northern seas have an increasing tendency towards green, the Irminger Sea showing 5-9 Forel, while in the North Sea the water is usually a pure green (10-14 Forel), the western Mediterranean shows 5-9 Forel, but the eastern is as blue as the open ocean (0-2 Forel). A pure blue colour has been observed in the cold See also:

• SOUTHERN

According to Thoulet and Chevallier the specific heat diminishes as salinity increases, so that for io per mille salinity it is o•968, for 35 per mille it is only o•932, that of pure water being taken as unity. The thermal conductivity also diminishes as salinity increases, the conductivity for heat of sea-water of 35 per mille salinity being 4.2% less than that of pure water. This means that sea-water heats and cools somewhat more readily than pure water. The surface tension, on the other hand, is greater than that of pure water and increases with the salinity, according to Krtimmel, in the manner shown by the See also:

• EQUATION (from Lat. aequatio, aequare, to equalize)

The value usually adopted is K=450X lo -7. The compressibility is in itself very small, but so great in its effect on the density of deep water in situ that the specific gravity (0°°/4°) at 2000 fathoms increases by 0.017 and at 3000 fathoms by o•o26. In other words, water which has a specific gravity of I•o28o at the surface would at the same temperature have a specific gravity of I•o45o at 2000 and 1.0540 at 3000 fathoms. If the whole mass of water in the ocean were relieved from pressure its volume would expand from 319 million cub. m. to 321.7 million cub. m., which for a surface of 139.5 million sq. m. means an increased depth of too ft. The rate of See also:

• PROPAGATION

As See also:

• GAY, JOHN (1685-1732)
• GAY, MARIE FRANCOISE SOPHIE (1776-1852)
• GAY, WALTER (1856– )

T. See also:

• FOX
• FOX, C
• FOX, CHARLES JAMES (1749-1806)
• FOX, EDWARD (c. 1496-1538)
• FOX, GEORGE (1624-1691)
• FOX, RICHARD (c. 1448-1528)
• FOX, ROBERT WERE (1789—1877)
• FOX, SIR STEPHEN (1627–1716)
• FOX, SIR WILLIAM (1812-1893)

Dittmar's analysis of the " Challenger " samples indicated an excess of oxygen in the surface water of high southern latitudes and a deficiency at depths below 50 fathoms. The facts regarding carbonic acid in sea-water are even less understood, for here we have to do not only with the solution of the gas but also with a chemical See also:

• COMBINATION (Lat. combinare, to combine)

The amount of carbonic acid in solution may also be increased by submarine exhalations in regions of volcanic disturbance, but it must be remembered that the See also:

• CRITICAL (in alphabetical order of authors)

Buchanan on the " Challenger " were vitiated by the incompleteness of the method employed, but they are none the less of value in showing clearly that the waters of the far south of the Indian Ocean are relatively rich in carbonic acid and the tropical areas deficient. Distribution of Salinity.—A great See also:

• DEAL

The average salinity of the whole surface of the oceans may be taken as 34.5 per mille. The See also:

• VERTICAL (from Lat. vertex, highest point)

L. Ekman made further improvements; and, finally, O. Pettersson and F. Nansen perfected the instrument, adapting it not only for enclosing a portion of water at any desired depth, but by a series of concentric divisions insulating in the central compartment water at the temperature it had at the moment of collection. By means of a weight dropped along the line the water-bottle can be shut and a sample enclosed at any desired depth. The use of a sliding weight is not recommended in depths much exceeding zoo fathoms on account of the time required and the See also:

• RISK

The observations made on the " Challenger " and " Gazelle," though enabling some perfectly sound general conclusions to be See also:

• DRAWN

Temperature of the Oceans.—There is no difficulty in observing the temperature of the surface of the sea on board ship, the' only precautions required being to draw the water in a bucket which has not been heated in the sun in summer or exposed to See also:

• FROST (a common Teutonic word, cf. Dutch, vorst, Ger. Frost, from the common Teutonic verb meaning " to freeze," Dutch, vriezcn, Ger. frieren; the Indo-European root is seen in Lat. pruina, hoar-frost, cf. prurire, to itch, burn, pruna, burning coal, Sans
• FROST, WILLIAM EDWARD (1810–1877)

These See also:

• INSTRUMENTS

All thermometers sunk into deep water must be protected against the enormous pressure to which they are exposed. This may be done by the method suggested by See also:

• ARAGO, DOMINIQUE FRANCOIS JEAN (1786-1853)

Luksch deduced a much greater penetration of solar warmth from the comparison of observations at different See also:

• HOURS, CANONICAL

The figures quoted above are differences between the average surface temperatures of the warmest and of the coldest See also:

• MONTH
• MONTH (a common Teutonic word, cf. Ger. Mond, Du. maand, Dan. maaned, &c., and cognate with Lat. mensis, Gr. µi7v, &c., in other branches of the Indo-Germanic family; all ultimately from the root seen in the word for the moon in nearly all those languages

Over 770 F. (25° C) . . 22.4 38.o 40'1 Over 68° F. (20° C) . . . 50.1 51.7 58.4 This disparity results in some degree at least from the See also:

• COMPARATIVE

The great difference in salinity between the surface and the deep water excludes the possibility of effective convection in the seas of northern Europe, and in the open ocean the currents which are felt everywhere, and especially those with a vertical component, must exercise a very disturbing influence on convection. The vertical distribution of temperature in the open ocean is much better known than that of salinity. The regional differences of temperatureat like depths become less as the depth increases. Thus at 300 fathoms greater differences than 90 F. hardly ever occur between 500 N. and 5o° S., in 800 fathoms the differences are less than 5.50 and in 1500 fathoms less than 20. Even in the tropics the high temperature of the surface is confined to a very shallow layer; thus in the Central Pacific where the surface temperature is 82° F. the temperature at loc. fathoms is only 5z° F. The whole ocean must thus form but a cold dwelling-place for the organisms of the deep sea. Sir John Murray calculates that at least 8o% of the water in the ocean has a temperature always less than 400 F., and a recent calculation by Krummel gave in fact a mean temperature of 390 F. for the whole ocean. The normal vertical distribution of temperature is illustrated in See also:

• CURVE (Lat. curvus, bent)

In autumn the enclosed seas of high latitudes frequently present a thermal stratification in which a warm middle layer is sandwiched between a cold upper layer and a cold mass below, the arrangement being termed mesothermic (µSee also:

• EROS

39.6° F., not even at the bottom of the great See also:

• BARTLETT, JOHN (1820-1905)
• BARTLETT, JOHN RUSSELL (18o5-1886)
• BARTLETT, PAUL WAYLAND (18654 )

5.40 F. above the temperature at the same depth off the Azores. In shallow seas such as the North Sea and the British fringing seas, where tidal currents run strong, there is a general mixing together of the surface and deeper water, thus making the arrangement of vertical temperature anathermic in summer and katathermic in winter, while at the transitional periods in See also:

• SPRING (from " to spring," " to leap or jump up," " burst out," O. Eng., springau, a common Teut. word, cf. Ger. springer, possibly allied to Gr. QnrFpxecOac, to move rapidly)

Pettersson, J. Hjort and Helland-Hansen in the Scandinavian fjords. Sea Ice.—The freezing-point of sea-water is lower as the salinity increases and normal sea-water of 35 per mille salinity freezes at 28.6° F. Experience shows that sea-water can be cooled considerably below the freezing-point without freezing if there is no ice or See also:

• SNOW (in O. Eng. sndw; a common Indo-European word; cf. in Teutonic languages, Ger. Schnee, Du. sneeuw; in Slavonic snieg', Lith. snegas; Gr. vi4a, Lat. nix, nivis, whence the Romanic forms, Ital. neve, Fr. neige, &c.; Ir. and Gael. sneachd; the original

Such formations, termed toross by the Russians, may extend under water, according to Makaroff's investigations, to at least an equal depth. Such old sea-ice when prevented from escaping forms the palaeocrystic sea of See also:

• NARES, SIR GEORGE STRONG (1831– )

The Greenland icebergs are carried by the Labrador current across the great See also:

• BANKS, GEORGE LINNAEUS (1821-1881)
• BANKS, NATHANIEL PRENTISS (1816–1894)
• BANKS, SIR JOSEPH
• BANKS, THOMAS (1735-1805)

The general lines of the currents of the oceans are fairly well understood, and along the most frequented ocean routes the larger seasonal variations have also been ascertained. The general See also:

• SCHEME (Lat. schema, Gr. oxfjya, figure, form, from the root axe, seen in exeiv, to have, hold, to be of such shape, form, &c.)

Modern investigations have shown, however, that the relationship is by no means so simple as appears at first. We must remember that the ocean is a continuous See also:

• SHEET

A strong wind of 38 m. an hour would produce a drift-current depth of 82 fathoms in latitude 45°, and a light See also:

• BREEZE

If we assign to a See also:

• COLUMN (Lat. columna)

Differences of density between the waters of enclosed seas and of the ocean are brought about in some instances by concentration of the water of the sea on account of active evaporation, and in other instances by dilution on account of the great influx of land water. A very powerful vertical circulation is thus set up between enclosed seas and the outer ocean. The very dense water of the Red Sea and the Mediterranean makes the column of water See also:

• SALTER, JOHN WILLIAM (1820-1869)

The determination of the exact relationship of cause and effect in the origin of ocean currents is a matter of great practical importance. The researches of Pettersson, Meinardus, H. N. Dickson and others leave no doubt, for example, that the variations in the intensity of the Gulf Stream, whether these be measured by the change in the strength of the current or in the heat stored in the water, produce great variations in the character of the weather of northern Europe. The connexion between variations of current strength and the conditions of existence and distribution of plankton are no less important, especially as they act directly or indirectly on the life-conditions of See also:

• FOOD
• FOOD (like the verb " to feed," from a Teutonic root, whence O. Eng. foda; cf. " fodder "; connected with Gr. lrareicOae, to feed)

Krummel, Handbuch der Ozeano-graphie (2 vols., See also:

• STUTTGART

See also:

• ROY, WILLIAM (1726-1790)

See also:

• SURVEYING

Makaroff, Le Vitiaz et l'Ocean Pacifique, 2886-1889 (St See also:

• PETERSBURG

Soc., London) ; Bulletin des resultats acquis See also:

• PENDANT (through Fr. from Lat. pendere, to hang)